## scaling up a boat?

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• Trying to get a grasp of how to exactly scale up a boat from existing plans. Say for a 30% enlargement would i just multiply everything by 1.3 including the 12
Message 1 of 23 , Mar 3, 2004
Trying to get a grasp of how to exactly scale up a boat from
existing plans.
Say for a 30% enlargement would i just multiply everything by 1.3
including the 12 inches between station lines?
Been thinking of scaling up a nymph or a elegant punt if i don't
build an oldshoe. I know i would need to beef up the framing a bit
but that seems easy enough.
Bought a really neat little contractor's calculator that does math
in feet, inches, quarters, eights, sixteenths and
thirtyseconds....it just got me thinking.
Thanks, Jason Stancil
• Yes, and no. Note that adding 30% to the linear dimensions doubles the volume. Surface area is 70% greater. Stiffness is some high power of the thickness
Message 2 of 23 , Mar 3, 2004
Yes, and no.

Note that adding 30% to the linear dimensions doubles the volume. Surface
area is 70% greater. Stiffness is some high power of the thickness (figure
the beam's moment of inertia, but that was 50 years ago), so scantlings are
????

Drop a kitten six feet and he grins, drop an elephant the same difference
and you have a mess to clean up.

Roger
derbyrm at starband.net
http://derbyrm.mystarband.net

----- Original Message -----
From: "smithriverranger" <jasonstancil@...>
To: <bolger@yahoogroups.com>
Sent: Wednesday, March 03, 2004 5:27 PM
Subject: [bolger] scaling up a boat?

> Trying to get a grasp of how to exactly scale up a boat from
> existing plans.
> Say for a 30% enlargement would i just multiply everything by 1.3
> including the 12 inches between station lines?
> Been thinking of scaling up a nymph or a elegant punt if i don't
> build an oldshoe. I know i would need to beef up the framing a bit
> but that seems easy enough.
> Bought a really neat little contractor's calculator that does math
> in feet, inches, quarters, eights, sixteenths and
> thirtyseconds....it just got me thinking.
> Thanks, Jason Stancil
• so avoid building an elephant? ... doubles the volume. Surface ... the thickness (figure ... ago), so scantlings are ... elephant the same difference ... boat
Message 3 of 23 , Mar 3, 2004
so avoid building an elephant?
--- derbyrm@... <derbyrm@...> wrote:
> Yes, and no.
>
> Note that adding 30% to the linear dimensions
doubles the volume. Surface
> area is 70% greater. Stiffness is some high power of
the thickness (figure
> the beam's moment of inertia, but that was 50 years
ago), so scantlings are
> ????
>
> Drop a kitten six feet and he grins, drop an
elephant the same difference
> and you have a mess to clean up.
>
> Roger
> derbyrm at starband.net
> http://derbyrm.mystarband.net
>
> ----- Original Message -----
> From: "smithriverranger" <jasonstancil@...>
> To: <bolger@yahoogroups.com>
> Sent: Wednesday, March 03, 2004 5:27 PM
> Subject: [bolger] scaling up a boat?
>
>
> > Trying to get a grasp of how to exactly scale up a
boat from
> > existing plans.
> > Say for a 30% enlargement would i just multiply
everything by 1.3
> > including the 12 inches between station lines?
> > Been thinking of scaling up a nymph or a elegant
punt if i don't
> > build an oldshoe. I know i would need to beef up
the framing a bit
> > but that seems easy enough.
> > Bought a really neat little contractor's
calculator that does math
> > in feet, inches, quarters, eights, sixteenths and
> > thirtyseconds....it just got me thinking.
> > Thanks, Jason Stancil
>
>
>
>
> Bolger rules!!!
> - no cursing, flaming, trolling, spamming, or
> - stay on topic, stay on thread, punctuate, no 'Ed,
thanks, Fred' posts
and snip away
> - Plans: Mr. Philip C. Bolger, P.O. Box 1209,
Gloucester, MA, 01930, Fax: (978) 282-1349
> - Unsubscribe: bolger-unsubscribe@yahoogroups.com
> - Open discussion:
bolger_coffee_lounge-subscribe@yahoogroups.com
>
>
> bolger-unsubscribe@yahoogroups.com
>
>
• ... yup........especially white ones........:-) Peter Lenihan
Message 4 of 23 , Mar 3, 2004
--- In bolger@yahoogroups.com, Don Tyson <tysond99@y...> wrote:
> so avoid building an elephant?

