Rubbing Strake

[CES]

Hi, I had a go at posting this on the PBO forum, with no results:
I have to replace the timber rubbing strake on a 22Ft GRP hull with quite a bold sheer line and a canoe stern (colvic motorsailer). The strake and toe rail are all one piece, so its approx 150mm x 50mm thick in section, with about 1 in 5 bends, in both directions. I'm wondering, If I steam, can I do this without laminating, and if so with what wood?

I understand from searching past threads that teak, iroko and oak are options, given the sizes above, what would be best?

 

[Peterduck]

I think that trying to bend a section that big is a big ask, and I wouldn't contemplate doing it without laminating as well. For steming or boiling [and boiling is the more effective] you need green wood, full of sap. The process of either steaming or boiling seasons the wood, so you need it to be as wet right through as you can possibly get. This pretty much writes off iroko and teak, leving oak or ash as your best chance. You are fortunate in that these are both excellent timbers for bending. Not all timbers are suitable.
Peter.

 

[CES]

Thanks for that Peterduck, do you think two sections 25mm thick would be appropriate as a laminate?

 

[rjp]

I've successfully steamed and bent approx 50x50mm iroko about 12ft long (excuse the mixed units!) so it can be done, but I imagime 50x150mm would be a bit of a handful. If you do try it 1 hour steaming per 25mm thickness is the rule of thumb. There's a guy in the states who wrote an article on steam bending and was quite encouraging when I emailed him. His name escapes me for now, but PM me if you need more info, I could probbaly dig it out.

John

 

[Peterduck]

As you will be in two planes at the same time, I would recommend that you use three laminations of 2" square each. Even then I would rip them in half longitudinally where they have to go around the tight bend at the canoe stern. I can't give you any guide as to how far to rip them, but it is only over the tightly curved part. Boiling is more effective than steaming.
Peter.