Jim Creighton wrote:

David Tyler wrote:

[sucks teeth] ... Making up full length hull panels? We're above the limit of length, I would say, and the narrower panels of a multichine hull would be floppy. It might be possible with a team of four, but altogether safer to do as Annie did and make scarphs in situ.

What thickness of ply are we looking at? What are the limiting factors for length?

I assume 12mm ply, as per SibLim and Bare Bones.

The Gougeon Brothers recommend a maximum length of 16ft for panel-on-frame construction, and say that the problem is the time needed to mix and spread glue, fix the panel and then clean up. 

David Tyler wrote:

[sucks teeth] ... Making up full length hull panels? We're above the limit of length, I would say, and the narrower panels of a multichine hull would be floppy. It might be possible with a team of four, but altogether safer to do as Annie did and make scarphs in situ.

What thickness of ply are we looking at? What are the limiting factors for length?

Chris Gallienne wrote: I made a DelftShip model of the NA29 and then converted to multi-chine. Interestingly, the principal dimensions and ratios (CLR, LCB, Cp, etc.) barely changed.

Wow!! Impressive!

I could envision this built with computer cut hull pieces joined with "jigsaw" joints. (Cut slightly loose to allow for error.) Bulkheads with joinery first, mounted on a strong back, joined with stringers, finished with the assembled ply pieces. What say, David?

Cold molding was far too labour intensive, even if the end result was strong and pleasing to the eye.

Next, I would have looked at strip planking, covered with a two layers of glass.

But, if I had it to do over, the hard chine would get my vote.

David Tyler wrote:

But I was thinking of something more akin to the NA-29 but in multichine construction.

I made a DelftShip model of the NA29 and then converted to multi-chine. Interestingly, the principal dimensions and ratios (CLR, LCB, Cp, etc.) barely changed.

David Tyler wrote:

Of course. I'd forgotten Bare Bones. Yes, this is what one would choose for racing across the North Atlantic at maximum speed and maximum discomfort.

Here is a link I found for Bare Bones: https://books.google.ca/books?id=31sRT6tbwssC&pg=RA8-PA74&lpg=RA8-PA74&dq=bare+bones+primrose+design&source=bl&ots=5Bz6hc8aqA&sig=X3H2KEcguCnchZQieFEN76v90Uk&hl=en&sa=X&ved=0ahUKEwj8oLDXvLjSAhUF0IMKHZd5A8MQ6AEIIjAB#v=onepage&q=bare%20bones%20primrose%20design&f=false