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Tolman's adaptation

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  • michawalth3
    Hi Bob & Lin plus Group, I would say that there isn t much of an adaptation, a pic of the bottom looks like its from the Atkin plans. The only difference I see
    Message 1 of 16 , Apr 6, 2008
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      Hi Bob & Lin plus Group, I would say that there isn't much of an
      adaptation, a pic of the bottom looks like its from the Atkin plans.
      The only difference I see is the box keel's stern post is steeply
      angled making the flat bottom shorter than the Atkin design. I thought
      when Tolman spoke of adaptation he meant deep-V not flat bottom and
      was disappointed, I had hoped to see how he would handle that. Somehow
      I think & feel deep in my sore bones that it's possible but can't
      quite figure it out myself.
      I'm also thinking that since Mr. Atkin spent some 30 yrs refining the
      design I will use his plans for first boat, second boat I'll
      experiment with V bottom ideas. Such are my thoughts, ideas and
      opinion. Thanks, Mike
    • Kenneth Grome
      Hi Mike, ... While I agree that he probably didn t make any major visible changes, he did make one or more changes that could be significant in terms of
      Message 2 of 16 , Apr 6, 2008
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        Hi Mike,


        > I would say that there isn't much of an adaptation,
        > a pic of the bottom looks like its from the Atkin plans.

        While I agree that he probably didn't make any major visible changes, he
        did make one or more changes that could be significant in terms of
        performance.


        > The only difference I see is the box keel's stern post is
        > steeply angled making the flat bottom shorter than
        > the Atkin design.

        My box keel's stern post is absolutely vertical. I'm not sure where you
        are seeing this non-vertical stern post in a Tolman Seabright skiff,
        but I don't think this is a significant difference anyways. Here's
        what I think may be significant:

        Renn deepened (made higher) the tunnel-stern pocket on his boat by more
        than 10 percent because he wanted people to be able to use a bigger
        propeller than the one specified by William Atkin. A deeper tunnel
        pocket has the following effects:

        1- It forces the boat to lift more water in order to keep the tunnel
        pocket filled. This requires more horsepower to do the extra lifting,
        which means less HP is available to push the boat forward, and
        therefore the result is lower fuel efficiency and higher fuel costs.

        2- It makes the water's path less streamlined as it flows into and out
        of the more deeply curved tunnel pocket. This has the effect of
        reducing the boat's top speed, forcing the bow down even further, and
        possibly making the boat handle unpredictably at speed.

        The original Rescue Minors built decades ago had the reported bad habit
        of digging their bows into the water too deeply when at speed. This
        made them handle unsafely at these speeds. To fix this Atkin recommend
        installing "lifting strakes" forward. These strakes counteracted the
        tendency of the hull to bury its bow too deeply, and this made a better
        boat with safer and more predictable handling. For this reason I wish
        Renn had started with his Widebody hull (instead of the Standard)
        because the Widebody already has lifting strakes built into the hull
        whereas the Standard does not.

        Sincerely,
        Ken Grome
        Bagacay Boatworks
        www.bagacayboatworks.com
      • Kenneth Grome
        ... I don t think it is possible to get Seabright tunnel-stern performance and efficiency out of a modification that radically changes the bottom into a
        Message 3 of 16 , Apr 6, 2008
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          > I thought when Tolman spoke of adaptation he meant
          > deep-V not flat bottom and was disappointed, I had
          > hoped to see how he would handle that. Somehow I
          > think & feel deep in my sore bones that it's possible
          > but can't quite figure it out myself.

          I don't think it is possible to get Seabright tunnel-stern performance
          and efficiency out of a modification that radically changes the bottom
          into a completely different boat.

          I have experimented with these designs for hundreds of hours, and
          although I have a design that employs a vee-bottom "wedge keel" where
          Atkin uses a flat-bottom boox keel, I'm sure it will be nowhere near as
          fuel efficient as his flat bottom designs. On the other hand I do
          believe it would be a better boat for slogging along at moderate speeds
          in heavy seas -- with the added cost of greater fuel consumption of
          course.

          In my opinion there is really nothing wrong with a flat bottom in these
          Seabright tunnel-stern boat anyways. Theys are designed to keep their
          bows in the water so they cannot 'pound' when they come down on top of
          a wave -- because they slice through them rather than banging down on
          top of them.

          Apparently what so many people fear in a flat bottom boat is the
          pounding ... but by removing the possibility of pounding I think you
          have a very good reason for a flat bottom boat like this ... :)


          > I'm also thinking that since Mr. Atkin spent some
          > 30 yrs refining the design I will use his plans for
          > first boat, second boat I'll experiment with V bottom
          > ideas.

          If you really want to take advantage of William Atkin's 30+ years of
          experience in refining these tunnel-stern Seabright skiffs, it would
          seem to make sense to build the last boat he designed in this series --
          Shoals Runner.

          If I still recall my facts correctly, Shoals Runner came along more than
          500 designs AFTER Rescue Minor. That's a lot of time to learn what was
          wrong with Rescue Minor and the other early tunnel-stern designs so
          corrections could be incorporated into Shoals Runner!

          :)

          By the way, someone mentioned the other day that Shoals Runner's chines
          are 5 inches below the waterline aft whereas Rescue Minor's chines are
          virtually at the waterline. I have studied these designs and the
          related literature intensely enough now to have convinced myself that
          there is a very good reason for this improvement in Shoals Runner:

          I think Atkin learned that when the chines are at the waterline (as in
          Rescue Minor) the boat sucks air into the tunnel pocket from the sides
          when driven in a chop, and this makes the prop ventilate and lose
          efficiency. By keeping the chines well below the waterline in Shoals
          Runner he eliminated this issue ... and produced a better boat.

