Hey - you’re welcome!
Now for my next magic trick … for those who don’t want to spend the entire summer laying up three hulls via balsa strips …
Foam covered with glass !!! Taa Daa !
Use the same templates from above - but this time you are going to use the parts you normally would throw away. (The female or negative part of the template cut-out.)
These must be all cut so they end exactly at the half-hull line (vertical).
- Layout the side and top view on a piece of 2 inch thick pink/blue/gray house insulation foam. (Extruded kind - not the white expanded kind)
- Use bandsaw, hacksaw, framing saw, etc. and cut out the general side and top view.
- Mark off the location of the templates along what will be the outside of the half-hull.
- Glue up and cut out the same number of section templates as before - but save the “OUTSIDE” part of the cut, not the normal inside. (Actually save both)
- Number the sections and number the lines on the foam.
- If you want to be cool and quick, use a Dremel and sharpen the curved edge that represents the outside of the hull ON THE CUTOUT TEMPLATE. (female side)
- locate the proper station line on the foam and make sure you are using that template.
- Carefully - but firmly press down on the template, forcing the sharp edge down onto the foam. Pressing down “should” leave a cut line in the foam when you remove the female template outline. Don’t worry about crushed foam that may have been mashed instead of cut.
- Using a plane, belt sander with 80 grit paper, an electric hand plane, or even a “Sure-Form” type file begin removing the foam. Do this directly over the line that was pressed into the foam. It helps if you have an area of foam removed of about 3 inches wide directly over the template line you pressed into the foam.
- Keep removing foam and be careful You want to remove the foam ONLY down to where the line stops. This will leave you with a place at each template location that has a curve to match that of the female template.
- Once you have all template lines shaped down so it is almost impossible to see the line - use the same technique to remove the foam BETWEEN the section areas already shaped.
- Use your eye to blend in so there are no bumps between section lines, and no hollows at the section lines. A thin piece of flexible wood, about 1/2 meter long with sandpaper will help keep from sanding in hollows.
- When done, you should wind up with one half (vertical) of the main hull or float.
- Repeate 5 more times so you have both hull halfs and both float half hulls.
- Use a medium grade of sandpaper to gently shape and sand to remove any coarse sanding marks. Use about 100 grit - it doesn’t have to be really smooth - but you want to remove any hollows or high spots.
- Glue both halves (left and right) of the float together. You can use regular yellow wood glue. It will eventually be inside and protected from water.
- Once glued together, cover with a single layer of 1/2 or 3/4 oz. cloth. Just to prevent dents of the foam. You MUST USE EPOXY as polyester resin will melt the foam. Give a coat with enough resin to adhere and wet out the cloth. Don’t worry about cloth weave. After cure, give a second coat and try to only use enough to fill weave. Once this cures, you will need to fair any areas where you missed a hollow. Fair, sand, fair, sand and so forth.
- For the main hull, you may want to hollow out an area for radio gear and rudder linkage, etc, BEFORE gluing half-hulls together. Then simply finsh like th floats.
- Locate where cross beams will attach, and cut out or drill oversize holes. Fill holes with epoxy and you can imbed nut/bolt before cure. Just be sure to lubricate bolt (not nut) so you can remove it after epoxy cures. Basically you will have a solid epoxy plug with a nut at bottom and threaded center hole to match your connecting bolts that have been removed.
For main hull attachment, I suggest three bolts for each cross beam. For the floats, I would suggest at least two per attachment point. Obviously you can always glue the cross beams in place, but won’t be able to dismantle for travel!
Go to Jean Margail’s site for photos that will help explain this process. It’s a longer description than above strip method, but if you are all set up to go, you should be able to shape and cover a set of hulls in a weekend of steady work. Takes longer to explain than to do. I guess I could say …“Shape foam, cover with epoxy/glass cloth!” [:D]
http://water.resist.free.fr/Anglais/Construire.htm
Anyway, this really is an easy way to build, especially if you don’t have wood working tools, or a lot of time to strip build. Just remember the final size of 48" x 48" when done. After completion, I can email you a view of the rig/sail and a rudder and board outline as well.
I also want to note that this method (covering foam) will be heavier than strips, but I really don’t think you will notice much lack of performance. And, if you liked it and wnat a lighter boat, you can always use these hulls as a plug for a mold. Then layup a glass or carbon hull if you really need light weight.
With April 2005 (US) pricing, I am guessing you could easily build a set of trimaran hulls for about $100 US as follows:
<u>WEST Epoxy </u>
1 qt. resin, 1 Pt. slow hardener @ $60
<u>Foam</u>
1 sheet - 2 Inches thick x 4’ x 8’ @ $16
<u>Thin plywood </u>for templates @ $8
<u>Glass</u>
2 yards 3/4 oz. (50" wide) @ $10
<u>Miscellaneous</u>
sandpaper, stir sticks, gloves, etc. @ $10
Replace the foam with balsa wood if you want to strip build BUT add you will add a lot more time/labor to glue up all the strips.
I guess the queston is:
$100 for hull and 2 floats
$ 20 for 2 carbon crossbeam tubes
$150 for RMG winch
$100 for AM 2 channel radio, receiver and rudder servo
$200 for rig and professional paneled sails.
$ 50 for rudder and daggerboard
[:-thumbu] Thats just a bit over $600 and I would guess it would blow away any IOM, US1M, and probably most “M” Class boats which cost $1,000 - $1,700 (or more )!
<center>Go On - you know you want to try it! Give it a go!</center>