Loading ...
Sorry, an error occurred while loading the content.
 

Re: Doubling a Micro Bottom

Expand Messages
  • Paul
    I built my micro with a 1/2 bottom and had no trouble bending the 16 scarfed panel to fit the curve. I decided to make the cabin top 1/2 as well cuz I m a
    Message 1 of 29 , Oct 18, 2011
      I built my micro with a 1/2" bottom and had no trouble bending the 16' scarfed panel to fit the curve. I decided to make the cabin top 1/2" as well cuz I'm a big heavy guy and don't want to worry about where to step when I climb up there to wrestle with the mast. When I saw it would be impossible to get 1/2" ply to take that smaller radius curve, I laid it up in 2 layers of 1/4" marine plywood. I glued and screwed the first layer to the frame, and after it set up I laid the second layer on top over a generous slathering of thickened epoxy. I trimmed, sanded, and glassed it, and it's rock solid.

      I had the advantage of working on the horizontal so the goop stayed where I spread it and I could use weight to hold the top layer down while it set up. Since your boat is finished and flipping it would be a big headache, you'll probably have to figure out how to do all this upside-down. Maybe work out a way to vacuum-bag it?

      Paul L. on Cape Cod


      --- In bolger@yahoogroups.com, "Kendall" <ken_j_@...> wrote:
      >
      > I just picked up my micro navigator over the weekend...
    • prairiedog2332
      Kendall, If you can get the boat on it s side, as described by Myles, a possible option might be to add a layer of fiberglass mat instead of plywood.
      Message 2 of 29 , Oct 19, 2011

        Kendall,

        If you can get the boat on it's side, as described by Myles, a possible option might be to add a layer of fiberglass mat instead of plywood. Description here:

        http://www.noahsboatbuilding.com/noahmain/itemdesc.asp?ic=1X38&eq=&Tp=

        It soaks up a lot of resin but polyester will work with it. Then it is faired using bondo and can be glassed over with regular cloth. I had a sailing skiff that the outside of the hull was re-done that way due to checking and does work. Adds a considerable amount of weight but that is not a problem on a Micro.

        I think Allan Vaites has a book out about doing that.

        Nels


        --- In bolger@yahoogroups.com, "Kendall" <ken_j_@...> wrote:
        >
        > I just picked up my micro navigator over the weekend. The bottom of the boat is built to plans at 1/4" plywood and it has been patched a couple of times and is checking in places. I was wanting to get the bottom to 12" minimum or possibly 3/4" or 1" anyway. Can I epoxy some new plywood directly to the existing and then glass over that or should I remove what's there and start from scratch? The bottom is solid with out any soft spots and once I get all the paint removed I will do an inspection and replace any questionable sections if found. My reason for doubling the bottom is that I sail in a water reservoir and the level is constantly changing. It's a man made and there are lots of submerged trees that can get to just below the surface during low water periods.
        >

      • Mark Albanese
        ... Installing it in the first place took great care, no doubt. But properly supported now, why worry? People work underneath much heavier cars and trucks up
        Message 3 of 29 , Oct 19, 2011

          If it were me, I would seriously consider any way imaginable to avoid
          working upside down, and/or working with that 420lbs slug of lead over
          my head!


          Installing it in the first place took great care, no doubt. But properly supported now, why worry? People work underneath much heavier cars and trucks up on jack stands every day. I never got under there myself unless able to give it all a strong kick and a shove without incident.

          The problem with glassing overhead is getting it into your eyes! Yet Myles description of turning a Micro, let alone a Navigator, seems risky enough to me to avoid if possible. Quote here from the System 3 Epoxy Book. 

          "Applying fiberglass overhead is at best a difficult, messy job. Anyone who has tried it once has no desire to repeat the experience and will do everything possible to try to turn the boat over or at least work on a slant. If this is not possible here are several suggestions for accomplishing this job:

          If you are working on a relatively small area, wet the surface with mixed resin/hardener and lay a rough cut piece of cloth into the resin. Surface tension will hold it into place without sagging if too much resin is not used. Using a squeegee overhead is a feat no one has yet mastered. Use foam rollers. Once the epoxy has cured you finish the overhead area in the usual manner.

          Glassing large overhead areas calls for a different technique and a helper or two. Most successful jobs are done by rolling on a coating, then allowing it to cure to a tacky state. The cloth is then rolled as smoothly as possible onto the tacky coating. This is where you'll probably need more than one person. Get the wrinkles out as you go along, you won't be able to slide them out because the tackiness of the coating will hold the cloth in place. Once you've got the cloth where you want it press it into the tacky undercoat with a dry foam roller. When it is all smushed down, wet it out using the roller cover and a roller pan. Use just enough epoxy to wet out the cloth. When cured finish in the usual way.





