Frame & Planking Size on a diy Bertram Moppie 20'

[sandtoes]

I am thinking about building a wooden version of a Bertram Moppie 20' in size. What should I use for the lumber dimensions? I am just looking for some general sizes on:



Frames thickness and width
Frame spacing
Planking width and thickness (Carvel Planked)
Wood type? I was thinking all white Oak?


Thanks for any info in advance!

[paladin]

Steam bending....perhaps 1.5 inches X 3 inches

[S B]

I am thinking about building a wooden version of a Bertram Moppie 20' in size. What should I use for the lumber dimensions? I am just looking for some general sizes on:



Frames thickness and width
Frame spacing
Planking width and thickness (Carvel Planked)
Wood type? I was thinking all white Oak?

Thanks for any info in advance!
I have no idea what a Bertram Moppie is, but the safest thing to do is visit the library and find a boat building book with the plans for one similar. Use those scantlings.

[sandtoes]

I was thinking this:



Planking 1" x 3" (that would be a full 1" thick)
Frames 2" x 4" (again a full 2" x 4")
Frame Spacing 20"


I will consult a book, but would also like some opinions if any skilled builders are looking!

The Bertram moppie 31 was a legendary boat in 1960, and so was its deep v hull design, by Raymond C. Hunt, and Richard Bertram was a broker.

http://www.bertram31.com/history.htm

[S B]

Here,a boat of that size,would have roughly, Frame sided 2' molded 2 1/2" - 3", 12"centers, cut from solid timber,not steam bent. Plank 1 - 1 1/8 . Keel sided 6". Nothing, I can think of, that size,had frame spacing 20" apart.

[S B]

20' version, 1 1/4" sided x 2" frames 10"centers( cut timber) 1"x1 1/2", 8" centers (bent). Plank 5/8" - 3/4" . Keel sided 4" Locally, frames larch or spruce cut, larch steam bent. Plank spruce or fir.

[sandtoes]

Nothing, I can think of, that size,had frame spacing 20" apart.

Thanks, maybe because the design was originally fiberglass, not sure if anyone ever built this out of wood. But I will now start to reconsider my frame spacing.

[rbgarr]

John Hanson, the publisher of Maine, Boats, Homes and Harbors magazine has a 20+ foot Hunt powerboat named Buffalo Gal. It is wood, with lapstrake topsides above the chine. I don't know how she is planked below it, but I suspect it is plywood. He may have some guidance for you if you want to consider building that way. http://www.maineboats.com/

There have been others made of wood in various sizes:

http://www.yachtworld.com/boats/1968/Surf-Hunter-25-1981366/S.Dartmouth/MA/United-States
http://www.yachtworld.com/boats/1967/Surf-hunter-25-Sportfish-1796538/Tiverton/RI/United-States
http://www.yachtworld.com/boats/1967/Ray-Hunt-28-Hunter-Express-Fb%2C-Rebuilt-%2705-1988997/Harwich-Port/MA/United-States

and IIRC an 18' version is maintained at the Concordia Boatyard: http://www.concordiaboats.com/index.html

[Todd D]

Since the boat was designed for fiberglass construction, I think you will have considerable trouble with the compound curves. If I was going to build a scaled down Bertram 31, I would cold mold it. The transition from the large flat areas aft to the sharply curved, hollow, bow sections would be a real bear to plank, even if you stripped it. I know because I built one scaled down to 24" a couple of years ago.

For those that are not familiar with the Bertram 31, the hull is a hard chine, deep-V hull.

[sandtoes]

Since the boat was designed for fiberglass construction, I think you will have considerable trouble with the compound curves.

I was planning on steam bending. But who knows you might be right and I also noticed that the wider you make a deep V hulls the more draft is needed, now I think I know why builders tend to go for less dead rise and why the Bertram Moppie was narrow. I guess its all a trade off so I think I will keep it a bit narrow and stick with the 24 degree dead rise.

We will see.

[rbgarr]

Sawn frames would be sufficient for a vee hull. I don't understand why steam bending is necessary.

[sandtoes]

Sawn frames would be sufficient for a vee hull. I don't understand why steam bending is necessary.

I was saying steam for the planking IF the compound curves become a problem.