          Sincerely,
          Ken Grome
          Bagacay Boatworks
          www.bagacayboatworks.com
        • Bob & Lin
          I will be curious about the minimum possible speed. Especially with a larger prop. I fish now with a 34 Albin and when I put her into gear with the lowest
          Message 4 of 16 , Apr 6, 2008
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            I will be curious about the minimum possible speed.
            Especially with a larger prop.
            I fish now with a 34' Albin and when I put her into gear with the lowest
            possible RPM I am doing 4 kts.
            That is just too fast for trolling for striped bass. I had to spring for a
            trolling valve to put on the tranny to reduce the pressure so I can get down
            to a knot or 2. Another grand I can't spend on diesel fuel. (That is one
            fill up now).
            A nice slow troll is essential for the big bass.
            Bob

            On Sun, Apr 6, 2008 at 10:16 PM, Kenneth Grome <bagacayboatworks@...>
            wrote:

            > Hi Mike,
            >
            > > I would say that there isn't much of an adaptation,
            > > a pic of the bottom looks like its from the Atkin plans.
            >
            > While I agree that he probably didn't make any major visible changes, he
            > did make one or more changes that could be significant in terms of
            > performance.
            >
            > > The only difference I see is the box keel's stern post is
            > > steeply angled making the flat bottom shorter than
            > > the Atkin design.
            >
            > My box keel's stern post is absolutely vertical. I'm not sure where you
            > are seeing this non-vertical stern post in a Tolman Seabright skiff,
            > but I don't think this is a significant difference anyways. Here's
            > what I think may be significant:
            >
            > Renn deepened (made higher) the tunnel-stern pocket on his boat by more
            > than 10 percent because he wanted people to be able to use a bigger
            > propeller than the one specified by William Atkin. A deeper tunnel
            > pocket has the following effects:
            >
            > 1- It forces the boat to lift more water in order to keep the tunnel
            > pocket filled. This requires more horsepower to do the extra lifting,
            > which means less HP is available to push the boat forward, and
            > therefore the result is lower fuel efficiency and higher fuel costs.
            >
            > 2- It makes the water's path less streamlined as it flows into and out
            > of the more deeply curved tunnel pocket. This has the effect of
            > reducing the boat's top speed, forcing the bow down even further, and
            > possibly making the boat handle unpredictably at speed.
            >
            > The original Rescue Minors built decades ago had the reported bad habit
            > of digging their bows into the water too deeply when at speed. This
            > made them handle unsafely at these speeds. To fix this Atkin recommend
            > installing "lifting strakes" forward. These strakes counteracted the
            > tendency of the hull to bury its bow too deeply, and this made a better
            > boat with safer and more predictable handling. For this reason I wish
            > Renn had started with his Widebody hull (instead of the Standard)
            > because the Widebody already has lifting strakes built into the hull
            > whereas the Standard does not.
            >
            > Sincerely,
            > Ken Grome
            > Bagacay Boatworks
            > www.bagacayboatworks.com
            >
            >
            >



            --
            I'll keep looking for the haystack, 'cause when I look in Linda's eyes
            The thought there is a needle, makes it worth a thousand tries...


            [Non-text portions of this message have been removed]
          • Mike Dolph
            Mike, I wouldn t think you would want to try anything with a V keel configuration. It s the flat waterplane of the wide keel that gives the semi displacement
            Message 5 of 16 , Apr 6, 2008
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              Mike,

              I wouldn't think you would want to try anything with a V keel
              configuration. It's the flat waterplane of the wide keel that gives
              the semi displacement performance of the design. Just looking at the
              body sections will convince you it's not the forward sections deep V
              between the first and second chines that's supplying all that lift nor
              is the reverse between the second and third chines aft, though there
              is a suggestion of dynamic lift there with the action of the
              propeller. It's plain that when running level, as it does there's not
              much in the water back there to compare with what you would see in a V
              bottom semiplaning or planing type hull.

              She runs on her middle not on her tail. I haven't seen a plan of
              Tolman's adaptation so I'm talking about Rescue Minor of course.

              Mike Dolph

              --- In AtkinBoats@yahoogroups.com, "michawalth3" <michawalth3@...> wrote:
              >
              > Hi Bob & Lin plus Group, I would say that there isn't much of an
              > adaptation, a pic of the bottom looks like its from the Atkin plans.
              > The only difference I see is the box keel's stern post is steeply
              > angled making the flat bottom shorter than the Atkin design. I thought
              > when Tolman spoke of adaptation he meant deep-V not flat bottom and
              > was disappointed, I had hoped to see how he would handle that. Somehow
              > I think & feel deep in my sore bones that it's possible but can't
              > quite figure it out myself.
              > I'm also thinking that since Mr. Atkin spent some 30 yrs refining the
              > design I will use his plans for first boat, second boat I'll
              > experiment with V bottom ideas. Such are my thoughts, ideas and
              > opinion. Thanks, Mike
              >
            • Michael Walther
              Hi Ken & Group, Thanks for the response. The drawing does show a much taller tunnel and your correct about its effects and looking at them again I have to say
              Message 6 of 16 , Apr 6, 2008
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                Hi Ken & Group, Thanks for the response. The drawing does show a much taller tunnel and your correct about its effects and looking at them again I have to say I don't know why my brain saw such a steep angle of the stern post, but sometimes it does that and it is more angled than Rescue Minors. As for what difference it would make I don't know for sure but I believe it's detrimental. The pic I refer to is Renn's boat not yours. Unless Tolman's site site features your boat & not his. The Renn Tolman link at bottom of page, link #3 Tolman Seabright at bottom of link page.
                Robb White did mention that in his article in WB and I think your right about Renn's choice of hulls. Thanks, Mike

                --- On Mon, 4/7/08, Kenneth Grome <bagacayboatworks@...> wrote:

