Plywood canoe

If you have fibreglassed all the outsides, this is a good time to put the sheer strake (around the sheer on the outside). It will force a fair hull shape, and stiffen up the hull. The temporary frames will ensure that the strake is at the right distance from the centreline.

The other advantage of putting this on now, is that you can use the frames as an accurate way of locating the height of the strake, by measuring up each side. Once the frames are gone, trying to measure the position is more difficult

I found that a series of laminated strips of wood were easy to apply, and looked attractive, thereby avoiding all the hassle of steam bending.

http://greencanoe.weebly.com/turning-over-a-new-canoe.html

 

I can see the sense in that, it would be stupid to lock in the wrong shape for the gunwales.

Gunwales seem the most problematic part of the boat. Some of the builds I have seen, seem to have spent more on clamps for the gunwales than on plywood.

When I started this project I thought how could I avoid all the problems with bending to shape and decided to cut them from plywood and laminate. However using 4mm ply it would take a lot of time to fit and now with the cold weather a lot of waiting time between each layer.

The motor canoe/Waterman design has a large bend in the sheer which I intend to reduce. The plan is to raise the midships level by 50mm to make it feel more like sitting in the boat rather than on it, be more suitable for rowing and increase freeboard for sailing. Also drop the ends by 90 to 100 mm. I tried clamping a 25mm x 19mm batten to the outside and it fitted without the need for steaming.

The idea is to clamp on a gunwale and adjust to the most pleasing shape, it may look a bit different as it will not be running parallel with the chines but this is true of most dinghies. I have left the pencil line grid on the top plank so can transfer the position to the rear half and other side of the boat to match up.

 

Gunwale stuff is EXPENSIVE. Get some regular molding and epoxy in place ....

 

I like your idea of fiberglass inserts to act as preinstalled bulkhead compartments .... watertight? Would you foam them as well for added flotation if they leaked?

 

I did put foam at one end of the canoe, but the increased weight on small craft is an issue.

Maybe they could have partial foam, say on the bottom - ro make flat storage inside.

The problems of post-fitting stuff is the bane of boat building.

 

Gunnels for a canoe are fairly simple.

My own preference is to add the inwales to the sheers while flat since the ply planks are floppy and the inwales stiffen them, they are much easier to do that way, although that will not work with scuppered wale's.

For your hull I suggest you install the breasthooks first which will provide additional support to the flexible sheer planks. Canoes often have decorative breasthooks - google it for ideas. Note the way they are shaped to accept the inwales later - this will depend on whether plain or scuppered inwales are desired.

The outwales are next; these may be rabbeted to hide the edge of the ply. Put both on dry (no glue) to check the fit and verify the clamping arrangement, also take the opportunity to verify the hull is not distorted. Then remove, glue and replace them one at at time; a trick I use for gluing is to unclamp an outwale between midships and one stem, glue and reclamp, then release the other end and repeat: it saves having to handle a long, slippery strip that just wants to spread glue all over the hull.

Scuppered inwales are a little more difficult than plain ones; they help drain the inside of the boat but in a canoe their biggest advantage is added stiffness at minimum weight. I prefer plain ones, and I bevel the bottom edge to assist drying out the boat. It is a bit complicated to describe how to fit them here but you should be able to find a tutorial or blog on the net.

 

I've never liked the faux inwale, clamp (what Terry calls a scuppered wale) assembly. It's a left over from the days of a clamp on the inside of the frame heads and not really the easiest way to do things.

On small craft what I prefer to do is employ a inwale, directly against the planking, tied to a rub rail on the outside. This still leaves a lip on the inside to prevent drainage when the hull is tipped, but you can leave them short at the ends a few inches and ditto the breast hook(s). This permits them to drain if tipped longitudinally. You can also bevel the underside on the inwale (as Terry suggests), so it'll shed water when tipped side to side.

 

Its easy to add an inwhale if the frames have been shaped to allow that, but otherwise, not.

Most light boats dont need an inner and outer strake, eg many kayaks rely just on the deck for the strength.

If you have just an outer strake you get protection of the hull on storage, land impact etc,

If you are worried about having to replace the outer strip after years of impact, you can have a separate non-glued extra strip around the outside, but usually its just easier to countersink any fasteners deeply, so you can plane or sand back to a firm surface prior to adding another strip to cover the damage down the track.

 

- good point! If an outwale is added first the sheers are stiff enough to allow the frames to be removed while an inwale is added.

- that’s quite true, however an inwale provides a handy grip when a lightweight canoe is being carried or lifted overhead for car-topping, and a thick outwale is more difficult to bend than a separate in/outwale - depending on the shape of the boat.


Has the outer stem or cutwater been added yet? There are several ways to blend it with the outwales, depending on the desired look. The easiest way is to taper the outwales to a thin edge together with the rub rail if used; a half-round hardwood molding finished with a fine taper looks well with this style. If this is done the stem is planed to blend into the sheer surface all the way to the top. Another way shown below is to leave the cutwater square at the top and bevel the inside ends of the outwales to blend in; getting the bevel and length both right can be tricky but not all that hard to do.

 

That is pretty!

Do the brass screws have a problem with separating over time? Or, did you use glue as you screwed them in?

Wayne

 

It is indeed pretty but not one of mine. I use brass screws sometimes but always in addition to glue. I use SS if I wanted to secure something that had to be removed, or bronze for sea use. Mostly I use brass screws to fill holes after using steel screws for "clamping" and to avoid filler on a bright-finished piece.

 

What do you mean when you say you use SS?

 

- stainless steel

 

THANKS!

Shoulda thought of that, but I woulda still needed clarification.

wayne

 

Thanks for the various inputs since my last post. With Christmas approaching I shall not be working on the boat for the next fortnight so will be thinking which methods will be most suitable.

AK, there is no outer stem or cutwater at the ends where the planks meet. The designer suggests using filled epoxy on the outside to get the curve then cover with tape and epoxy. I intend to fit an inner stem which might come above deck level.

Having got the ends of the planks together and the the ties out, at some stage I shall countersink the holes, drill through the inner stem to link the pair of holes, then fill with epoxy and fibres to create an epoxy rivet. The holes away from the bows I have already countersunk each side and epoxied.