        • prairiedog2332
          Here is a link to the Vaitses book. The spelling was incorrect in the previous post. http://www.amazon.ca/Fiberglass-Boat-Repair-Manual/dp/0071569146
          Message 4 of 29 , Oct 19, 2011

            Here is a link to the Vaitses' book. The spelling was incorrect in the previous post.

            http://www.amazon.ca/Fiberglass-Boat-Repair-Manual/dp/0071569146

            The method has been roundly criticised when used on large traditionaly planked hulls, but on a small plywood boat there are not the same issues to deal with.


            --- In bolger@yahoogroups.com, "prairiedog2332" <arvent@...> wrote:
            >
            >
            > Kendall,
            >
            > If you can get the boat on it's side, as described by Myles, a possible
            > option might be to add a layer of fiberglass mat instead of plywood.
            > Description here:
            >
            > http://www.noahsboatbuilding.com/noahmain/itemdesc.asp?ic=1X38&eq=&Tp
            > <http://www.noahsboatbuilding.com/noahmain/itemdesc.asp?ic=1X38&eq=&Tp>
            > =
            >
            > It soaks up a lot of resin but polyester will work with it. Then it is
            > faired using bondo and can be glassed over with regular cloth. I had a
            > sailing skiff that the outside of the hull was re-done that way due to
            > checking and does work. Adds a considerable amount of weight but that is
            > not a problem on a Micro.
            >
            > I think Allan Vaites has a book out about doing that.
            >
            > Nels

          • prairiedog2332
            Right author but wrong book. http://www.amazon.com/Covering-Wooden-Boats-Fiberglass-Vaitses/dp/087742 9979/ref=sr_1_3?s=books&ie=UTF8&qid=1319056141&sr=1-3
            Message 5 of 29 , Oct 19, 2011

              Right author but wrong book.

              http://www.amazon.com/Covering-Wooden-Boats-Fiberglass-Vaitses/dp/0877429979/ref=sr_1_3?s=books&ie=UTF8&qid=1319056141&sr=1-3

              Seems it may be out of print now?


              --- In bolger@yahoogroups.com, "prairiedog2332" <arvent@...> wrote:
              >
              >
              > Here is a link to the Vaitses' book. The spelling was incorrect in the
              > previous post.
              >
              > http://www.amazon.ca/Fiberglass-Boat-Repair-Manual/dp/0071569146
              > <http://www.amazon.ca/Fiberglass-Boat-Repair-Manual/dp/0071569146>
              >
              > The method has been roundly criticised when used on large traditionaly
              > planked hulls, but on a small plywood boat there are not the same issues
              > to deal with.
              >
              >
              > --- In bolger@yahoogroups.com, "prairiedog2332" arvent@ wrote:
              > >
              > >
              > > Kendall,
              > >
              > > If you can get the boat on it's side, as described by Myles, a
              > possible
              > > option might be to add a layer of fiberglass mat instead of plywood.
              > > Description here:
              > >
              > > http://www.noahsboatbuilding.com/noahmain/itemdesc.asp?ic=1X38&eq=&Tp
              > >
              > <http://www.noahsboatbuilding.com/noahmain/itemdesc.asp?ic=1X38&eq=&Tp>
              > > =
              > >
              > > It soaks up a lot of resin but polyester will work with it. Then it is
              > > faired using bondo and can be glassed over with regular cloth. I had a
              > > sailing skiff that the outside of the hull was re-done that way due to
              > > checking and does work. Adds a considerable amount of weight but that
              > is
              > > not a problem on a Micro.
              > >
              > > I think Allan Vaites has a book out about doing that.
              > >
              > > Nels
              >

            • David
              My experience is that even small laminations are not as easy as they look. I managed to get voids gluing a rudder lamination. I hate to think of a full bottom.
              Message 6 of 29 , Oct 19, 2011
                My experience is that even small laminations are not as easy as they look. I managed to get voids gluing a rudder lamination. I hate to think of a full bottom. Weights were no good and screws make lots of holes. It seems much glue is called for.

                A neat solution would be to use a vacuum bag (as used by Nexus Marine building the Black Skimmer - http://www.nexusmarine.com/skimmer_construction.html)

                However, I tend to agree that if it's strength you are after with a reasonable sound structure, at this stage in the life of the boat, it is probably better to fibreglass the bottom (which you can do in halfs - from each side of the keel case round to over the chine).