                > From: Kenneth Grome <bagacayboatworks@...>
                > Subject: Re: [AtkinBoats] Tolman's adaptation
                > To: AtkinBoats@yahoogroups.com
                > Date: Monday, April 7, 2008, 2:16 AM
                > Hi Mike,
                >
                >
                > > I would say that there isn't much of an
                > adaptation,
                > > a pic of the bottom looks like its from the Atkin
                > plans.
                >
                > While I agree that he probably didn't make any major
                > visible changes, he
                > did make one or more changes that could be significant in
                > terms of
                > performance.
                >
                >
                > > The only difference I see is the box keel's stern
                > post is
                > > steeply angled making the flat bottom shorter than
                > > the Atkin design.
                >
                > My box keel's stern post is absolutely vertical.
                > I'm not sure where you
                > are seeing this non-vertical stern post in a Tolman
                > Seabright skiff,
                > but I don't think this is a significant difference
                > anyways. Here's
                > what I think may be significant:
                >
                > Renn deepened (made higher) the tunnel-stern pocket on his
                > boat by more
                > than 10 percent because he wanted people to be able to use
                > a bigger
                > propeller than the one specified by William Atkin. A
                > deeper tunnel
                > pocket has the following effects:
                >
                > 1- It forces the boat to lift more water in order to keep
                > the tunnel
                > pocket filled. This requires more horsepower to do the
                > extra lifting,
                > which means less HP is available to push the boat forward,
                > and
                > therefore the result is lower fuel efficiency and higher
                > fuel costs.
                >
                > 2- It makes the water's path less streamlined as it
                > flows into and out
                > of the more deeply curved tunnel pocket. This has the
                > effect of
                > reducing the boat's top speed, forcing the bow down
                > even further, and
                > possibly making the boat handle unpredictably at speed.
                >
                > The original Rescue Minors built decades ago had the
                > reported bad habit
                > of digging their bows into the water too deeply when at
                > speed. This
                > made them handle unsafely at these speeds. To fix this
                > Atkin recommend
                > installing "lifting strakes" forward. These
                > strakes counteracted the
                > tendency of the hull to bury its bow too deeply, and this
                > made a better
                > boat with safer and more predictable handling. For this
                > reason I wish
                > Renn had started with his Widebody hull (instead of the
                > Standard)
                > because the Widebody already has lifting strakes built into
                > the hull
                > whereas the Standard does not.
                >
                > Sincerely,
                > Ken Grome
                > Bagacay Boatworks
                > www.bagacayboatworks.com
                >
                >
                >
                >
                >
                >
                >
                > ------------------------------------
                >
                > No flaming, cursing, politics, religion or public mopery.
                > Please be polite.
                >
                > If you set out to build an Atkin boat, please do not modify
                > the plans. If you stray from the plans you do so at your own
                > risk and Atkin & Co. will take no responsibility for the
                > performance of the resulting boat.
                >
                > The current Atkin boat plans catalog is online at
                > <http://www.atkinboatplans.com/>
                >
                > Yahoo! Groups Links
                >
                >
                >

                ____________________________________________________________________________________
                You rock. That's why Blockbuster's offering you one month of Blockbuster Total Access, No Cost.
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              • Kenneth Grome
                Hi Mike, ... I hadn t seen that drawing you ve been referring to until a few minutes ago. It looks similar to the plans I worked from. I know Renn changed
                Message 7 of 16 , Apr 7, 2008
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                  Hi Mike,


                  > The drawing does show a much taller tunnel and
                  > your correct about its effects and looking at them
                  > again I have to say I don't know why my brain saw
                  > such a steep angle of the stern post, but sometimes
                  > it does that and it is more angled than Rescue Minors.

                  I hadn't seen that drawing you've been referring to until a few minutes
                  ago. It looks similar to the plans I worked from. I know Renn changed
                  some things after I started building my hull, but I'm not sure which
                  things were changed. Probably not many, and probably nothing major
                  since my building of this hull was done specifically to prove the
                  validity of the plans he sent me.


                  > As for what difference it would make I don't know
                  > for sure but I believe it's detrimental.

                  I wouldn't call it detrimental. Shortening the flat box keel bottom and
                  using an angled stern post will reduce the flat planing surface, but
                  the difference is so small that I don't think anyone would ever notice
                  it. Basically I think the vertical or angled stern post is a
                  non-issue.


                  > The pic I refer to is Renn's boat not yours. Unless
                  > Tolman's site site features your boat & not his.

                  Renn doesn't have any of my pictures on his site, and none of my
                  pictures are on the fishyfish.com site either. All my pictures are
                  here, and they are all photographs, not drawings or sketches:

                  http://www.bagacayboatworks.com/images/seabright01/
                  http://www.bagacayboatworks.com/images/seabright02/
                  http://www.bagacayboatworks.com/images/seabright03/

                  Sincerely,
                  Ken Grome
                  Bagacay Boatworks
                  www.bagacayboatworks.com
                • Alan Boman
                  Ken, ... William was 61 when he designed River Belle in 1943 - does anyone know how many other Tunnel Stern designs came after that period or where the
                  Message 8 of 16 , Apr 7, 2008
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                    Ken,

                    >If I still recall my facts correctly, Shoals Runner came along more than
                    >500 designs AFTER Rescue Minor. That's a lot of time to learn what was
                    >wrong with Rescue Minor and the other early tunnel-stern designs so
                    >corrections could be incorporated into Shoals Runner!

                    William was 61 when he designed "River Belle" in 1943 - does anyone know how
                    many other Tunnel Stern designs came after that period or where the
                    chronology of his designs can be found ? Not that I have a vested interest
                    of course....