yup........especially white ones........:-)

Peter Lenihan
• I ve read about how the volume increases significantly with a slight increase in scale, but that s the point the current boat as drawn is too small. I m
Message 5 of 23 , Mar 3, 2004
increase in scale, but that's the point the current boat as drawn is
too small. I'm talking about scaling up an 8' boat to 10'......no
elephant here.
Thanks for the input,
Jason Stancil

--- In bolger@yahoogroups.com, "Roger Derby" <derbyrm@s...> wrote:
> Yes, and no.
>
> Note that adding 30% to the linear dimensions doubles the volume.
Surface
> area is 70% greater. Stiffness is some high power of the thickness
(figure
> the beam's moment of inertia, but that was 50 years ago), so
scantlings are
> ????
>
> Drop a kitten six feet and he grins, drop an elephant the same
difference
> and you have a mess to clean up.
>
> Roger
> derbyrm at starband.net
> http://derbyrm.mystarband.net
>
> ----- Original Message -----
> From: "smithriverranger" <jasonstancil@h...>
> To: <bolger@yahoogroups.com>
> Sent: Wednesday, March 03, 2004 5:27 PM
> Subject: [bolger] scaling up a boat?
>
>
> > Trying to get a grasp of how to exactly scale up a boat from
> > existing plans.
> > Say for a 30% enlargement would i just multiply everything by 1.3
> > including the 12 inches between station lines?
> > Been thinking of scaling up a nymph or a elegant punt if i don't
> > build an oldshoe. I know i would need to beef up the framing a
bit
> > but that seems easy enough.
> > Bought a really neat little contractor's calculator that does
math
> > in feet, inches, quarters, eights, sixteenths and
> > thirtyseconds....it just got me thinking.
> > Thanks, Jason Stancil
• ... slight ... is ... Jason, Maybe,just maybe,since you are refering to a very basic shape and only wish to add two feet to her length,then you might be able
Message 6 of 23 , Mar 3, 2004
--- In bolger@yahoogroups.com, "smithriverranger" <jasonstancil@h...>
wrote:
slight
> increase in scale, but that's the point the current boat as drawn
is
> too small. I'm talking about scaling up an 8' boat to 10'......no
> elephant here.
> Thanks for the input,
> Jason Stancil

Jason,
Maybe,just maybe,since you are refering to a very basic shape and
only wish to add two feet to her length,then you might be able to do
just that without touching any of the other dimensions.
This would,of course, require some extra waste in plywood and your
willingness to"loft" the expanded side panels out to a length needed
for a 10 foot version.Everything else,like the transom and frames
would remain pretty much as is.
Try it out,to the same scale as on the plans, with a model made
out of some heavy construction paper(cardboard) and see if you like
the looks ....adjust to taste :-)

Sincerely,

Peter Lenihan
• ... Up to 20% is typically OK, just move the stations further apart. Scows are a different case as are sharpies and you can scale up more. A scow is a scow
Message 7 of 23 , Mar 4, 2004
>increase in scale, but that's the point the current boat as drawn is
>too small. I'm talking about scaling up an 8' boat to 10'......no
>elephant here.
>Thanks for the input,
>Jason Stancil