                If the boat is rotten or severely damaged (I seem to remember a quote somewhere about Bernie Wolfard having to replace the floor of his Micro), that might be the way to go. Just take the floor off completely and rebuild from there down. In that case I would just go for the thickness of floor you intend to use. (I built Oldshoe with a 3/8" floor) Up to 1/2" is probably manageable with help and patience for Micro. Still a lot of work and you will definitely want her upside down... Where do you leave the cabin?...

                David


                --- In bolger@yahoogroups.com, "Kendall" <ken_j_@...> wrote:
                >
                > I just picked up my micro navigator over the weekend. The bottom of the boat is built to plans at 1/4" plywood and it has been patched a couple of times and is checking in places. I was wanting to get the bottom to 12" minimum or possibly 3/4" or 1" anyway. Can I epoxy some new plywood directly to the existing and then glass over that or should I remove what's there and start from scratch? The bottom is solid with out any soft spots and once I get all the paint removed I will do an inspection and replace any questionable sections if found. My reason for doubling the bottom is that I sail in a water reservoir and the level is constantly changing. It's a man made and there are lots of submerged trees that can get to just below the surface during low water periods.
                >
              • prairiedog2332
                If I recall, Vaitses method for applying the mat to a hull was to staple it in place first prior to applying the resin and leave them in, obviously not that
                Message 7 of 29 , Oct 19, 2011
                  If I recall, Vaitses' method for applying the mat to a hull was to
                  staple it in place first prior to applying the resin and leave them in,
                  obviously not that practical on a 1/4 inch bottom, as you would end up
                  with a pincushion inside the hull.

                  I also recall a discussion one time regarding using non-metallic polymer
                  staples. The protruding ends could be easily cut or sanded inside the
                  hull I would think.

                  http://www.raptornails.com/catalog_staples.php

                  This might be "doable" if the boat could laid on it's side and the resin
                  rolled in firmly to fill potential gaps. I know with my skiff it never
                  showed any signs of delamination on the outer hull after several years.
                  The dagger board housing split when I grounded a few times, water froze
                  inside it and it began to leak so I gave it away. The next owner removed
                  it and converted it to a motor boat. Still going the last I heard:-)




                  --- In bolger@yahoogroups.com, "David" <dir_cobb@...> wrote:
                  >
                  > My experience is that even small laminations are not as easy as they
                  look. I managed to get voids gluing a rudder lamination. I hate to think
                  of a full bottom. Weights were no good and screws make lots of holes. It
                  seems much glue is called for.
                • Paul T.
                  IIRC, Vaitses used staples because at that time he was using POLYESTER resin which ,unlike epoxy, is a POOR adhesive. Paul T. (who, many years ago, used
                  Message 8 of 29 , Oct 20, 2011
                    IIRC, Vaitses used staples because at that time he was using POLYESTER resin which ,unlike epoxy, is a POOR adhesive.

                    Paul T. (who, many years ago, used polyester both with and without staples--neither of which was really satisfactory)

                    --- In bolger@yahoogroups.com, "prairiedog2332" <arvent@...> wrote:
                    >
                    > If I recall, Vaitses' method for applying the mat to a hull was to
                    > staple it in place first prior to applying the resin and leave them in,
                    > obviously not that practical on a 1/4 inch bottom, as you would end up
                    > with a pincushion inside the hull.
                    >
                    > I also recall a discussion one time regarding using non-metallic polymer
                    > staples. The protruding ends could be easily cut or sanded inside the
                    > hull I would think.
                    >
                    > http://www.raptornails.com/catalog_staples.php
                    >
                    > This might be "doable" if the boat could laid on it's side and the resin
                    > rolled in firmly to fill potential gaps. I know with my skiff it never
                    > showed any signs of delamination on the outer hull after several years.
                    > The dagger board housing split when I grounded a few times, water froze
                    > inside it and it began to leak so I gave it away. The next owner removed
                    > it and converted it to a motor boat. Still going the last I heard:-)
                    >
                    >
                    >
                    >
                    > --- In bolger@yahoogroups.com, "David" <dir_cobb@> wrote:
                    > >
                    > > My experience is that even small laminations are not as easy as they
                    > look. I managed to get voids gluing a rudder lamination. I hate to think
                    > of a full bottom. Weights were no good and screws make lots of holes. It
                    > seems much glue is called for.
                    >
                  • BruceHallman
                    ... I agree that the clamping of a laminate is very tricky. I was surprised and pleased that the lamination process of the bottom of the Topaz Spyder went
                    Message 9 of 29 , Oct 20, 2011
                      On Wed, Oct 19, 2011 at 8:16 PM, David <dir_cobb@...> wrote:
                      >
                      >
                      >
                      > My experience is that even small laminations are not as easy as they look. I managed to get voids gluing a rudder lamination. I hate to think of a full bottom. Weights were no good and screws make lots of holes. It seems much glue is called for.


