laminating gunwales?

[purple otter]

has anybody laminated gunwales on a curved form instead of using a scarf joint?it seems to me that you could use 1/4" strips ,like the stem,and stagger the joints.I had 3 scarf joints snap ,i didn't think i starved the joint but now i am gunshy to try again. thanks for any advice!

[Tim Eastman]

Actually a scarf joint is a pretty darn strong joint if your cut angle is 8 to 1 and your epoxy is properly thickened. We did ours and used UN thickened epoxy to soak into the joint first and then swabbed some thickened epoxy in the joint. Clamped it good and straight and true and we've been paddling her for over a year now.

And yes I was worried about blowing the joint. But you never get experience until after you need it.

[purple otter]

thanks Tim.maybe i will give the scarf one more try.are spring clamps or tape enough to clamp without starving the joint?how about a biscuit in the joint? Thanks again for the advice!

[Glen Smith]

As Tim said, apply straight epoxy to the joints until they no longer absorb any more. Then wipe off excess epoxy before applying the thickened epoxy. Using West System "microfibers" makes a very strong joint. Use an 8 to 1 ratio for cutting the scarf joints and try to make them in a portion that won't require much bending. A light clamping pressure is all that is required. I usually fasten a few pieces of wood to a piece of plywood, cover the area where the joint will be with clear plastic packaging tape, glue the joint, install between the pieces of wood and use clamps to hold the gunwale down to the plywood surface then a few small wedges between the gunwale and one of the pieces of wood just to get a bit of squeeze-out. Too much pressure will creat a dry joint. Make alignment marks on the gunwale pieces before gluing them and rely on these marks to align them on the glue-up table. Allow to setup 24 hours before moving the gunwales. Clean up the squeeze-out and you are ready to go.

[jfranck]

I used some mahogany from an old coffee table so had to use 4 pieces for each gunwale. I scarfed them at 5:1 and only had one joint fail so far. I think that was because I tried to do too many joints from one batch of epoxy. It doesn't work to use epoxy that has already started to cure.

I have a web page with some of the mistakes I made. If I make a second one, it should be alot easier.

My web page is http://mysite.verizon.net/jimfranck/id10.html

[purple otter]

I found long lumber!!!A local mill has Brazilian walnut 1"x1 3/4"x20' for $10. Just enough fora set of outwales.It is a beautiful match to the black walnut i used for the deck ,seats and inwales. :big grin

[Woodchuck]

Gunnals are compound bends because they curve both horizontally and vertically and that's the reason why laminating doesn't really work. Laminated pieces only bend perpendicular to the flat side of the boards laminated. IMHO With a scarf joint, you want to put the scarf near the center of the canoe so it does not have to bend up or down in that location.
CYA, Joe

[AlanWS]

I've read descriptions of laminated gunwales, but the reason it was done was for light weight: a thin strip of hardwood provided wear resistance on the outside of gunwales mostly of spruce. If you have a sharp compound bend, it certainly could complicate things. My approach is to avoid such designs. You could get a rather unusual look by running laminations horizontally, I suppose.

I have found that a scarf joint works well. I think I used about 7:1. To clamp, I put waxed paper around the join, lined it up, and put a piece of strip on each side of the join, spring clamped on each end to hold the joint in proper alignment. With those clamps in place first, I then added a spring clamp on the join itself. The reason for this order of clamping is that pressure on the joint will tend to cause it to slide, messing up the alignment. Clamping to the scraps first prevents that. The other things people have mentioned, about letting unthickened epoxy soak in as much as possible before adding epoxy thickened with microfibers, is also important for a strong join.