Up to 20% is typically OK, just move the stations further apart. Scows are
a different case as are sharpies and you can "scale up" more. A scow is a
scow is a scow.
--
Craig O'Donnell
Sinepuxent Ancestors & Boats
<http://freepages.genealogy.rootsweb.com/~fassitt/>
Sailing Canoes, Polytarp Sails, Bamboo, Chinese Junks,
American Proas, the Bolger Boat Honor Roll,
Plywood Boats, Bamboo Rafts, &c.
_________________________________

-- Professor of Boatology -- Junkomologist
-- Macintosh kinda guy
Friend of Wanda the Wonder Cat, 1991-1997.
_________________________________
• I am building Howard Chappelle s 18 Camp Skiff . I have lofted the major lines and have the molds done and I am now struggling with the transom. How does one
Message 8 of 23 , Mar 4, 2004
I am building Howard Chappelle's 18' "Camp Skiff". I have lofted the
major lines and have the molds done and I am now struggling with the
transom. How does one loft the side panels? or does your note only
apply to previously expanded panels a la Bolger instant boats?
Bob Chamberland

--- In bolger@yahoogroups.com, "Peter Lenihan" <lestat@b...> wrote:
> This would,of course, require some extra waste in plywood and your
> willingness to"loft" the expanded side panels out to a length needed
> for a 10 foot version.Everything else,like the transom and frames
> would remain pretty much as is.

> Peter Lenihan
• ... Hi Bob, I was refering only to the expanded panels that Bolger usually shows for his plywood hulls. I m not familiar with Camp Skiff but if it is a
Message 9 of 23 , Mar 4, 2004
--- In bolger@yahoogroups.com, cha62759@t... wrote:
> I am building Howard Chappelle's 18' "Camp Skiff". I have lofted the
> major lines and have the molds done and I am now struggling with the
> transom. How does one loft the side panels? or does your note only
> apply to previously expanded panels a la Bolger instant boats?
> Bob Chamberland

Hi Bob,
I was refering only to the "expanded" panels that Bolger
usually shows for his plywood hulls.
I'm not familiar with "Camp Skiff" but if it is a Chappelle
work,does he call for the sides to be out of plywood or just planks?
The full lofting of side "panels" would involve,if I recall,laying
out on the loft floor all the stations and base line.Then using the
information provided in the table of off-sets,for each
frame/station/mold,you plot out the height of the chine and shear for
each.Once all your points are down,lay a fairing batten down and
strike a fair line.The resulting shape should be your"expanded" panel
shape.
you do not need to go back to the table of off-sets.Instead just pick
out the respective heights,for chine and shear,and transfer these to
their respective station lines layed out previously.
This will only work for flat,straight-sided,hulls.If the hull
is round,then you have to figure out the"chain girth" at each
station,divide this figure by the number of planks you intend on
using to get the correct shape of each plank so that the finished
boat does not have all its planks"frowning",ie;with the seams curving
downward,opposite to the sweep of the shearline.......
At any rate,I hope I have it right and haven't forgotten some
critical bit of information.Hopefully,someone who knows better will
jump in and correct my mistakes :-)

Sincerely,

Peter Lenihan
• ... This chain girth question has always confounded me, trying to figure out how to loft a lapstrake or planked boat. Peter, is it as simple as divide by
Message 10 of 23 , Mar 4, 2004
--- Peter Lenihan wrote:
> If the hull is round,
> then you have to figure out the"chain
> girth" at each station, divide this figure
> by the number of planks you intend on
> using to get the correct shape of each plank
> so that the finished boat does not have all its
> planks"frowning",ie;with> the seams curving
> downward,opposite to the sweep of the
> shearline.......

This 'chain girth' question has always
confounded me, trying to figure out how
to loft a lapstrake or planked boat.

Peter, is it as simple as 'divide by the
number of planks'? Because that calculation
only gives you the width of each plank at
each station. [Not the distance of each edge
of the plank from the center line of the plank
at each station.]

In other words, it doesn't give you the
lengthwise curve of the plank, IE, is it
curved like a banana, and just how much?
Spiling, from one plank to the next,
I guess, gives that information.

