> Anybody want to critique my thinking, or comment on other merits of the
> two joints?

Simply put it just doesn't make a whole lot of difference in what kind of joint you use.

Consider three common construction items: Bricks, plywood and laminated structural beams.

Plywood is made up of layers of wood veneer that meet with butt joints, and then are covered with more more layers of veneer--which overlap the joints of previous layers. Laminated beams are made up from shorter lengths which are glued together. Each piece joins the next with a simple butt joint, but those butt joints are surrounded by solid material from adjacent pieces.

The effect is very much like how bricks (surrounded by mortar) are stacked in a staggered pattern to build a wall. The individual butt joint between two bricks joined end to end is pretty weak. Yet the accumulation of many of these joints adds up to a wall that might last a hundred years or more.

Now lets look at boat construction. With simple plywood panels that are scarphed together you are basically creating a longer plywood panel where the joints between individual layers of veneer are offset by anywhere from 1/4 inch to an inch. Use good glue or epoxy and this could hold all by itself.

If you cover this joint with a layer of fiberglass cloth on both sides you are effectively making your own plywood -- and the joint here is going to be as strong or stronger than a butt joint between layers of plain wood veneer.

If you don't use glass cloth, you can use a piece of scrap wood behind the butt joint to reinforce it. It may not flex as smoothly as a thin, even piece of plywood, but it will certainly be strong enough.

It is not just the type of a single joint, but the combination of all the joints and all the pieces of wood that go into your boat which combine to contribute to the strength and structure of the craft. Don't get hung up on a single element. Think of the whole.

hope this helps

Paul G. Jacobson