solid Iroko cabin trunk

I'm building a 35' steel hull,traditional wood deck and cabin ketch.Two questions-what is the usual way to build curved cabin sides.The curve is 160mm over 4.8m or 6 in over 16ft.The plans call for 32mm timber.My timber is 4.2m-is it acceptable to scarf it?
thanks

 

Are these shiplapped planks on edge? The thickness seems excessive though.

 

Laying a traditional wood deck on a steel hull is not advisable. You can do it, but you will come to regret it sooner or later.
Scarfing is acceptable and normal. If the wood does not bend by itself then you will have too steam it.

 

I have very wide boards,500mm and up ,so that would be first choice,as it seems sacrilege not to use them.I also thought the thickness was a bit much,but I can't ask the designer C Wittholz, as he is no longer with us.Shiplap would be much easier.

 

I've got a 100mm steel deck stringer and Ash deck beams.The steel was bright blasted and got 10 coats epoxy.The covering board is laminated quarter-sawn Muninga,an african timber more stable than Burmese Teak,set in mastic.Can only hope it all lasts well

 

It is not about lasting, it is about leaking. I hope you installed the covering board on welded screws.
Anyway, back to the cabin house, what wood species was specified and what are you using? 32mm of very soft cedar is different from 32mm of african hardwood.

 

Mahogany was specified,at 1&1/4 inch.

 

Well, iroko is only a little harder then real mahagony, so I don't think it makes sense to reduce the thickness. If it does not take the curve naturally you will have to steam it in form. Alternatively you can laminate with thinner stock, that will also take care of the scarfing aspect.

 

John, could you post a few photos please of your build progress to date?
I am sure that everybody on here would like to see them.
No doubt you will receive lots of opinions as well about the construction method!
As Rumars mentions, the joint between the steel and the timber is always going to be a potential trouble area, no matter how many coats of epoxy the steel has.

 

I have never steamed Iroko. How well does it bend?

 

It depends. Green Iroko bends pretty well (but it's not oak or ash), klin dried can be very difficult. Grain is also a problem, the wilder it is, the worst it behaves. Laminating is the preferred option usually, at least with the klin dried stock that is normally imported.

I think I know why he has to use such thick planks, the deckhouse is probably set on the planked deck and fastened with tierods that go from the roofbeams trough the cabin sides to the carlins (or some variation of that).

 

Iroko is not one of the steamable timbers-I/we have steamed 1000s of chair components to a gentle,unpredictable bend, using a backing strap.I guess I could do a cabin trunk,but don't relish the task.As per my original question-what is the usual way?Does brute force work?(ie. bending the timber into position and scribing off lines and bevels)That seems almost as hard.Laminating thin stuff seems easier,but I don't have thin stuff that wide.I see photos of these classic yachts with beautiful varnished cabin sides and would like to emulate them,for what its worth.

 

I'm always working with kiln dried Iroko.The plans don't specify tie rods,but I would like them.If all goes well this is a blue water yacht I'm building.

 

You can re-saw the planks in half and then laminate them.

 

With dry bending (brute force), only experimentation helps. Steaming (with backing straps if needed) was normal. Laminations do not need stock that wide (you could resaw your stock) just edge join the face veneers first.

What do the plans say, how are you supposed to fasten the cabin to the deck?