That is unless, and this is where I get
confused, it appears that the lengthwise
curve of the plank could be 'read' through
the lofting of the 'diagonals' in the lofting
diagram. But I never figured that out.

Lofting the stations, halfbreaths and waterlines
makes sense to me, but lofting the diagonals
does not!
• Rather than try to explain it, let me suggest you get a copy of Ian Oughtred s excellent book on lap ply construction. ... From: Bruce Hallman
Message 11 of 23 , Mar 4, 2004
Rather than try to explain it, let me suggest you get a copy of Ian
Oughtred's excellent book on lap ply construction.

----- Original Message -----
From: "Bruce Hallman" <bruce@...>
To: <bolger@yahoogroups.com>
Sent: Thursday, March 04, 2004 10:43 AM
Subject: Re: [bolger] Re: "Lofting" side panels

> --- Peter Lenihan wrote:
> > If the hull is round,
> > then you have to figure out the"chain
> > girth" at each station, divide this figure
> > by the number of planks you intend on
> > using to get the correct shape of each plank
> > so that the finished boat does not have all its
> > planks"frowning",ie;with> the seams curving
> > downward,opposite to the sweep of the
> > shearline.......
>
> This 'chain girth' question has always
> confounded me, trying to figure out how
> to loft a lapstrake or planked boat.
>
> Peter, is it as simple as 'divide by the
> number of planks'? Because that calculation
> only gives you the width of each plank at
> each station. [Not the distance of each edge
> of the plank from the center line of the plank
> at each station.]
>
> In other words, it doesn't give you the
> lengthwise curve of the plank, IE, is it
> curved like a banana, and just how much?
> Spiling, from one plank to the next,
> I guess, gives that information.
>
> That is unless, and this is where I get
> confused, it appears that the lengthwise
> curve of the plank could be 'read' through
> the lofting of the 'diagonals' in the lofting
> diagram. But I never figured that out.
>
> Lofting the stations, halfbreaths and waterlines
> makes sense to me, but lofting the diagonals
> does not!
>
>
>
>
> Bolger rules!!!
> - no cursing, flaming, trolling, spamming, or flogging dead horses
> - stay on topic, stay on thread, punctuate, no 'Ed, thanks, Fred' posts
> - Plans: Mr. Philip C. Bolger, P.O. Box 1209, Gloucester, MA, 01930, Fax:
(978) 282-1349
> - Unsubscribe: bolger-unsubscribe@yahoogroups.com
> - Open discussion: bolger_coffee_lounge-subscribe@yahoogroups.com
>
>
>
>
>
• My guess is that most boatbuilders will abandon the loftwork as soon as the frames have been fabricated and set up. At that point, it s no longer a matter of
Message 12 of 23 , Mar 4, 2004
My guess is that most boatbuilders will abandon the loftwork as soon
as the frames have been fabricated and set up. At that point, it's no
longer a matter of what the designer had in mind, and more a matter
of what size and shape the frames actually are. In other words, the
shape would be taken from the frames, not from the planking. You
might try to get your hands on the WoodenBoat article on the building
of the Whittholz-designed Downeaster v-bottom powerboat. It shows how
to build a non-instant plywood boat about as well as anything.

I would set up the frames, rightside up, or upside down, as prefered.
To get the shape for the planking, I would take the shape from the
frames by making up a plank about 4" wide that is stiff enough and
pliable enough to make a fair curve. (e.g. 3/8" ply) It should be
long enough to go from stem to stern. Mount it temporarily along the
mid-point of the side plank. Then, at each frame, draw a line across
the 4" piece showing the angle at which the frame crosses it, and
measure the length from some mark to where the edge of the plank
needs to fall, both above and below.

Then to mark the planking, lay the marked piece on the stock. Extend
the lines marking where the frames will cross, and measure to where
the edge needs to fall. You can then draw a fair line along the
edge. ("Voila!," Peter might say.) I would leave an allowance for

This is basically the way a plank would be spiled for lap or carvel
construction. Perhaps you need a book? Chapelle's Boatbuilding or
Sewards' Boatbuilding Manual.

