Mortising for outer stems

[doe4rae]

A few questions before I get too far into planking the hull. I put two strips on today so I have some time to work this out in my head still but I have a lot of confusion about how the strips are supposed to "land" at the inner stem in order to not create a problem for the outer stem. I've been looking at Glen's pictures a lot and reading the posts. I have a question about one picture in particular (Glens) and I'll try to set the link here.

This picture seems to show that the planks are cut flush with the 1/8" leading edge on the outer stem and then as it curves to the bottom of the hull, it looks like the planks are being cut to create a "V" that receives the Outer stem. I visualized it in my mind from reading CanoeCraft, that I would simply cut every set of planks on either side completely flush to that 1/8" inner stem edge and then the outer stems that I steamed and laminated at the same time as the inner stems would lay flat on top of the 1/8" inner stem PLUS the width of the 1/4"planks (about a 3/4" total width to cover with outer stem). Is the problem that others have posted here, having to do with the fact that at some point while planking they are covering the inner stem with planks? Maybe I just haven't read enough to get a handle on how this works out (when the planks stop being trimmed leaving inner stem exposed and when they start to cover the inner stem and butt up against one another from the opposing sides. I'm probably really complicating this but I don't want to go too far and realize I needed to do something different and since I don't really understand what the other guys did that was a mistake I'm sure I'll make the same one. In Glen's picture (see link) it seems like the outer stem has to be shaped to a "V" on the side contacting the inner stem. Maybe I"m just not seeing the dimension properly from the photograph? A lot of my confusion here stems (pun intended) from my lack of familiarity with what a 'mortise' is. I thought I could figure it out from the pictures and I have a general idea.. but still not getting it. I want to cut all my planks off flush with the inner stem and I'm getting the gist that this is wrong.

http://woodcanoes.multiply.com/photos/a ... ms#photo=3

[Patricks Dad]

The outer stem indeed rests on top of the inner stem (from one end to the other). As the inner stem curves toward the bottom of the canoe, the planks will migrate from crossing the innerstem at a 90 degree angle to ~0 degree angle. The outer stem will cover the butt end of the strips near the sheer (the strips are indeed cut flush with the inner stem there). The mortise is not shaped like a "V" it's more like a "U" (with square bottom corners). The mortise starts at zero depth and reaches a maximum depth at the end closest to the bottom of the canoe. The width of the "U" gets narrower as it approaches the center of the canoe.

It's really harder to describe than it is to do.

[Glen Smith]

The photos at this link by Ealger are pretty self-explanatory in my opinion. This is what I considered the most daunting step during my first canoe build. I had to screw-up on the first boat before understanding how to do it correctly. I didn't have internet back then, just books!

http://s12.photobucket.com/albums/a237/ealger/Ranger15/

[mtpocket]

A mortice is a groove in one piece that another piece fits into. On the nose of the canoe the strips glue to the inner stem along the sides. As you reach the point where the bottom of the hull is being stripped, the strips are glued more on the face of the inner stem than the sides. This is the only area that requires a mortice. The reason for this is that the nose of the canoe is the same width as the outer stem. The area near the bottom where the strips meet the inner stem is wider than the outer stem. The mortice/groove is the amount of wood you have to remove to get back down to the level of the inner stem. In the case of using 1/4" strips, the mortice will be 1/4" deep. The width depends on the width of your stems. Most builders use 3/4" wide stems. The trick is to chisel out the mortice 1/4" deep and 3/4" wide without making the mistake of digging too deep. A mortice that is too deep is one that reaches the inner face of the strips. In other words, a window. Not good! Chisel to the depth of the inner stem but no further. It is important to keep the mortice the same width all along. I've read where some builders have made "V" shaped mortices. My personal belief is that it works just as well but is more difficult to get a tight mortice.

Another way to describe a mortice is the slot that a dado blade makes.


You're doing the right thing, asking questions and reading about things that don't make sense before you make mistakes.

[Patricks Dad]

It is important to keep the mortice the same width all along.

I think Canoecraft recommends that the outer stem (width) and it's associated mortise (width) be tapered (narrower toward the last station mold e.g., station 6). I have done it both ways (tapered and full 3/4" wide). Either can work but don't let this description confuse you (It did me when I first read it). The key is cutting your mortise to match the stem.

[Patricks Dad]

One more comment Dawne. If you look at picture #2 in the same set of Glen's pictures where you referenced #3, the picture and it's associated description has a good description of the mortise and the tapering of the stem.

http://woodcanoes.multiply.com/photos/a ... ms#photo=2

[doe4rae]

I really appreciate all the extra advise here... I was hesitant to ask that this topic be revisited again -- it seems to be a popular one.
I have a much better concept of how this is supposed to evolve as stripping progresses along the stems... thank you very much for your GREAT support!