: there is no reference line.

then that supports what you/we've been talking abt until now. if they did give a reference line, espec accounting for what you wrote just now, a lot of errors would be minimized - even if you couldn't follow it exactly, if the deviations were same on ea side, there would be less chance of error. and they surely know what an average deck profile is by now.

:It's like putting ply on a frame boat, you bend
: an oversized panel over the frame then attach it trimming excess. There's
: an opportunity to allow for variations in deck height should a person so
: chose to put in a tighter deck beam but I think it's oversized simply
: because that's how you'd do it with a big sheet of plywood. The radius
: isn't constant, it tends to increase at midpoint then flatten.

this happens with all constant size members/beams that bend, the curvature of the bend does not go right out to the ends. happens on strips for strippers, as well as you have noted also in sheerclamps at the bow. as well as deck beam curvatures. i conjecture it's one of the reasons you can fairly easily get deck compound curvature toward the bows of curved deck yaks as the radius of curvature naturally wants to flatten based on above and therefore more side profile/compound bend can be introduced. most espec w/ long fine ends.

: There's a
: funny thing going on conceptually,,the radiused deck beam would imply that
: the deck shape is conical but actually the plywood would rather take a
: portion of a cone at the bend in the center then developing into a
: straighter section at the sides where the leverage on the wood lessens.
: You can see the difference in what I'm talking about if you look at the
: deck of an Arctic Hawk. The deck at the front of the coaming develops from
: a simple three point bend, there's no attempt to approximate a portion of
: a circle. On the Chesapeake the deck is put onto an actual portion of a
: circle at the deck beam but what happens forward from there changes a bit.
: A big source of tech calls was the observation that the radius of the deck
: beam and forward bulkhead were different,,,you'd think they should be the
: same. I'm not sure of the original reason for the forward bulkhead being
: the radius of the underside of the deck beam but I think it made for less
: gap filling with goop with a tighter bend. If a person wanted to get anal
: about getting the sheer panels to some theoretical perfection I could
: imagine bending the side panels on a huge bending jig,,or forms,,but it
: would be easier to separate out the method of attaching a deck from the
: development of the hull shape.

by using a tighter curve more forward, it is counteracting the natural stresses you're mentioning above. aside from space issues, it would make more sense to use less curvature at the more forward locations. it would be interesting to see how far you could lessen the more forward curvatures and therefore how much more compound curvature you could get in the yak profile.

one of the reasons i don't like the appearance of many curved radius deck yaks(very generally) is that sitting in a normal(not sprint, not greenland) way with the knees and feet splayed outward, the deck/hull intersection is more comfortable the less acute the angle of intersection of the two. multi panel deck approaches can accomodate this better, and still allow a lower profile.

: When I did my banana boat I was able to get more height out of the bow
: without letting the deck fold by constructing the deck with a rib down the
: center, and was able to get more volume by cramming a spreader stick up
: forward,,but at that point a light bulb went off,,,why bother?

yes, more interesting curvatures without doing that.

one of the more humourous stories (about how curvature of a constant sized member reduces at the ends - hmm, sounds a little odd!)is me trying to keep some kind of curvature going in my sharply upturning stripyak ends. like a flipping idiot, i also had decided to have sacrificial ends so cut the yak even shorter first, and then tried to re-construct the ends. so the strips at the ends of the cutoff yak straighten out JUST at the wrong place. and then the little sacrificial end's strips are so short that they can hardly even get ANY curvature at all!! lots of makedo there.
aside from should have built at once, then cutoff, i'll leave strips/wood 6" long until setup and then cutoff.
possibly one of the reasons to let the ply deck overhangs be 3 or 4 inches, let epoxy setup over the wide sheerclamp to retain curvature, then cutoff - but too much waste.