Peter
• Bruce, I, too, languished in ignorance for many years until I was shown the light ( Eureka! ) By Richard Cullison, who was teaching a lofting class at the
Message 13 of 23 , Mar 4, 2004
Bruce,

I, too, languished in ignorance for many years until I was shown the light
("Eureka!") By Richard Cullison, who was teaching a lofting class at the
Chesapeake Bay Maritime Museum (all three have my enthusiastic
recommendations, BTW).

The diagonals are arrived at by starting with the half-breadth lines and
taking the intersections of the diagonal line with each of the frames and
carrying that point over to the profile drawing, where the points are marked
on the frame stations. Spring a batten through those points and trace in
the line. Hey presto, and you've just drawn a diagonal! This line actually
helps define the three-dimensional nature of the lofting process, and you
can add as many as you like to further smooth the frames into line. The
process, once you get your arms around the function, is the magic that makes
lofting work.

traditional building methods (he goes a little overboard, but to be honest,
I get a severe case of inferiority neurosis every time I read one of his
books...).

David Romasco

_____

From: Bruce Hallman [mailto:bruce@...]
Sent: Thursday, March 04, 2004 10:43 AM
To: bolger@yahoogroups.com
Subject: Re: [bolger] Re: "Lofting" side panels

--- Peter Lenihan wrote:
> If the hull is round,
> then you have to figure out the"chain
> girth" at each station, divide this figure
> by the number of planks you intend on
> using to get the correct shape of each plank
> so that the finished boat does not have all its
> planks"frowning",ie;with> the seams curving
> downward,opposite to the sweep of the
> shearline.......

This 'chain girth' question has always
confounded me, trying to figure out how
to loft a lapstrake or planked boat.

Peter, is it as simple as 'divide by the
number of planks'? Because that calculation
only gives you the width of each plank at
each station. [Not the distance of each edge
of the plank from the center line of the plank
at each station.]

In other words, it doesn't give you the
lengthwise curve of the plank, IE, is it
curved like a banana, and just how much?
Spiling, from one plank to the next,
I guess, gives that information.

That is unless, and this is where I get
confused, it appears that the lengthwise
curve of the plank could be 'read' through
the lofting of the 'diagonals' in the lofting
diagram. But I never figured that out.

Lofting the stations, halfbreaths and waterlines
makes sense to me, but lofting the diagonals
does not!

Bolger rules!!!
- no cursing, flaming, trolling, spamming, or flogging dead horses
- stay on topic, stay on thread, punctuate, no 'Ed, thanks, Fred' posts
- Plans: Mr. Philip C. Bolger, P.O. Box 1209, Gloucester, MA, 01930, Fax:
(978) 282-1349
- Unsubscribe: bolger-unsubscribe@yahoogroups.com
- Open discussion: bolger_coffee_lounge-subscribe@yahoogroups.com

_____

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[Non-text portions of this message have been removed]
• ... Bruce,with a fairly typical hull shape(narrow and pointy at one end,fat and low in the middle,and slightly narrower and higher at the other end) you will
Message 14 of 23 , Mar 4, 2004
--- In bolger@yahoogroups.com, Bruce Hallman <bruce@h...> wrote:
> Peter, is it as simple as 'divide by the
> number of planks'? Because that calculation
> only gives you the width of each plank at
> each station. [Not the distance of each edge
> of the plank from the center line of the plank
> at each station.]

