On Tue, 03 Oct 2006 03:07:27 -0700, ray lunder
wrote:

Ahoy, I'm hoping to make a wooden cap around the combing on my
cockpit. The combing top is about 3" wide and kind of an elongated
horseshoe shaped arc which measures 16 feet in total length. I started
by tracing flooring paper, then transferring that to eighth inch ply
scrap, then 3/8" wood in 2 foot sections checking each stage. The
curve is always off even on these short runs. Significantly off. Any
suggestions? I built two wooden curved sliding cabin hatches and the
cap rail sides and tops without any real problems but this is giving
me grief.
Thanks as always.


I suspect that you are capturing the cross section area of the
coaming/cap perfectly well, but you are losing the variation in
curvature, so that the result does not match.

One way I suppose of holding on to the varying slope is to make
a thin ply cap in multiple copies and to glue them up in situ, to
capture the slope.

You won't be thrilled by this approach - ply is not a solid cap to the
eye.

Supposing that you cannot place the cap stock in position to
trace the outline (which seems unlikely) there is a gruesome
alternative: measure the profile, then measure the slope every
few inches, and make a pattern of the coaming on wihch you
can make the cap.

Brian Whatcott Altus OK