Want to replace aluminum gunwales with wood

I've been meaning to build a cedar strip canoe for years and will. In the meantime I have an older glass canoe with aluminum gunwales I use for therapy. The gunwales are not a flowing arc but instead have 4 distinct bends in the lines of which one has been bumped and misshaped. I'm going to replace the aluminum gunwales with walnut ones. I'd prefer to go back with a smooth flowing arc on the gunwales but wonder if that will affect the hull of the canoe. It would be no problem to bend the gunwale to the original shape though. Anyone have any ideas? The existing bends are at the thwarts.


ive also been looking at ideas for doing this and there's not much on the net. I'm assuming it'll be cut strips to size, scarf, cut a dado for the glass, route to shape, screw inner and outer gunwales on to the hull, fit new decks and finish. I'm i missing anything other than seats and thwarts?

Thanks

Not sure I fully understand the "dado for the glass" part but this job should be fairly straight forward. Scarf the joints before hand and install full length. Easier to get a fair curve that way. Use at least a 7:1 scarf. If you choose to reduce the width fore and aft, start about 3' from the end and plane the inside or faying surface to the taper needed. This will allow the outer mold line to be fair. Be sure the faying surfaces are sealed to reduce the chance of rot. You may also want to consider something lighter in weight for this application.

Well Jim, I'm thinking I want the top of the fiberglass hull covered for both protection and aesthetic reasons so I assumed that a dado on the edge of the inwale would be the way to do it. Is there another way? This is why I was asking.

as far as wood goes, walnut is a lighter weight wood than the common gunwale group of ash, oak and maple. I also happen to have an abundance of it in 9' lengths so it's my choice. considering the amount of wood used on gunwales would species of wood make more than a few ounces difference?

Thanks, mark

OK! Now I understand the dado part. As for other options the only thing I can think of would be an inwale and outwale with a cap rail. Probably a lot of work to get it right. As for the walnut..if you got it, use it! I'm just not accustomed to seeing it used in this application. I always used ash as I had a pretty good supply at the time.
Post some pics!

thanks again Jim, I thought about a cap also but decided it would have to be flush mount or a lot of trouble so I X'd that idea. I'm hoping my glass is uniformly thick so the rail will join evenly. If not I'll have to oversize the groove and slip in spacers at the screws.

it's not a great canoe. I bought it at sears in the early 80's. I don't want to put a lot of time or money into it. I really need to start that cedar strip.

Mark - that approach can be done and actually is on some glass sailboats that have wood rails (look at any modern Thistle). But it is a somewhat more complex approach than just sandwiching the glass and sanding the top smooth. I'm not sure you will actually see any benefit. In fact, since the construction is more complicated I could almost assure you the end solution is not as good (and certainly not as light) as an inwale and outwale clamped with thickened epoxy as the adhesive and screwed, bolted or (my preference) riveted.

Either way, lots of clamps and a few extra hands are helpful to make assembly easy. The inwale tends to be more difficult to set because the length is somewhat tricky to get right. Use tape and protection below the joint to keep the hull clean of adhesive, and remove the tape before the epoxy is fully cured.

Happened across the attached photo of adding new rails (white oak inwhale/outwale) to an old fiberglass hull. Note the sandwiched glass hull sanded smooth on the top. Might be similar to your intended solution.

I'm with Bill. The idea that a dado will protect the fiberglass edge is mostly an illusion unless you bond it in place with epoxy to completely fill the dado. And that's really fairly improbable, not to mention expensive. If you sandwich the glass between the inwale and outwale, you can then fill the exposed glass edge with (thickened) epoxy and get a very good seal that will actually work better than your dado can hope to do.

Bill, thanks! The idea of just leaving the glass exposed never crossed my mind. It doesn't look bad so I may try it when I start.

James, it wasn't about protection. It was simply what I told bill, it never crossed my mind.

im not going to start until it gets cold out which here in tx may be dec, jan, or never. When I do I'm going to cut test pieces and try both, thanks. I'll post results.

btw ... if you want to make the rails so narrow (think light) that they might not hold screws, consider using rivets. I get mine from Faering Design but versions are available from most boat suppliers (ie. Jamestown) in a wide range of gauge and length. Inwale and outwale can be installed using rivets either with or without glue and with minimal (primitive) tools. I use a sledge hammer hung around my neck with a rope (for ideal vertical positioning) as the anvil. The photo above shows post glue-up installation. You'll need to test whether you can drive the rivet through the pilot hole in the fiberglass. The look is very nautical and having many boats this way I can assure you the strength is superb.

Lastly, while I'm sure Walnut would work, White Oak is traditional from a durability and flexibility perspective. Pst photos when done!