inside edges.[open a door halfway and look at the gap between the inside of the door and the frame thats what your trying to get rid of] take your time here you'll save yoursef work in the long run. i suggset doing a dry run with just a few stiches to see where you might need more beveling

Thanks Greg.  Great idea about the dry run.  And taking my time.  Much appreciated!

Hello Alec-

I'm just starting a Shearwater 16.  Do you think the bevelling diagram is correct where the front deck meets the cockpit rim?  Is it really a 30 degree bevel meeting (mating) up with a 90 degree on the back deck piece?

helen in Iowa

Most important about bevelling is not to make 2 rights or lefts. Mark the insides of your panels and make sure that you are bevelling the correct side.

The angle isn't really that critical, it is going to be filled with a fillet. Just plane off the top 2 plys, at an angle a little greater than 45 degrees. With a sharp plane, I can do a whole boat in about an hour.

The bevel on the cockpit rim is there to let the epoxy into the joint. It is pretty much a butt joint with the bevel allowwing the epoxy into the joint after it is wired up. 30 degrees is plenty.

You guys are in the really fidly steps. You will be supprised how fast things go once you have tacked everything together and pulled the wires.

good luck JRC

Alec- you probably know this by now, but for any future readers:

Alec wrote:  The idea is to shave off the inner corners, so that the outer corners of the two abutting planks of plywood can more-or-less meet, and there is less of a visible gap on the exterior of the hull/deck between the planks. Also, the butt-ends of the plank would face each other better, and not just meet on the point of the corners.

Well, after stitching up the hull, I can say my idea about bevelling, which was the same as yours, was wrong.  The bevel does not create a butt joint with the 3 layer ply meeting 3 ply across the joint.  The ends of each plank do just meet on the outer corner points, maybe just one plywood layer.  The bevels actually -open- the joint on the inside to hold a wedge of epoxy in the joint. Folks claim the epoxy joint is stronger than wood.

helen in Iowa

The epoxy is way stronger, and heavier. Some of us have accidently tested out scarf joints to distruction. Even a bad scarf joint will break outside the joint. If you want a real demonstration, let a blob of thickened epoxy cure for a few weeks on some concrete, then hit it really hard with a hammer and see what breaks first.

Thanks, everyone.

Helen, now you have me a bit worried.  I beveled so well that the pieces fit like hand in glove.  Should I take all the stitches out and bevel more so there will be a wedge of epoxy?  Or will the outer shell of fiberglass and epoxy be enough to keep my Shearwater together? I had thought that was the point.

Thanks!

Alec

If you are happy with the fit, don't take it all apart. You might brush the joints with unthickened epoxy, to let it soak in a bit. My favorite tool for tack-welding is a condiment squirter. For tacking, make your epoxy about as thick as mustard. Just make sure to let them set up for at least 24 hour.

JRC

Thanks, JRC.  I like the idea of letting some epoxy soak in the joints.  You also responded to my question about CA glue; maybe I will use some dots of CA where needed (most of the joints really do fit well and stay beautifully in place from the beveling), then brush the joints with unthickened epoxy, then fillet.  Sound right?

Thanks again.

Not sure all CLC employees agree with this technique, but I did find this on their shop tips page: 
http://www.clcboats.com/shoptips/stitch_glue/round_edges.html

(of course this would not apply to joining any panels with lap joints but it worked great for me on the non lap joint panels)

Right, the unthickened epoxy will wick into the joint, then the thickened epoxy will fill the gap. Bot will set up and provide a nice solid joint. I like to use the ketchup bottle to tack with, so that I can simply fillet over the top of the tacks with little to no sanding. I can also get a full batch of epoxy in one go, instead of having to refill.

The bevel provides the same advantage of rounding. It also shaves a little more, so you have less of a gap on the outside to fill/sand later. I like planing a bevel a whole lot more than sanding.

Sounds like you are making good progress. Don't forget to check for squareness before you tack it up.

JRC