                    Alan





                    [Non-text portions of this message have been removed]
                  • Michael Walther
                    Hi Ken & Group again, Thanks for responding. Actually I was responding to Bob & Lin s general request for thoughts & opinions of Tolman s adaptation. What I
                    Message 9 of 16 , Apr 7, 2008
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                      Hi Ken & Group again, Thanks for responding. Actually I was responding to Bob & Lin's general request for thoughts & opinions of Tolman's adaptation. What I had hoped to see was blending of the two types. "Somehow I think & feel deep in my sore bones that it's possible but can't quite figure it out myself." I still believe it's possible. After having sent my responses & just before taking a nap, I think I may have worked it out. The changes I'm referring to are not as radical as you are imagining. My thoughts on the matter are a miner change in the bow of the box keel (between forward half & third only). I am fully aware of the lines of this design, I have an enlarged copy open on my screen at all times, for studying between other what to be dons, while working out my thoughts on what's possible with it. You're right, the changes you've mentioned would get those awful results. I've looked at Shoals Runner again, it goes farther from my needs. I live in
                      Wash., D.C., the tidewater Potomac & Cheasapeake (spelling by Capt. John Smith) are not all that shallow, as shown by square rig, tall ship USCG Eagle's 1976 visit (breath taking close up from my parents boat) or protected, with the weather patterns at this latitude along with its geography, it can get quite rough. Also I've been in all hull types, some in really bad conditions here. Rescue Minor's hull design with minimal changes I have in mind, I believe would be closest what I'm looking for. But, I will consider & study the implications of Shoals Runner's deeper chines carefully. Your thoughts, ideas and experience have been helpful & confirmed mine. I read & enjoy all your input from the other groups as well. I almost always learn something. Thanks, Mike

                      --- On Mon, 4/7/08, Kenneth Grome <bagacayboatworks@...> wrote:

                      > From: Kenneth Grome <bagacayboatworks@...>
                      > Subject: [AtkinBoats] More thoughts on tunnel-stern Seabright skiffs ...
                      > To: AtkinBoats@yahoogroups.com
                      > Date: Monday, April 7, 2008, 2:19 AM
                      > > I thought when Tolman spoke of adaptation he meant
                      > > deep-V not flat bottom and was disappointed, I had
                      > > hoped to see how he would handle that. Somehow I
                      > > think & feel deep in my sore bones that it's
                      > possible
                      > > but can't quite figure it out myself.
                      >
                      > I don't think it is possible to get Seabright
                      > tunnel-stern performance
                      > and efficiency out of a modification that radically changes
                      > the bottom
                      > into a completely different boat.
                      >
                      > I have experimented with these designs for hundreds of
                      > hours, and
                      > although I have a design that employs a vee-bottom
                      > "wedge keel" where
                      > Atkin uses a flat-bottom boox keel, I'm sure it will be
                      > nowhere near as
                      > fuel efficient as his flat bottom designs. On the other
                      > hand I do
                      > believe it would be a better boat for slogging along at
                      > moderate speeds
                      > in heavy seas -- with the added cost of greater fuel
                      > consumption of
                      > course.
                      >
                      > In my opinion there is really nothing wrong with a flat
                      > bottom in these
                      > Seabright tunnel-stern boat anyways. Theys are designed to
                      > keep their
                      > bows in the water so they cannot 'pound' when they
                      > come down on top of
                      > a wave -- because they slice through them rather than
                      > banging down on
                      > top of them.
                      >
                      > Apparently what so many people fear in a flat bottom boat
                      > is the
                      > pounding ... but by removing the possibility of pounding I
                      > think you
                      > have a very good reason for a flat bottom boat like this
                      > ... :)
                      >
                      >
                      > > I'm also thinking that since Mr. Atkin spent some
                      > > 30 yrs refining the design I will use his plans for
                      > > first boat, second boat I'll experiment with V
                      > bottom
                      > > ideas.
                      >
                      > If you really want to take advantage of William Atkin's
                      > 30+ years of
                      > experience in refining these tunnel-stern Seabright skiffs,
                      > it would
                      > seem to make sense to build the last boat he designed in
                      > this series --
                      > Shoals Runner.
                      >
                      > If I still recall my facts correctly, Shoals Runner came
                      > along more than
                      > 500 designs AFTER Rescue Minor. That's a lot of time
                      > to learn what was
                      > wrong with Rescue Minor and the other early tunnel-stern
                      > designs so
                      > corrections could be incorporated into Shoals Runner!
                      >
                      > :)
                      >
                      > By the way, someone mentioned the other day that Shoals
                      > Runner's chines
                      > are 5 inches below the waterline aft whereas Rescue
                      > Minor's chines are
                      > virtually at the waterline. I have studied these designs
                      > and the
                      > related literature intensely enough now to have convinced
                      > myself that
                      > there is a very good reason for this improvement in Shoals
                      > Runner:
                      >
                      > I think Atkin learned that when the chines are at the
                      > waterline (as in
                      > Rescue Minor) the boat sucks air into the tunnel pocket
                      > from the sides
                      > when driven in a chop, and this makes the prop ventilate
                      > and lose
                      > efficiency. By keeping the chines well below the waterline
                      > in Shoals
                      > Runner he eliminated this issue ... and produced a better
                      > boat.
                      >
                      > Sincerely,
                      > Ken Grome
                      > Bagacay Boatworks
                      > www.bagacayboatworks.com
                      >
                      >
                      >
                      >
                      >
                      >
                      >
                      > ------------------------------------
                      >
                      > No flaming, cursing, politics, religion or public mopery.
                      > Please be polite.
                      >
                      > If you set out to build an Atkin boat, please do not modify
                      > the plans. If you stray from the plans you do so at your own
                      > risk and Atkin & Co. will take no responsibility for the
                      > performance of the resulting boat.
                      >
                      > The current Atkin boat plans catalog is online at
                      > <http://www.atkinboatplans.com/>
                      >
                      > Yahoo! Groups Links
                      >
                      >
                      >