Bruce,with a fairly typical hull shape(narrow and pointy at one
end,fat and low in the middle,and slightly narrower and higher at the
other end) you will indeed get different widths needed for each
plank.These widths need to be transfered onto your planking
stock,faired up with a batten,and trimmed to those lines.The look of
the plank before offering it up will appear somewhat skinny toward
the stern,swelling in the middle and slightly tappering toward the
stem.
Depending on how much shear is in the hull,alot of adjustment must be
done with the garboard plank to ensure you get the planks off on the
right foot.
You do not have to transfer your chain girth measurements to each and
every plank since,one you have established the number of planks you
will need(sometimes best determined once you know what size planks
are available) and establish the correct shape of your garboard
plank, it is just a simple matter of spiling the rest of your planks
up to the shear.
Some hull shapes,however,will require the use of stealer planks if
they have alot of shape to them(the hull,that is) since your plank
ends will begin to be tapered so much that they are too narrow to
drive a fastening into. Similarly,if you run your planking paralle to
the water line,you'll have to "cheat" a bit toward the ends with long
slivers of planking stock,just to meet the shear(or else have a very
wide shear strake and be prepared to waste a lot of wood).

> Lofting the stations, halfbreaths and waterlines
> makes sense to me, but lofting the diagonals
> does not!

Diagonals are beautiful for really tweeking ones lofting as they give
you yet another means of cross checking the fairness of your
previously laid down lines......very useful right in the turn of the
bilge!

If only I could remember correctly everything I was taught during a
course in lofting so many moons ago:-)

Sincerely,

Peter Lenihan
• Keep in mind that the displacement would go up more than 100%! (Cube of 1.3 is about 2.2) Structural calculations probably not simple, tho I suppose you could
Message 15 of 23 , Mar 4, 2004
Keep in mind that the displacement would go up more than 100%! (Cube of
Structural calculations probably not simple, tho I suppose you could
guesstimate. Panel expansions won't fit on plywood either, so you'll
probably use a lot more wood and maybe have more scarphs to do. Are you
sure you don't like the larger plans that are already available?
Windsprint, Featherwind (is that the name?) , and the Japanese Beach
cruiser come to mind, though I'm sure there are others. Bateau.com and
Michalak have some pramlike boats in a larger size range, too. But of
course, you'd probably be the only one around with an oversized Nymph.
I've seen an article somewhere by Bolger where he considers (and
rejects) a little cruiser based on a scale up of the Nymph.

>Jason Stancil wrote:
>Trying to get a grasp of how to exactly scale up a boat from
>existing plans.
>Say for a 30% enlargement would i just multiply everything by 1.3
>including the 12 inches between station lines?
>Been thinking of scaling up a nymph or a elegant punt if i don't
>build an oldshoe. I know i would need to beef up the framing a bit
>but that seems easy enough.
>Bought a really neat little contractor's calculator that does math
>in feet, inches, quarters, eights, sixteenths and
>thirtyseconds....it just got me thinking.
>Thanks, Jason Stancil
>
>
>
>
>___________________________________
>
• ... You re on to me i m thinking about making a nymph micro cruiser. Can you remember where you saw that bolger article or how i can get my hands on it? More
Message 16 of 23 , Mar 4, 2004
> I've seen an article somewhere by Bolger where he considers (and
> rejects) a little cruiser based on a scale up of the Nymph.

You're on to me i'm thinking about making a nymph micro cruiser. Can
you remember where you saw that bolger article or how i can get my
hands on it? More importantly do you remember why bolger rejected
the idea? I know i could just build a micro or old shoe, but i like
screwing around withthings a working with minimal amount of
directions....assuming i don't compromise safety or totally screw up
why the design originally worked in the first place.

> Structural calculations probably not simple, tho I suppose you
could guesstimate. Panel expansions won't fit on plywood either, so
you'll probably use a lot more wood and maybe have more scarphs to
do.

I'm in no hurry I just enjoy straining my brain on this kind of
stuff.....notice i'm not attempting anything "large"

Are you sure you don't like the larger plans that are already
available? Windsprint, Featherwind (is that the name?), and the
Japanese Beach cruiser come to mind, though I'm sure there are
others.

I like dory and pram hulls.....i've built a michalak boat and they
are well done but....for the most part i find them UGLY, but that's
me. What is the Japanese Beach Cruiser?

