JEM Watercraft

Aesthetics being a personal thing, it seems to me that changing up the position of the butt joints on the 16' panels of plywood used for stitch and glue canoes would be a good thing--creating offsets rather than a line in the middle of the boat--similar to what I see in a hardwood floor.

In a 5-panel boat, such as the Iroquois (recently ordered--waiting for the post-Christmas shipping...) I'm going to be attempting, it also seems that I could create this offset effect by just changing the position of the joint in two of the panels and leaving it in three (the top side panels and the floor panel).

This would be accomplished by taking two of the 8 foot pieces and cutting them in half, using the outside squared edges to join with an 8 foot panel. Thus, a 16 foot panel with two butt joints, but now offset from the 3 panels with the middle butt joints. Any thoughts about how this would affect the integrity of the hull? I'm planning on glassing both inside and outside.

Also, if glassing inside and out, is it necessary to have a backing board on the butt joint--regardless of position (middle or offset)? Would position affect the need for a backing board?

G'day JT,

Some very good questions there mate.

While I haven't built an iroquois, and haven't attempted the panel offsets you mention, I will attempt to answer your questions - if I may.

I have often thought about off-setting the panel splices in the hope of achieving additional strength in the build. There are several reasons why I haven't bothered to make the attempt.

1. The fibreglas panel splices, when combined with the adjoining other hull panels are very strong as they are. They support each other and their combined strength is much greater that the sum of them individually.

2. It requires much more work to offset the panels. If I understand the Iroquois, It is a symmetrical hull, in that the back panels are identical to the front ones. If this is so, then, each panel will have to be measured and marked individually. This creates more room for builder error.

3. If the joints were well done, it shouldn't have any adverse effect on hull integrety but the problem lies in doing them well. There will be QA sheets in your plans. All the ones I have seen, have their measurements specifically related to a given point on the end of your panel and the butt joint in the middle. This could also be problematic.

Butt Blocks, as I understand them, are an alternative to the fibreglass panel splices. With offset panel joints, you would have ply but blocks scattered pretty much all over the inside of your boat. I don't think this would be very pleasing to the eye.

Mate, with respect, regardless of what woodworking skill/experience you may have, if this is your first S&G build, I would encourage you to build as per Matt's plans and build instructions. The hull is well proven, just as she is and be sure, there is a learning curve involved in the process.

I teach woorkworking as part of my job, and with my first build, I still made a lot of basic and funadmental mistakes. The worst of which was not sticking to the plans or build instructions. Once I deviated from them, the problems just increased. A mistake led to more mistakes in trying to correct the original and so on and on.

Good luck with the build mate, and please share with us your adventures. We will help out where-ever we can.

The joints can be repositioned without compromising strength on this design.

You need to use a wooden splice or fiberglass splice method to create the long panels. Then glass over either one.

You might want to make the full length panels as per the drawings from cheap plywood. Join them using wooden butt block or fiberglass splice. It'll be good practice.

Then use the full length panels as a guide to where you'd like to reposition the seams. Trace onto the ply you'll build with. You might end up needing more plywood than the plans call for.

It might be a bit complicated if it's your first boat. But it certainly can be done if you're very careful and patient.

Thanks.

I guess another aspect of my question, then, is whether or not I will paint or show the wood. I'm assuming that the line of the butt joint, once fiberglassed, won't show under paint, making the placement of the line irrelevant regarding looks--assuming the joint is well-done. Is that correct--after fiberglassing, will the paint cover the butt joints smoothly?

I sure like the look of the red Merrimac on Matt's website...

The paint should cover things up nicely.

JT, I was going to remain silent until you mentioned covering the wood with paint. You can do that, but it's like putting a burlap bag over beautiful woman. A sad waste.

Just my opinion. (But in this case - it's very true.)

Haven't decided yet 'bout painting. Right now I'm still in the "virtual" phase--all the anticipation and ideas from visiting the forum (which means that I have not yet read the full instructions--and probably should wait on some of these questions that are probably answered in the plans...).

I'd like to leave the burlap off, so to speak, but am not sure about what the quality of plywood will end up being, most likely luann from lowe's or HD. While I'm handy around the house, most projects have been painting or tile work (BTW--thanks to another great forum--John Bridge @ Tile Your World), not finishing wood. That being said, I'd like to create a dark, mahogany look to the outside of the hull, with the gunwhale a bit lighter--which leads to the next question:

If I do the wood look, but need to apply a stain, when does that step happen? Wouldn't it be prior to the butt joint, so as to be under the fiberglass/epoxy used in the joint?

Apply water-based stain right before you apply fiberglass.

jt wrote:If I do the wood look, but need to apply a stain, when does that step happen? Wouldn't it be prior to the butt joint, so as to be under the fiberglass/epoxy used in the joint?

JT;
I have no experience with staining a boat, but my thought would be that the stain would need to be applied before ANY epoxy work happens. I would say cut your panels, then stain, then start assembly. My reasoning is that any wood with epoxy on it wont take stain. A smearing butt joint, a smudge of epoxy on a panel, or even a small run in the epoxy would give you a area that will not take stain. Resulting in a spot or stripe (or a free form geometric shape) of lighter colored wood.

Just my two cents.

DM

Yes good point DM.

I was skipping over that part in my pea-brain.