                      ____________________________________________________________________________________
                      You rock. That's why Blockbuster's offering you one month of Blockbuster Total Access, No Cost.
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                    • Michael Walther
                      Hi Mike and Group, Thanks for responding. The adaptation which looks the same as Rescue Minor & almost identical to, but not. The Tolman Skiff is a modified
                      Message 10 of 16 , Apr 7, 2008
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                        Hi Mike and Group, Thanks for responding. The 'adaptation' which looks the same as Rescue Minor & almost identical to, but not. The Tolman Skiff is a modified deep V generally akin to Huckins' famous WWII PT Boat design. I had hoped to see a blending of the two hull forms. And if you're not familiar with both, it's almost impossible to understand what I was trying to say. My idea would be to incorporate & blend a V into the forward half only, leaving last half flat for a softer ride in the rougher water of the Potomac & Cheasapeake (Capt. John Smith's spelling, it's a history thing:). It's the flat bottom in combination with the piroge type ending of the box keels stern post that gives it semi displacement performance. The flat of the box keel and downward angle of the tunnel above the prop to the transom is what provides the lift to actually plane & if you'll notice the drive shaft and tunnel angle are the same, which directs the force down past the
                        transom. Your statement that "She runs on her middle not on her tail." is absolutely, positively correct, I couldn't agree more. Thanks, a different Mike


                        --- On Mon, 4/7/08, Mike Dolph <johndolph@...> wrote:

                        > From: Mike Dolph <johndolph@...>
                        > Subject: [AtkinBoats] Re: Tolman's adaptation
                        > To: AtkinBoats@yahoogroups.com
                        > Date: Monday, April 7, 2008, 3:15 AM
                        > Mike,
                        >
                        > I wouldn't think you would want to try anything with a
                        > V keel
                        > configuration. It's the flat waterplane of the wide
                        > keel that gives
                        > the semi displacement performance of the design. Just
                        > looking at the
                        > body sections will convince you it's not the forward
                        > sections deep V
                        > between the first and second chines that's supplying
                        > all that lift nor
                        > is the reverse between the second and third chines aft,
                        > though there
                        > is a suggestion of dynamic lift there with the action of
                        > the
                        > propeller. It's plain that when running level, as it
                        > does there's not
                        > much in the water back there to compare with what you would
                        > see in a V
                        > bottom semiplaning or planing type hull.
                        >
                        > She runs on her middle not on her tail. I haven't seen
                        > a plan of
                        > Tolman's adaptation so I'm talking about Rescue
                        > Minor of course.
                        >
                        > Mike Dolph
                        >
                        > --- In AtkinBoats@yahoogroups.com, "michawalth3"
                        > <michawalth3@...> wrote:
                        > >
                        > > Hi Bob & Lin plus Group, I would say that there
                        > isn't much of an
                        > > adaptation, a pic of the bottom looks like its from
                        > the Atkin plans.
                        > > The only difference I see is the box keel's stern
                        > post is steeply
                        > > angled making the flat bottom shorter than the Atkin
                        > design. I thought
                        > > when Tolman spoke of adaptation he meant deep-V not
                        > flat bottom and
                        > > was disappointed, I had hoped to see how he would
                        > handle that. Somehow
                        > > I think & feel deep in my sore bones that it's
                        > possible but can't
                        > > quite figure it out myself.
                        > > I'm also thinking that since Mr. Atkin spent some
                        > 30 yrs refining the
                        > > design I will use his plans for first boat, second
                        > boat I'll
                        > > experiment with V bottom ideas. Such are my thoughts,
                        > ideas and
                        > > opinion. Thanks, Mike
                        > >
                        >
                        >
                        >
                        > ------------------------------------
                        >
                        > No flaming, cursing, politics, religion or public mopery.
                        > Please be polite.
                        >
                        > If you set out to build an Atkin boat, please do not modify
                        > the plans. If you stray from the plans you do so at your own
                        > risk and Atkin & Co. will take no responsibility for the
                        > performance of the resulting boat.
                        >
                        > The current Atkin boat plans catalog is online at
                        > <http://www.atkinboatplans.com/>
                        >
                        > Yahoo! Groups Links
                        >
                        >
                        >

                        ____________________________________________________________________________________
                        You rock. That's why Blockbuster's offering you one month of Blockbuster Total Access, No Cost.
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                      • Kenneth Grome
                        ... I asked about the chronology previously in this group, and someone posted the info I ve been using and relating to others. The same info is probably still
                        Message 11 of 16 , Apr 7, 2008
                        • 0 Attachment
                          > William was 61 when he designed "River Belle" in 1943 - does anyone
                          > know how many other Tunnel Stern designs came after that period or
                          > where the chronology of his designs can be found ? Not that I have a
                          > vested interest of course....


                          I asked about the chronology previously in this group, and someone
                          posted the info I've been using and relating to others. The same info
                          is probably still in the list archives.

                          Dave Gerr designed some larger boats using tunnel-sterns but apparently
                          they do not match the efficiency of the smaller Atkin designs. This
                          (and my gut instinct) tells me the advantages of the larger
                          tunnel-stern designs such as River Belle come more from their protected
                          propellers and shallow draft than their greater fuel efficiency.

                          I think multihulls are a better bet in terms of efficiency when boats
                          the length of River Belle or longer are concerned. They provide more
                          livable space too.

                          Sincerely,
                          Ken Grome
                          Bagacay Boatworks
                          www.bagacayboatworks.com
                        • Kenneth Grome
                          ... I would like to understand what you re suggesting here, and I m not sure I get it just yet ... Do you mean to design the front half of the boat more or
                          Message 12 of 16 , Apr 7, 2008
                          • 0 Attachment
                            > My idea would be to incorporate & blend a
                            > V into the forward half only, leaving last half
                            > flat for a softer ride in the rougher water of
                            > the Potomac & Cheasapeake.


                            I would like to understand what you're suggesting here, and I'm not sure
                            I 'get it' just yet ...

                            Do you mean to design the front half of the boat more or less like the
                            Tolman Seabright skiff is designed now -- but instead of twisting the
                            garboard panels so that they become an inverted vee in the aft tunnel
                            section behind the end of the box keel, these garboard panels would
                            instead twist only enough so that they will end up horizontal in the
                            athwartship direction -- possibly while retaining the downward 'hook'
                            of the bottom at the transom?

