Opinions on a cold mold hull?

[RicardoGD]

Hi. I am looking at a 38ft sailboat that was built in 2006 by the previous owner and I don't know if the hull construction is something that I should be concerned about. I would appreciate any comments on what the owner told me about how the boat was built:

The first layer of the cold mold is 1/8inch mahogany ply, followed by 4 layers of specially milled Western Red Cedar. Plans specifications were for only 3 layers of cedar. The cedar was milled by the Dean Company in Coos Bay, Oregon. The hull and deck were then covered with 2 layers of 6oz fiberglass cloth and System Three Epoxy (Seattle, Washington). The horizontal stringers were made from laminated old growth fir, 10 stringers on each side. The hull has sprayed in foam insulation to keep you cool in the tropics and warm in northern waters.

Thanks

 

[r_h]

Normally very good if well looked after - it gives a very still and lightweight structure, so is a very good build method for one-offs and low volume construction. But, in this case, I've never seen one with foam insulation and I'd worry about the potential for water ingress behind the foam, in areas that are not easy or even possible to inspect.

 

[Kukri]

The usual point of failure for cold moulding is at the deck edge. What often happens is that rain water is able to enter the laminates at the top and, since there are almost always some voids, angled at 45 degrees down, it will work its way in and start rot. This can be repaired, given time and care, if it is caught soon enough.

Careful hammer testing all round the sheer and a very cautious approach to any signs of damage to the deck edge will give a clue.

 

[RicardoGD]

Thank you! Excellent points to consider. I don't know how water damage can be inspected behind the spray foam. I appreciate your help.

 

[Keith 66]

I like cold molded construction, & have built three boats that way myself, its strong & light, as said the weak point is water ingress.
For me the warning is sprayed in foam insulation. I have never seen any sprayed or two part polyurethane foam that is truly waterproof.
All manufacturers state "Its waterproof" None of it is in practice, it all soaks up water, deck leak? water gets in, foam soaks it up, Rot starts.
If you cant see whats behind the foam....

 

[Kukri]

I also dislike the sprayed foam insulation.

 

[westernman]

The usual point of failure for cold moulding is at the deck edge. What often happens is that rain water is able to enter the laminates at the top and, since there are almost always some voids, it will work it’s way in and start rot. This can be repaired, given time and care, if it is caught soon enough.

Careful hammer testing all round the sheer and a very cautious approach to any signs of damage to the deck edge will give a clue.

Also check around all through hulls.
I had rot in my boat, which is wood composite epoxy construction, around a through hull which had been made after the boat had been delivered for the speed log.

Easily repairable if caught early enough.

I concur with the deck edge. A sister ship to mine (not Tom Cunliffe's one), although poorly looked after, had very serious issues with water ingress through the deck edge.

 

[westernman]

Also check around all through hulls.
I had rot in my boat, which is wood composite epoxy construction, around a through hull which had been made after the boat had been delivered for the speed log.

Easily repairable if caught early enough.

I concur with the deck edge. A sister ship to mine (not Tom Cunliffe's one), although poorly looked after, had very serious issues with water ingress through the deck edge.

I would like to just say that the building method is sound and nothing to be reticent about - except may be the sprayed foam.
It makes for incredibly solid and stiff hulls which are relatively light.

Rot will only be a problem around the edges. There won't be rot behind the foam - unless there is something which goes through that top layer of glass. E.g. a through hole.

Also, with a solid cold moulded hull like this, any start of rot will not spread very far - unlike a foam or balsa cored fibreglass deck.
If it has been looked after, it will be sound.

 

[slawosz]

I would look for very good surveyor that knows how to use the good damp meter. Or two - to compare results....

 

[Wansworth]

Just as an aside Souters of west Cowes made all kinds of yachts with that method I don’t know if they are still going?