> course, you'd probably be the only one around with an oversized
Nymph.

Exactly!...just hope it'll float :)

Thanks for any info on that article,
Jason Stancil
• ... It was in MAIB. As I remember, he felt the design got too fussy, and the cuddy was not big enough for the intended use. Peter
Message 17 of 23 , Mar 4, 2004
> Can
> you remember where you saw that bolger article or how i can get my
> hands on it? More importantly do you remember why bolger rejected
> the idea?

It was in MAIB. As I remember, he felt the design got too fussy, and
the cuddy was not big enough for the intended use.

Peter
• My reading of the discussion is that you do not loft side panels. I understand the spiling process but was hoping perhaps that the accumulated knowledge of
Message 18 of 23 , Mar 4, 2004
My reading of the discussion is that you do not "loft" side panels. I
understand the spiling process but was hoping perhaps that the
accumulated knowledge of this board could tell me how to draw and cut
out one panel from information gained through lofting. I assume that
Mr Bolger uses the computer to arrive at his panel extensions.

The Chappelle camp skiff is a hard chine sharpy stink boat. Think
"Redwing" which is derived from Mr Chappelle's design.

The next question is, what computer program? Is there a relatively
simple program which can take the lofted information and produce the
panel extension?

My last experience with this sort of problem led me to nailing a 4'x
24" panel to the building molds and cutting to fit. This was a
decidedly dicey proposition single handed.

Bob Chamberland
• Hi Peter, This process doesn t result in the expanded panels but rather in the elevation of the hull. It does not represent the curvature of the hull fore
Message 19 of 23 , Mar 4, 2004
Hi Peter,
This process doesn't result in the "expanded" panels" but rather in
the "elevation" of the hull. It does not represent the curvature of
the hull fore and aft.
Bob Chamberland

--- In bolger@yahoogroups.com, "Peter Lenihan" <lestat@b...> wrote:
> Hi Bob,
> I was refering only to the "expanded" panels that Bolger
> usually shows for his plywood hulls.
> I'm not familiar with "Camp Skiff" but if it is a Chappelle
> work,does he call for the sides to be out of plywood or just planks?
> The full lofting of side "panels" would involve,if I recall,laying
> out on the loft floor all the stations and base line.Then using the
> information provided in the table of off-sets,for each
> frame/station/mold,you plot out the height of the chine and shear for
> each.Once all your points are down,lay a fairing batten down and
> strike a fair line.The resulting shape should be your"expanded" panel
> shape.
> you do not need to go back to the table of off-sets.Instead just pick
> out the respective heights,for chine and shear,and transfer these to
> their respective station lines layed out previously.
> This will only work for flat,straight-sided,hulls.
• For that sort of boat, Greg Carlson s Chine Hull Designer works very well. It s free and it generates the panel s expanded shapes.
Message 20 of 23 , Mar 4, 2004
For that sort of boat, Greg Carlson's "Chine Hull Designer" works very well.
It's free and it generates the panel's expanded shapes.
http://www.carlsondesign.com/#Fun_Shareware

It took me some thrashing around to figure out that there are no
user-friendly error messages and that when the help files say six chines
maximum, it means six chines maximum. (I was plotting out the lapstrakes
for Chebacco and that wants seven "chines." I'm happy enough with the
results I got by putting the hull in twice, once with a very broad sheer
strake and once with a very broad garboard strake.)

I decided that it wouldn't run on Win2K, but that was before I realized the
six strake limit, so maybe it will. It works well on Win98SE which my other
two computers use.

It yields files which are ASCII text and can be input to other graphic
programs or printed out and drawn by hand on the plywood. It allows you to
specify the size of your plywood panels and shove the strakes around for
efficient nesting. It also prints out pictures of the pieces.