                            If this is what you mean, the aft chines will remain above the water
                            when the boat is at rest, offering no lateral stability over what the
                            pirogue-shaped box keel and the center / front portion of the hull
                            provides -- which is not much relatively speaking. The simple solution
                            here is to reduce the height of the box keel, or better yet narrow it
                            so it loses some of its buoyancy and allows the chines to be submerged,
                            at least a little. Narrowing the box keel is the preferred solution of
                            course because it will provide greater fuel efficiency and not require
                            a smaller diameter propeller.

                            I've experimented (on the computer) with this concept before, and this
                            design is likely to work well if the hook in the aft bottom is not too
                            extreme, and if the goal of shallow draft is relaxed enough to accept a
                            hull that drafts 14-15 inches rather than 6-7 inches. But my design
                            goal has always been to retain the very shallow draft, so I've not
                            developed this concept further. But outboards require this much draft,
                            so maybe this concept is worth a second look.

                            With a protected propeller and rudder, a boat that drafts 15 inches
                            might still be a desirable boat, especially if it can be as easily
                            driven (fuel efficient) as some of these tunnel-stern Seabright boats
                            seem to be. There is every possibility that such a boat might be even
                            more fuel efficient than the Atkin designs, since they would use a
                            narrower box keel and not have to pump water up into a tunnel pocket.

                            I don't think speeds in excess of 20 or 25 knots are going to be
                            practical and fuel efficient at the same time in a boat like this, but
                            these speeds may be possible -- and when it comes to "running for
                            cover" speed seems to take precedence over fuel efficiency.

                            Sincerely,
                            Ken Grome
                            Bagacay Boatworks
                            www.bagacayboatworks.com
                          • Michael Walther
                            Hi again Ken & Group, The image of the stern post in my momentarily beffuddied brain the angle was 45 degrees, like I said it does that sometimes. I agree,
                            Message 13 of 16 , Apr 7, 2008
                            • 0 Attachment
                              Hi again Ken & Group, The image of the stern post in my momentarily beffuddied brain the angle was 45 degrees, like I said it does that sometimes. I agree, that little bit o'difference is nothing. I disagree about it being a non issue, with high-tech being what it is & interested in everything, I would love to see the results of tank tests for running angle and fuel economy at varying angles fore & aft.(Me design student for second career).
                              I'm glad you sent those links to the pix. A couple of them at stern under early construction were scary. It progressed beautifully;) Two things in particular, #1. The black bottom is real sharp, hope you'll keep it. Being black, detail of the stern was highly visible & looks great. #2. I think the change to bows sheer was brilliant! The perfect curve. It will be spectacular in the water, can't wait to see it.(ya did good)
                              Couple more things, you have a beautiful place (would love to live there), and the carport/porch rail is a great detail, just beautiful. Congrats.
                              Thank, Mike

                              --- On Mon, 4/7/08, Kenneth Grome <bagacayboatworks@...> wrote:

                              > From: Kenneth Grome <bagacayboatworks@...>
                              > Subject: Re: [AtkinBoats] Tolman's adaptation
                              > To: AtkinBoats@yahoogroups.com
                              > Date: Monday, April 7, 2008, 7:56 AM
                              > Hi Mike,
                              >
                              >
                              > > The drawing does show a much taller tunnel and
                              > > your correct about its effects and looking at them
                              > > again I have to say I don't know why my brain saw
                              > > such a steep angle of the stern post, but sometimes
                              > > it does that and it is more angled than Rescue Minors.
                              >
                              >
                              > I hadn't seen that drawing you've been referring to
                              > until a few minutes
                              > ago. It looks similar to the plans I worked from. I know
                              > Renn changed
                              > some things after I started building my hull, but I'm
                              > not sure which
                              > things were changed. Probably not many, and probably
                              > nothing major
                              > since my building of this hull was done specifically to
                              > prove the
                              > validity of the plans he sent me.
                              >
                              >
                              > > As for what difference it would make I don't know
                              > > for sure but I believe it's detrimental.
                              >
                              > I wouldn't call it detrimental. Shortening the flat
                              > box keel bottom and
                              > using an angled stern post will reduce the flat planing
                              > surface, but
                              > the difference is so small that I don't think anyone
                              > would ever notice
                              > it. Basically I think the vertical or angled stern post is
                              > a
                              > non-issue.
                              >
                              >
                              > > The pic I refer to is Renn's boat not yours.
                              > Unless
                              > > Tolman's site site features your boat & not
                              > his.
                              >
                              > Renn doesn't have any of my pictures on his site, and
                              > none of my
                              > pictures are on the fishyfish.com site either. All my
                              > pictures are
                              > here, and they are all photographs, not drawings or
                              > sketches:
                              >
                              > http://www.bagacayboatworks.com/images/seabright01/
                              > http://www.bagacayboatworks.com/images/seabright02/
                              > http://www.bagacayboatworks.com/images/seabright03/
                              >
                              > Sincerely,
                              > Ken Grome
                              > Bagacay Boatworks
                              > www.bagacayboatworks.com
                              >
                              >
                              >
                              >
                              >
                              >
                              >
                              > ------------------------------------
                              >
                              > No flaming, cursing, politics, religion or public mopery.
                              > Please be polite.
                              >
                              > If you set out to build an Atkin boat, please do not modify
                              > the plans. If you stray from the plans you do so at your own
                              > risk and Atkin & Co. will take no responsibility for the
                              > performance of the resulting boat.
                              >
                              > The current Atkin boat plans catalog is online at
                              > <http://www.atkinboatplans.com/>
                              >
                              > Yahoo! Groups Links
                              >
                              >
                              >

