need help in building a small catamaran

ok guys, thanks. i was thinking about some way to build and i would like to hear your opinion. since this canoe has very few seams (2, between bottom board to side boards and 2 between side board in the front and in the back, bow and stern) i thought to build strongback (i think this is how its called) and instead of using stitches, to nail with temporary nails, the boards to the strongback and create the shape of the canoe. then to go over the seams with glass tape and epoxy. when it cures, there is a canoe shape that i could turn up side down, hold with temporary spreders in the right shape of the beam and applay the putty in the seams inside the canoe. do i need to put the putty on the outer seams before i put the glass tape and epoxy or it is enough just the tape and epoxy? i save like that the whole stitching thing. i have planty of scarp wood here that i could use to build a strongback and it could be used by others to build more canoes.
any comments on that?

 

hmmm....nails ? Nails have no place in modern plywood construcion. Review literature on the internet...you need zero nails...zero mechanical fastners. NONE. google Stitch and Glue...seek info on the internet.

 

temporary nails. just to hold the shape of the canoe while applaying the glass tape on the seams, and then take them out. not good?

i saw that i could use duct tape just to hold the boards in place and then turn the canoe up side down and applay putty in the inner seam. is it better?

i do read a lot now on the net and went to have a talk with a boat builder here in the marina but i guess i need to do the practical part too. hope to start soon

 

What do you nail too ??? How do you keep the thin flexible nature of plywood from deforming under the nail ? The idea behind Stitch and glue design is to use natural shapes for plywood use , NON COMPOUNDED CURVES... and gently GENTLY bring the ply panels together to form a FAIR...no bumps shape. Its entirly possible. The load, force gennerated by the stiching is very small when you build the correct shape. Build a model from superlight model plywood and superglue spot weld then you will see, i less than an hour buld time , before your eyes, what I mean..

 

i want to nail it to a strongback, i think this is how the male mold is called. i want to build some kind of frames (like a male mold) that on them i will put the boards and nail them to the mold just to keep them steady and nail only on the sides, not in the bow and stern.

 

Not normally...Normally nthe hull...floats on the strong back...so that all the corners and curves " pull" into shape as you gradually tension your stitchs.

Have a look at this...I havent watched it.... my internet connection is much too slow.... but the guys at this company are pretty good.

http://www.guillemot-kayaks.com/guillemot/blog/nick/stitch_and_glue_night_heron_class_video

 

ok, nice clip. thanks

 

From model to reality

Yoram, you will find "your" way to "your" boat. Here are photos of a model of mine (1m long) which was the test for my drawing. From this I have built the 4,20m Canoe to have a look for the hydrodynamics of a beamy hull with floats. But I didn`t finish it because of other (bigger) projects.

 

Great Boat !! and simply to build.

 

yes, looks good. i still have to build a first and easy to build canoe just to get the idea how things are done and then if i like the whole process, then maybe a boat of my liking. so far guys you have been of great help. i appreciate that.

 

Thats the way to go...build a simple craft...learn how to use the materials, have some fun on the water, then aattck something bigger , more sophistcated. Many, many cheap simple plywood boat plans availale...pic one up and get busy this weekend.


http://www.jemwatercraft.com/pontoon.php

 

any of you have some kind of experience, working with polyester (instead of epoxy)? whats are the disadvantages and advantages compare to epoxy? is it possible to make a putty out of polyester, hardener and sawdust?

 

another question, any of you came across trimaran with a retractable arms? so that the amas can be pull closer into the middle? i know about folding amas, above and below and to the sides of the middle but some kind of a device that would pull the side arms into the middle?

 

You could use polyester but its engineering properties are so poor compared to epoxy that you would be wasting your time and a pile off wood. With all the designs you will come across its best to FOLLOW THE BUILD METHOD AND SPECIFICATION TO THE LETTER.. The only way to build a cheap boat is with your cheap labour. don't substitute materials . Choose a simple design...and get to work. Retractable arms..everything is possible , but the more possibilities the more complex and expensive the build. Go ugly early and get out on the water NOW..the consider the possiblities while enjoying your simple first craft.

 

Folding floats

Retractable floats are possible without severe problems if the loads are low on the folding arms and the hinges. This canoe (lower picture) was successfully built and sailed in Canada.