Roger
derbyrm at starband.net
http://derbyrm.mystarband.net

----- Original Message -----
From: <cha62759@...>

> The Chappelle camp skiff is a hard chine sharpy stink boat. Think
> "Redwing" which is derived from Mr Chappelle's design.
>
> The next question is, what computer program? Is there a relatively
> simple program which can take the lofted information and produce the
> panel extension?
• Right. Not lofted but _expanded_ . Bolger doesn t need a computer for it, either. You can use the method described in Chappelle s Boat Building or get Greg
Message 21 of 23 , Mar 4, 2004
Right. Not lofted but _expanded_ . Bolger doesn't need a computer for it, either. You can
use the method described in Chappelle's 'Boat Building' or get Greg Carlson's free Chine
Hull Designer program.
http://www.carlsondesign.com/hulls.zip

Another option, unless you are really interested in design work, is to send \$65 to Karl
Stambaugh for a thoroughly worked out version.
Mark

cha62759@... wrote:
>
> My reading of the discussion is that you do not "loft" side panels. I
> understand the spiling process but was hoping perhaps that the
> accumulated knowledge of this board could tell me how to draw and cut
> out one panel from information gained through lofting. I assume that
> Mr Bolger uses the computer to arrive at his panel extensions.
>
> The Chappelle camp skiff is a hard chine sharpy stink boat. Think
> "Redwing" which is derived from Mr Chappelle's design.
>
> The next question is, what computer program? Is there a relatively
> simple program which can take the lofted information and produce the
> panel extension?
>
> My last experience with this sort of problem led me to nailing a 4'x
> 24" panel to the building molds and cutting to fit. This was a
> decidedly dicey proposition single handed.
>
> Bob Chamberland
• Fundamentally, the way you determine the shape of flat plywood, which will curve correctly to fit the boat is to break down the surface shape into triangles.
Message 22 of 23 , Mar 5, 2004
Fundamentally, the way you determine the
shape of flat plywood, which will
curve correctly to fit the boat is to
break down the surface shape into
triangles. I think that Sam Rabl first

Jim Mickalak's article at =>

http://marina.fortunecity.com/breakwater/274/2000/0101/

If you dust off your memory of high school
trigonometry, you can also do it relatively

In essence, you know the shape of each quadrahedron
with four corners being:
station 1 chine,
station 1 sheerline,
station 2 chine,
station 2 shearline.

Connect corners diagonally to break it into triangles.
Repeat....

These triangles can then be 'unfolded' into a flat
shape.
• ... Probably MAIB (Messing Around in Boats, and I m sure a bit of web surfing will find the contact info), which I believe sells back issues. I bet if you
Message 23 of 23 , Mar 5, 2004
See below:

>Jason Stancil wrote:
>snip
>You're on to me i'm thinking about making a nymph micro cruiser. Can
>you remember where you saw that bolger article or how i can get my
>hands on it?
>
Probably MAIB (Messing Around in Boats, and I'm sure a bit of web
surfing will find the contact info), which I believe sells back issues.
I bet if you snail mail MAIB they can tell you which issue. Or there may
be indexes on line someplace.

>More importantly do you remember why bolger rejected
>the idea?
>
I don't remember exactly. I seem to recall it might be ok but a boat
designed for that size would be better.

>I know i could just build a micro or old shoe, but i like
>screwing around withthings a working with minimal amount of
>directions....assuming i don't compromise safety or totally screw up
>why the design originally worked in the first place.
>
>
>
> snip
>
>I like dory and pram hulls.....i've built a michalak boat and they
>are well done but....for the most part i find them UGLY, but that's
>me. What is the Japanese Beach Cruiser?
>
>
Japanese Beach Cruiser is in Boats with an Open Mind. Quite pretty, and
it's a pram. Maybe too many chines. I think about 12 feet long, as I
recall. And I think Bolger has some other boats of that sort which might
be worth looking into. Isn't there something called the Supermouse?
(also a pram). One of the boats at bateau.com is a big pram, and not
ugly, IMHO. It's not just you, a lot of Michalak boats are funny looking.

> snip
>
>
>________________________________________________
>
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