                              ____________________________________________________________________________________
                              You rock. That's why Blockbuster's offering you one month of Blockbuster Total Access, No Cost.
                              http://tc.deals.yahoo.com/tc/blockbuster/text5.com
                            • Michael Walther
                              Hi Ken & Group, Your very quick and ahead of me here. I will need some time to make sure I understand everything your saying. As far as I can tell now, you are
                              Message 14 of 16 , Apr 7, 2008
                              • 0 Attachment
                                Hi Ken & Group, Your very quick and ahead of me here. I will need some time to make sure I understand everything your saying. As far as I can tell now, you are very close. I will get back to you soon. Thanks, Mike


                                --- On Mon, 4/7/08, Kenneth Grome <bagacayboatworks@...> wrote:

                                > From: Kenneth Grome <bagacayboatworks@...>
                                > Subject: Re: [AtkinBoats] Re: Tolman's adaptation
                                > To: AtkinBoats@yahoogroups.com
                                > Date: Monday, April 7, 2008, 11:32 AM
                                > > My idea would be to incorporate & blend a
                                > > V into the forward half only, leaving last half
                                > > flat for a softer ride in the rougher water of
                                > > the Potomac & Cheasapeake.
                                >
                                >
                                > I would like to understand what you're suggesting here,
                                > and I'm not sure
                                > I 'get it' just yet ...
                                >
                                > Do you mean to design the front half of the boat more or
                                > less like the
                                > Tolman Seabright skiff is designed now -- but instead of
                                > twisting the
                                > garboard panels so that they become an inverted vee in the
                                > aft tunnel
                                > section behind the end of the box keel, these garboard
                                > panels would
                                > instead twist only enough so that they will end up
                                > horizontal in the
                                > athwartship direction -- possibly while retaining the
                                > downward 'hook'
                                > of the bottom at the transom?
                                >
                                > If this is what you mean, the aft chines will remain above
                                > the water
                                > when the boat is at rest, offering no lateral stability
                                > over what the
                                > pirogue-shaped box keel and the center / front portion of
                                > the hull
                                > provides -- which is not much relatively speaking. The
                                > simple solution
                                > here is to reduce the height of the box keel, or better yet
                                > narrow it
                                > so it loses some of its buoyancy and allows the chines to
                                > be submerged,
                                > at least a little. Narrowing the box keel is the preferred
                                > solution of
                                > course because it will provide greater fuel efficiency and
                                > not require
                                > a smaller diameter propeller.
                                >
                                > I've experimented (on the computer) with this concept
                                > before, and this
                                > design is likely to work well if the hook in the aft bottom
                                > is not too
                                > extreme, and if the goal of shallow draft is relaxed enough
                                > to accept a
                                > hull that drafts 14-15 inches rather than 6-7 inches. But
                                > my design
                                > goal has always been to retain the very shallow draft, so
                                > I've not
                                > developed this concept further. But outboards require this
                                > much draft,
                                > so maybe this concept is worth a second look.
                                >
                                > With a protected propeller and rudder, a boat that drafts
                                > 15 inches
                                > might still be a desirable boat, especially if it can be as
                                > easily
                                > driven (fuel efficient) as some of these tunnel-stern
                                > Seabright boats
                                > seem to be. There is every possibility that such a boat
                                > might be even
                                > more fuel efficient than the Atkin designs, since they
                                > would use a
                                > narrower box keel and not have to pump water up into a
                                > tunnel pocket.
                                >
                                > I don't think speeds in excess of 20 or 25 knots are
                                > going to be
                                > practical and fuel efficient at the same time in a boat
                                > like this, but
                                > these speeds may be possible -- and when it comes to
                                > "running for
                                > cover" speed seems to take precedence over fuel
                                > efficiency.
                                >
                                > Sincerely,
                                > Ken Grome
                                > Bagacay Boatworks
                                > www.bagacayboatworks.com
                                >
                                >
                                >
                                >
                                >
                                >
                                >
                                > ------------------------------------
                                >
                                > No flaming, cursing, politics, religion or public mopery.
                                > Please be polite.
                                >
                                > If you set out to build an Atkin boat, please do not modify
                                > the plans. If you stray from the plans you do so at your own
                                > risk and Atkin & Co. will take no responsibility for the
                                > performance of the resulting boat.
                                >
                                > The current Atkin boat plans catalog is online at
                                > <http://www.atkinboatplans.com/>
                                >
                                > Yahoo! Groups Links
                                >
                                >
                                >

                                ____________________________________________________________________________________
                                You rock. That's why Blockbuster's offering you one month of Blockbuster Total Access, No Cost.
                                http://tc.deals.yahoo.com/tc/blockbuster/text5.com
                              • Ronald Fossum
                                Ayep! And when you do a split or full tunnel hull, you can use a sternwheel , but tucked between the two hulls aft (sort of like an inside quarterwheel) and
                                Message 15 of 16 , Apr 7, 2008
                                • 0 Attachment
                                  Ayep! And when you do a split or full tunnel hull, you can use a "sternwheel", but tucked between the two hulls aft (sort of like an "inside" quarterwheel) and be able to do shallow draft and protect the "propeller" as well.

                                  Ron
                                  Just because it was designed later doesn't mean it was designed better!

                                  ----- Original Message -----
                                  From: Kenneth Grome
                                  To: AtkinBoats@yahoogroups.com
                                  Sent: Monday, April 07, 2008 3:46 AM
                                  Subject: Re: [AtkinBoats] More thoughts on tunnel-stern Seabright skiffs ...


                                  > William was 61 when he designed "River Belle" in 1943 - does anyone
                                  > know how many other Tunnel Stern designs came after that period or
                                  > where the chronology of his designs can be found ? Not that I have a
                                  > vested interest of course....

                                  I asked about the chronology previously in this group, and someone
                                  posted the info I've been using and relating to others. The same info
                                  is probably still in the list archives.

                                  Dave Gerr designed some larger boats using tunnel-sterns but apparently
                                  they do not match the efficiency of the smaller Atkin designs. This
                                  (and my gut instinct) tells me the advantages of the larger
                                  tunnel-stern designs such as River Belle come more from their protected
                                  propellers and shallow draft than their greater fuel efficiency.