                      I agree that the clamping of a laminate is very tricky. I was
                      surprised and pleased that the lamination process of the bottom of the
                      Topaz Spyder went very smoothly. (Vacuum bag might also work fine
                      too.)

                      Here is how I did it with Topaz Spyder: The overall hull bottom is 1
                      inch thick, made up of two layers of 1/2" plywood. Averaging about
                      6-7 feet wide by 31 feet overall long. The top and bottom layers were
                      staggered by two feet so the joints were staggered.

                      1) I positioned the bottom layer on the strong back.
                      2) Then I made a batch of about 1 quart of epoxy, and poured it on 2
                      feet of the lower plywood and on 2 feet of the top piece, then spread
                      it around with an 10 inch metal 'drywall taping blade.
                      3) I then flipped the top piece and mated the wet glue face to face.
                      4) Taking two hammers, a carpenters hammer in my right hand, and a 3
                      pound maul in my left hand (held underneath as a 'backer' to keep the
                      wood from bouncing), I nailed the two pieces together using 7/8" #14
                      silicon bronze ring shank nails at about 10 inch centers.

                      I am confident that there were zero voids, as the ring shanks cinched
                      up real tight. The silicon bronze has the advantage that it is just
                      soft enough that you could then follow up with a pass over using a
                      belt sander without eating up the belts, to get things smoothed up for
                      the surface fiberglass lamination that follows.

                      For this reason, I am worried about laminating two sheets of 1/4"
                      plywood, as it it too thin to accept ring shank nails. Two sheets of
                      1/2" work fine, great even. It was surprising to see how the 2ft
                      staggered joint did a great job of giving a "fair curve" bend to the
                      sweep of the bottom, credit to PB&F for this design nuance.
                    • David
                      Thinking about the original question I see two issues which need to be addressed: a) checking of the original floor b) strengthening the floor in case of
                      Message 10 of 29 , Oct 20, 2011
                        Thinking about the original question I see two issues which need to be addressed:

                        a) checking of the original floor
                        b) strengthening the floor in case of impact

                        a) Most of us would agree that fiberglass cloth in epoxy over a well sanded bottom will deal with the checking as effectively as any other solution. In fact just epoxy probably would, but the fibreglass cloth is relatively inexpensive and worth it for the strengthening anyway.
                        This can be done with the boat on its side one side at a time with a little care.

                        b) I think that with a little analysis the critical floor areas could be identified and reinforced from the inside rather than by sheathing the outside. This would give you the possibility of screwing/nailing into the smaller reinforcement panels from the critical areas of the floor rather than attempting the whole re sheath in one go. You can almost certainly screw the center panel into the keel from above


                        This adds weight low down but does not affect the bottom profile in any way. I can't find plans to the Navigator and, with interiors being up to the owner, actual distribution/access may be more complicated than in theory. I assume you really only need to reinforce the floor of the watertight areas.

