Hi there,

Awesome - that's really helpful - I found Tom's website and have emailed
him about the scantlings rule book. Do you have any photo's of your
build - especially the ribs/bulkhead/inner hull areas? You can email me
off-list: maxh ..@.. zelhurst...com

Thanks,
Max
Max,

I am also building a 40ft. ketch. It's not intended to be 'light'
displacement, and has a D/L ration of 230. It is intended to be
structurally perhaps a bit lighter than the traditional construction
plans I started with. For strip-plank with no ribs, except at
bulkheads, Bill Garden advised 1 3/8" strips. For the same with no
ribs (except bulkheads) and sheathed in and out with 30 oz. glass, Tom
MacNaughton advised 1 inch. I suggest you get "Sheathed Strip
Construction Scantlings Rule" from MacNaughton Associates, Inc.,
Eastport Boat Yard and Supply, Box 190, Eastport, Maine 04631, USA. I
hope that address is still good. I bought the rule about 10 yrs. ago.
At that time his phone was 207-853-6049. He has a rule that easily
sets up in a spreadsheet and is based on displacement. It's designed
to build boats at least as strong as per Nevin's rule, and often
lighter.

Remember that with strip planking you need something to add cross-grain
strength. That can either be ribs or sheathing. I compromised. My
hull has several bulkheads, each with a rib. It has one rib between
each pair of bulkheads so it's not fully ribbed. It has MacNaughton's
30 oz. exterior sheathing but only 10 oz. interior, figuring I'd get
the extra strength from the ribs I have, and allows me to finish the
interior bright. I planked with 1 7/16" square strips. My planking
thickness, after fairing, is probably 1 3/8" max, less in some areas
depending on how much fairing was needed.

Max Hazelhurst wrote:
Hello all,

Can anyone assist me with the calculation for strip planking hull
thickness...? We are embarking on a build of a 40ft ketch.
Max