I once had to order a set of plans from Sparkman & Stephens for getting a boat USCG certified to carry passengers. They were understandably very guarded with their plans because they do not want someone building a boat using their design without their authorization. In the end they did send me the plans for a little more than the cost of printing and shipping
with the understanding that I was not planning on having another boat built.
The best thing may be to take profile photos of the hull
from the exact X, Y and Z planes of the hull
and then superimpose a grid over the photos so you can better quantify the dimensions. Put something in the photo
that is a known width and height. Of course get back far enough from the hull so that the stretch effect of being in close does not throw off the ratio of the true dimensions. To detect this, put something of the same dimensions on the hull at the edge of the frame and the center of the frame and then see if they end up the same size in the photo
. Of course you will also want to send plenty of time with a tape measure confirming different dimensions.
Hopefully this can get you close enough to do a scale model.