                                  I think multihulls are a better bet in terms of efficiency when boats
                                  the length of River Belle or longer are concerned. They provide more
                                  livable space too.

                                  Sincerely,
                                  Ken Grome
                                  Bagacay Boatworks
                                  www.bagacayboatworks.com





                                  [Non-text portions of this message have been removed]
                                • Michael Walther
                                  Hi Ken & Group, I should have been more clear (my bad). Here s hoping I get it right this time. The change involves the bottom of the box keel only. Any change
                                  Message 16 of 16 , Apr 7, 2008
                                  • 0 Attachment
                                    Hi Ken & Group, I should have been more clear (my bad). Here's hoping I get it right this time. The change involves the bottom of the box keel only. Any change to the stern would be to raise bottom of transom center a maximum of half in. but not top of tunnel over prop changing the angle of descent, any cavitation would happen at slowest speeds.
                                    The increase in draft isn't really that important. The Potomac's channel is on average 25' plus deep & wide, the in-town Naval base on the Anacostia River is 10-15 blocks (maybe less than that) from Capital building and for city's security it must be able to handle war ships 2oo ft plus. The shallow parts are full of quickly shifting sand bars some Rescue Minor would have trouble clearing.
                                    My real interest is River Belle as in-town on the Potomac live aboard retirement & economical large distance cruising. My interest Rescue Minor was sparked by Robb Whites article in WB mag.#189 and thoughts of Rescue Minor as day tripper with friends.
                                    Thanks, Mike

                                    --- On Mon, 4/7/08, Kenneth Grome <bagacayboatworks@...> wrote:

                                    > From: Kenneth Grome <bagacayboatworks@...>
                                    > Subject: Re: [AtkinBoats] Re: Tolman's adaptation
                                    > To: AtkinBoats@yahoogroups.com
                                    > Date: Monday, April 7, 2008, 11:32 AM
                                    > > My idea would be to incorporate & blend a
                                    > > V into the forward half only, leaving last half
                                    > > flat for a softer ride in the rougher water of
                                    > > the Potomac & Cheasapeake.
                                    >
                                    >
                                    > I would like to understand what you're suggesting here,
                                    > and I'm not sure
                                    > I 'get it' just yet ...
                                    >
                                    > Do you mean to design the front half of the boat more or
                                    > less like the
                                    > Tolman Seabright skiff is designed now -- but instead of
                                    > twisting the
                                    > garboard panels so that they become an inverted vee in the
                                    > aft tunnel
                                    > section behind the end of the box keel, these garboard
                                    > panels would
                                    > instead twist only enough so that they will end up
                                    > horizontal in the
                                    > athwartship direction -- possibly while retaining the
                                    > downward 'hook'
                                    > of the bottom at the transom?
                                    >
                                    > If this is what you mean, the aft chines will remain above
                                    > the water
                                    > when the boat is at rest, offering no lateral stability
                                    > over what the
                                    > pirogue-shaped box keel and the center / front portion of
                                    > the hull
                                    > provides -- which is not much relatively speaking. The
                                    > simple solution
                                    > here is to reduce the height of the box keel, or better yet
                                    > narrow it
                                    > so it loses some of its buoyancy and allows the chines to
                                    > be submerged,
                                    > at least a little. Narrowing the box keel is the preferred
                                    > solution of
                                    > course because it will provide greater fuel efficiency and
                                    > not require
                                    > a smaller diameter propeller.
                                    >
                                    > I've experimented (on the computer) with this concept
                                    > before, and this
                                    > design is likely to work well if the hook in the aft bottom
                                    > is not too
                                    > extreme, and if the goal of shallow draft is relaxed enough
                                    > to accept a
                                    > hull that drafts 14-15 inches rather than 6-7 inches. But
                                    > my design
                                    > goal has always been to retain the very shallow draft, so
                                    > I've not
                                    > developed this concept further. But outboards require this
                                    > much draft,
                                    > so maybe this concept is worth a second look.
                                    >
                                    > With a protected propeller and rudder, a boat that drafts
                                    > 15 inches
                                    > might still be a desirable boat, especially if it can be as
                                    > easily
                                    > driven (fuel efficient) as some of these tunnel-stern
                                    > Seabright boats
                                    > seem to be. There is every possibility that such a boat
                                    > might be even
                                    > more fuel efficient than the Atkin designs, since they
                                    > would use a
                                    > narrower box keel and not have to pump water up into a
                                    > tunnel pocket.
                                    >
                                    > I don't think speeds in excess of 20 or 25 knots are
                                    > going to be
                                    > practical and fuel efficient at the same time in a boat
                                    > like this, but
                                    > these speeds may be possible -- and when it comes to
                                    > "running for
                                    > cover" speed seems to take precedence over fuel
                                    > efficiency.
                                    >
                                    > Sincerely,
                                    > Ken Grome
                                    > Bagacay Boatworks
                                    > www.bagacayboatworks.com
                                    >
                                    >
                                    >
                                    >
                                    >
                                    >
                                    >
                                    > ------------------------------------
                                    >
                                    > No flaming, cursing, politics, religion or public mopery.
                                    > Please be polite.
                                    >
                                    > If you set out to build an Atkin boat, please do not modify
                                    > the plans. If you stray from the plans you do so at your own
                                    > risk and Atkin & Co. will take no responsibility for the
                                    > performance of the resulting boat.
                                    >
                                    > The current Atkin boat plans catalog is online at
                                    > <http://www.atkinboatplans.com/>
                                    >
                                    > Yahoo! Groups Links
                                    >
                                    >
                                    >

                                    ____________________________________________________________________________________
                                    You rock. That's why Blockbuster's offering you one month of Blockbuster Total Access, No Cost.
                                    http://tc.deals.yahoo.com/tc/blockbuster/text5.com
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