                        David

                        --- In bolger@yahoogroups.com, BruceHallman <hallman@...> wrote:
                        >
                        > On Wed, Oct 19, 2011 at 8:16 PM, David <dir_cobb@...> wrote:
                        > >
                        > >
                        > >
                        > > My experience is that even small laminations are not as easy as they look. I managed to get voids gluing a rudder lamination. I hate to think of a full bottom. Weights were no good and screws make lots of holes. It seems much glue is called for.
                        >
                        >
                        > I agree that the clamping of a laminate is very tricky. I was
                        > surprised and pleased that the lamination process of the bottom of the
                        > Topaz Spyder went very smoothly. (Vacuum bag might also work fine
                        > too.)
                        >
                        > Here is how I did it with Topaz Spyder: The overall hull bottom is 1
                        > inch thick, made up of two layers of 1/2" plywood. Averaging about
                        > 6-7 feet wide by 31 feet overall long. The top and bottom layers were
                        > staggered by two feet so the joints were staggered.
                        >
                        > 1) I positioned the bottom layer on the strong back.
                        > 2) Then I made a batch of about 1 quart of epoxy, and poured it on 2
                        > feet of the lower plywood and on 2 feet of the top piece, then spread
                        > it around with an 10 inch metal 'drywall taping blade.
                        > 3) I then flipped the top piece and mated the wet glue face to face.
                        > 4) Taking two hammers, a carpenters hammer in my right hand, and a 3
                        > pound maul in my left hand (held underneath as a 'backer' to keep the
                        > wood from bouncing), I nailed the two pieces together using 7/8" #14
                        > silicon bronze ring shank nails at about 10 inch centers.
                        >
                        > I am confident that there were zero voids, as the ring shanks cinched
                        > up real tight. The silicon bronze has the advantage that it is just
                        > soft enough that you could then follow up with a pass over using a
                        > belt sander without eating up the belts, to get things smoothed up for
                        > the surface fiberglass lamination that follows.
                        >
                        > For this reason, I am worried about laminating two sheets of 1/4"
                        > plywood, as it it too thin to accept ring shank nails. Two sheets of
                        > 1/2" work fine, great even. It was surprising to see how the 2ft
                        > staggered joint did a great job of giving a "fair curve" bend to the
                        > sweep of the bottom, credit to PB&F for this design nuance.
                        >
                      • sirdarnell
                        Sand to wood. Coat the new and old bottom, where they are to be glued together, with un-thicken (and not thinned) epoxy. Allow to dry until both are tacky,
                        Message 11 of 29 , Oct 21, 2011
                          Sand to wood. Coat the new and old bottom, where they are to be glued together, with un-thicken (and not thinned) epoxy. Allow to dry until both are tacky, if any areas appear to have absorbed all of the epoxy, recover both pieces to be glued without sanding. Put on thicken epoxy on surface of first coated piece as it will be drier. Use a toothed applicator like is used with tile mastic for applying thicken epoxy. Now place new bottom on. Clamp as well as you can, using any or several of the suggestions, others have given. Do not clamp too hard, you do not want to squeeze out all of the epoxy. Since both boards are protected by the un-thicken epoxy any small voids shouldn't cause rot any problems.


                          --- In bolger@yahoogroups.com, "Kendall" <ken_j_@...> wrote:
                          >
                          > I just picked up my micro navigator over the weekend. The bottom of the boat is built to plans at 1/4" plywood and it has been patched a couple of times and is checking in places. I was wanting to get the bottom to 12" minimum or possibly 3/4" or 1" anyway. Can I epoxy some new plywood directly to the existing and then glass over that or should I remove what's there and start from scratch? The bottom is solid with out any soft spots and once I get all the paint removed I will do an inspection and replace any questionable sections if found. My reason for doubling the bottom is that I sail in a water reservoir and the level is constantly changing. It's a man made and there are lots of submerged trees that can get to just below the surface during low water periods.
                          >
                        • MylesJ. Swift
                          The ring shank nails don t seem to get much love anymore. They are cheap enough, apply good pressure in areas you can t get a clamp on. They work well for
                          Message 12 of 29 , Oct 21, 2011

                            The ring shank nails don’t seem to get much love anymore. They are cheap enough, apply good pressure in areas you can’t get a clamp on. They work well for people like me that don’t have a big clamp collection. As Bruce says they are easy to sand over without wiping out the paper. Plus you can keep working instead of having to wait to for fillets to harden.

                             

                            MylesJ

                          • Kendall
                            I m weighing the pros and cons of the suggested methods. I ll post my decision and results when I have them. Thanks for all the suggestions this group is an
                            Message 13 of 29 , Oct 23, 2011
                              I'm weighing the pros and cons of the suggested methods. I'll post my decision and results when I have them. Thanks for all the suggestions this group is an amazing resource. My immediate task is to get the Lexan windows installed and a sliding roof hatch built so that the interior will be in the dry. I'm tired of tarping and un-tarping the boat when I want to work on it.

                              --- In bolger@yahoogroups.com, "MylesJ. Swift" <mswift@...> wrote:
                              >
                              > The ring shank nails don't seem to get much love anymore. They are cheap
                              > enough, apply good pressure in areas you can't get a clamp on. They work
                              > well for people like me that don't have a big clamp collection. As Bruce
                              > says they are easy to sand over without wiping out the paper. Plus you can
                              > keep working instead of having to wait to for fillets to harden.
                              >
                              >
                              >
                              > MylesJ
                              >
                            Your message has been successfully submitted and would be delivered to recipients shortly.