: My question is really applicable to all S&G construction.

all or most s&g yaks align their seams. Even in the worst structural locations. so it must not be an issue. Have a look at the centrally located seams in the following:
http://www.pygmyboats.com/Construction.htm

and I presume the same thing is expected on the sheet of 2x18 ply you made up before laying out the plans.

So structurally, doesn’t matter. if it did, staggering the central seams would be more important (automatically comes w/ staggering the ends) and s&gs in general don’t even stagger these.{{however, for me personally, I could not bring myself to align joints across the ctr of a boat}}

The bigger issue for me with s&gs is just the appearance of those 90 degree panel joints.(or heaven forbid, those multiple blob joints on jobber kits) One way to compensate is to choose plywood that has a very even grain and color so that the abrupt join is less noticeable,. Other is to use slightly angled(across the ply thickness) butt joints rather than scarf to close/minimize the joint interface as much as possible(lots of painted clc yaks out there - why?).
But another way is to shape the joints so that they at least acknowledge the lines/flow of the yak. In simplistic terms, what if the joins were all angled to the max the ply would allow. So that they made like v shapes to the front or back

A while ago, ted henry showed a possible way of dealing w/ joins on the deck of a pygmy by using the ‘v’ approach but making a nice sequence of v’s morphing into a bird(artic tern).

Or in your case, what if you had not premade sheets of ply but had a 2x18 table in which you prelaid out pcs of ply so that the seams near the ends exactly duplicated the end shape – the bow seam echoing the bow and the stern the same. If the bow&stern are curved shape, double cut thru the ply. Each case is different so you may want to modify the curves/lines so there is a progression.

In the cirrus that vaclav made/shows, you can see dark paint ‘v’ lines differentiating the bow from the rest of the yak. What about playing a game w/ that approach and instead use alternating colours of ply to accentuate the bow or stern. Or what if your base ply was dark(joins less noticeable) and came up from below to become a dark bow/stern part of the sheer panels. Or vice versa, etc.

If anyone saw the carrera long stripper double kayaks when they were up, they used an interesting design response to having short strips by making strip angled or butt joins to follow a jagged flame or v pattern totally around the yak w/ a very abrupt colour change across. Was quite effective. Same thing could be done here with the panels of s&gs.(strippers too, of course)

with this one, you’re locked into the premade panel. So shift things around to their best advantage.

The other alternative is to lightly rubber glue down some thin veneer across the already made panel seams, and (double) cut down thru that veneer and the top ply layer w/ a razor knife(simple to do – easy as cutting paper). Peel off the veneer, lightly plane/chisel/scoop off the top ply to the cutline and glue down the veneer perfectly in its place. With this game you can choose any join shape - irregular, angled, multiple, curved – irrespective of the straight boring real panel join. In fact if the veneer is as strong as the ply layer removed(and why not similar?) the joint is now stronger than the previous butt a partial overlap jt.

That approach obviously could be used for any scarf joint that does or does not exhibit a little too much glue line or irregular edging.

And there are lots of other ways of looking at this. The first step is the one you’ve made by thinking about the issue. Your next yak and even this if you want, can’t but help reflect this or your other thoughts.

-mick