JEM Watercraft

Ho jcubero,

Walnut breat hooks would be lovely.

Mate If you do hand cut dovetails and mortise & tennon joints as a matter of course, You won't be having any trouble with a simple epoxy butt joint. Even I can do it

My work is not all that fancy because I'm still learning to work ply. When I finish my current project, I think I'll have a go at a pirogue and try to incorporate some flash timberwork into her.

Mate, I am really looking forward to some more piccies of your work.

Don't get too excited, I don't want to disappoint you! This is a first boat (yeah, I guess I'm tacitly acknowledging there'll be more) so I'm going to (mostly) keep it simple.

Javier,

There will be more - count on it. Once the bug of wooden boats bites you ....

As promised, the epoxy arrived today. (You've got to get this smiley for the forum BTW).


So with all the encouragement, I decided "no guts, no glory." Never mind the test piece, let's get it on! Finished cutting the bottom pieces, then clamped everything together for edge sanding. I have a block plane, so I used it to good effect to get everything close before sanding. Apparently, I need to work on making straight edges with a jigsaw. Ahem. Lesson learned: I used a very fine blade to reduce splintering, but it also doesn't track well - harder to get a straight line. There's a balance point there somewhere.


Alex helped again. First time he's used a plane, but he took right to it!



Then my wife (Kym) volunteered to do all the face sanding. 150 grit with a ROS (random orbit sander). Awesome, I *hate* sanding.
Since she's the Official Photographer for this build, here's her hand, LOL!


I went inside and read up on the next steps. When I came back out she was all done.
Then it was time for the epoxy. I laid down saran wrap on garage floor and got all the canoe pieces close to where they belonged. Here's me measuring:


Then I mixed my first batch of epoxy. I wet all the edges with epoxy, then added the wood flour until I got it to ketchup consistency, just like the directions. So far, so good. I then began applying the filler and putting the pieces together, using the string method to find the offset. The Merrimac has six pieces total - 3 each side. The first 3 went great, then it started getting tricky.
Apparently, when you live on the surface of the sun, AKA Florida, even the slow hardener is too fast. I was less than fifteen minutes into this and the pot started heating up in my hand, and the center of the epoxy started hardening up. AAAAAGGHH!
Quick, how fast can we do the last three pieces!!! Well, it seems we were *just* quick enough. Here's the result:


I also mixed up more epoxy than I actually needed. I'll have to work on that. For anyone else building one of these, the epoxy fillets are really not very wide, so not much epoxy is needed, and the wood flour adds volume. For me, about 60 ml of epoxy + 30 hardener should have been enough. I used 100 and 50. (Got the graduated measuring cups from RAKA.

Finally, I decided to do a little prep for the stitching. I did two things: I built a jig for even spacing of stitch holes. I'll probably show it later, but I followed the direction on this site, placing two holes - at 6 and 8 inches. This way, I can use 6 inch spacing around tight curves and 8" spacing elsewhere. Then I decided to do the "drill a hole in the kraft sticks" for spacers between seams. Since I have a drill press and little patience, I made a VERY simple fixture for drilling a bunch at a time. Just place a wood block as a fence behind the drill bit, spaced so you drill through the center of the sticks, then stack a bunch against the fence:


And in about one minute I was able to make a whole bunch of spacers. The one in the front shows it complete with zip tie:


So, tomorrow I can begin the next step. I should lightly sand the seams so they're flush, then I can apply fiberglass.
1st question: I have fiberglass tape 3" wide. Is it acceptable to use several strips of tape side by side *across* the seam, or do I need to use a single piece of fiberglass cloth to cover the whole area?
(sorry for dots, but the forum compresses spaces so it doesn't look right):
-------------------------------------------------------- board
\ ...................................| <- seam................ /
.\ .....................=========== tape.........../
..\.....................============ tape......./
...\.................................|........................./
....-----------------------------------------------
2nd question: If I have any voids, do I need to mix some epoxy with wood flour to fill them, or just fill with epoxy and apply cloth?
3rd question: Can I start in the morning, or do I have to wait longer for the epoxy to harden sufficiently? Please don't make me wait!

jcubero wrote:
1st question: I have fiberglass tape 3" wide. Is it acceptable to use several strips of tape side by side *across* the seam, or do I need to use a single piece of fiberglass cloth to cover the whole area?
(sorry for dots, but the forum compresses spaces so it doesn't look right):
-------------------------------------------------------- board
\ ...................................| <- seam................ /
.\ .....................=========== tape.........../
..\.....................============ tape......./
...\.................................|........................./
....-----------------------------------------------

You can use several strips or a solid peice of cloth. If using strips, some overlap is needed.

2nd question: If I have any voids, do I need to mix some epoxy with wood flour to fill them, or just fill with epoxy and apply cloth?

For any void larger than a pencil tip, use wood flour.

3rd question: Can I start in the morning, or do I have to wait longer for the epoxy to harden sufficiently? Please don't make me wait!

Stat with doing what? Stitching? Then yes, you have to wait.

Javier,
if you haven't done so already, you might want to drill another hole in the craft sticks to make the opening larger/longer. The ties have to go both thru the craft stick and back again (thru the exterior lower hull panel, thru the craft stick on the interior, thru the interior of the upper hull panel, and back thru the craft stick to the fastening part of the tie). Does that make sense?

Actually, now that I think of it, I drilled three overlapping holes in the craft sticks.

It's very difficult to hold back on the excitement and be patient once you start building! It's very addictive!

Stat with doing what? Stitching? Then yes, you have to wait.

No, not stitching, just applying the fiberglass tape to the seams, front and back. I figure by morning the epoxy will be dry enough to tape. I'm guessing I have to do all the fronts, let that set overnight, then do the backs?

scotrunnr,

Why do the ties have to go back through the stick? I was figuring I'd just put the spacer through one leg of the tie. They might not be perfectly square, but then they don't have to be.

Why do the ties have to go back through the stick? I was figuring I'd just put the spacer through one leg of the tie. They might not be perfectly square, but then they don't have to be.

Very good question mate.

I think the answer is that by keeping the spacers pretty square, it alows more room to tack the panels together.

For my spacers, I ripped some 19mm pine down into 2mm thick strips then cut a slot in the middle about 30mm long with a mortising chisel. Could be done easily by drilling two 8mm holes at about 25mm centres and chopping the centre piece out with a wood chisel.

Hope this helps a bit mate.