Barrelback 20 Ken Hankinson Design

[Ted D]

Hi guys: I'm building a Ken Hankinson design Barrelback 20. I've finished the framing and screwed and glued the battens; about ready for the planking. It will be 1/8" mahogany. I have about 29" between the frames. Is there some reason why I can't make the 1st layer of planks 29" wide to reach from frame to frame (ctr to ctr) to avoid any seams between the frames? On the photos I've seen the planks seem to be narrower; but It would seem to make more sense to extend them frame to frame for strength and less labor. Thanks Ted D

[Bob Perkins]

Hi Ted,

I'm building the Hankinson Biscayne 23.

The reason you can't have 29" wide planks is because the 3mm ply (or anything) will not bend into a compound curve between the frames. I used Okume for the inner layers (and anywhere that would eventually get painted) - then 1/8" Mahogany for the final layer.

For the strongest cold molded hull, you should use strips in all of the curvy areas - you could get away with larger flatter pieces toward the rear on the bottom I would figure.

I started my first layer 45 deg to the centerline, then the second 90 deg to that one.

If you like, take a look at my imagestation site: Biscayne 23 (http://www.imagestation.com/album/?id=4291051329)

And you can see how I did it if that helps.

Where in MA are you? I'm in Billerica..

Regards,
Bob

[Ted D]

Bob: Thanks for the info. It would seem that the wide planks are ok for the flatter aft section of the boat, but toward the stem narrower planks must be used because of the compound bends. Do I have this straight? Also, Bob, They recommend 4 layers so I thought I would run one layer vertically, that is keel to chine, the next two layers 45 degrees opposing each other; then the last fore and aft. The sides, of course, require only three layers. I'm also trying to keep the costs down. Maybe something a little less expensive for the inner layers. By the way I'm from Holden, and it was nice to hear from you Ted

[Bob Perkins]

You have it right, up near the stem I had to go to 3-4" wide planks to get them to stay put - and that was some work too..

On the bottom I didn't worry about the keel to chine direction I just made sure the 3rd layers seams were not directly above the 1st layers seams.

It is more important to have full glue contact and no air pockets/voids between laminations. The 1/2" bottom (and 3/8" sides) are amazingly strong when it is all done.

The 3mm Okume is super strong for your inner layers. I'm not sure what other choices there are - but Bolter plywood (somerville, ma) often has lots of beat up sheets that they discount. You are just going to rip them into strips anyway. So it works out.

Good luck,
Let me know if I can help in any way.
Bob

[Ted D]

Bob: Thanks again. I tried to look at your photos but I'm not on the premium membership list. Whatever that is... Okume sounds like a good choice. The offer to help was welcome indeed. I'm a little nervous about this. regards, Ted