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Cowboy Sailer 28-02-2009 07:09

Cold-Molded Boats
Learning by reading the various inputs from this forum has made me consider other construction materials for a cruising boat. In particular I have come to believe that a cold molded boat is very different from a traditional wooden boat. I believe that a traditional wooden boat will take more time for maintenance than I am prepared to give it.

Both traditional wooden and cold molded boats use wood as a big part of the total material package, but the cold mold technique seems to me to be more of a composite material concept than just a wood cored fiberglass panel like in a deck or hull of an otherwise fiberglass boat.

Most cold molded boats are one of a kind and many are amateur built. This tends to keep the prices lower for boats built using the cold mold technique, particularly for amateur built boats, than a comparable boat of fiberglass construction.

I have to feel that a boat that passes survey by a surveyor skilled in analyzing cold molded boats can be relied on to give good service.

So what is your opinion; is a cold molded boat a maintenance nightmare or is it comparable to a fiberglass boat in terms of maintenance?

What other features are good or bad in a cold molded boat? I bet they are inherently better insulated and therefore more comfortable to live in.

sandy daugherty 28-02-2009 07:55

Cold molding is a master craftsman's artform. It's tough, light and strong (as in the British Mosquito of WWII) but requires exacting care to prevent small voids in the layup. I recall a cold-molded sailboat was built to be dropped from an airplane to let downed pilots sail away to safety. That's tough. But like plywood, if water penetrates one of the wood layers, rot results, if only in the one contiguous sheet or stick of wood. Subsequest freezing and thawing cracks the resin or glue and the water (now fortified with wood-eating enzymes) reaches the next layer. The WEST system tends to isolate water penetration by using smaller pieces of wood. If scrupulous care is taken to seal any new access points (thruhulls, screws, bolts, etc.) water can't find a place to start. So if you do that, and never hit anything hard enough to crack something, its great!

But: If its built by anyone but the most meticulous craftsman, or it has been around long enough to have experienced normal wear and tear, a surveyor will find water with his moisture meter or his highly calibrated plastic mallet. Then you just have to dig out the wet wood, shape a perfectly fitting new piece of the same wood, glue it back in with uniform pressure, and refinish the surface.

Fiberglass is more forgiving, easier to fix and cheaper all around. Wood is beautiful, and a renewable resource. Your choice.

boatpoker 28-02-2009 08:18

Spencer Rybovich are the ultimate in sports fishers and are cold moulded. If built properly these can be superb vessels. An excellent way to built one-off custom boats and just as easy to repair as FRP... perhaps easier and certainly no more expensive.

PS. I use a brass hammer ( uncalibrated :) )

vacendak 28-02-2009 09:27

we have built several boats of that kind in the past, and sailed with them a lot;
now a 45" cruiser is being built with same technology:

from practical experience I'd say that if you use good raw materials
(I mean high quality wood, marine grade plywood, good epoxy etc.) and
do the work carefully, then this boat will serve you well and require no more
care than a fiberglass boat; in fact, the only rule you must keep up to is:
keep your bilge dry - which is not a bad idea in any case !

such hull, IMHO, is also stronger, nicer, and gives more inside comfort than fiberglass.

skipmac 28-02-2009 09:36

I have been intrigued by the idea of cold molded boats for years but never had the time or opportunity to buy or even sail one. The concept certainly sounds good, the beauty and benefits of wood without the headaches. I have read that cold molded have much better insulating properties than glass so warmer in cold climates, less condensation, etc.

vacendak 28-02-2009 09:48


cold molded have much better insulating properties than glass so warmer in cold climates, less condensation
Second that ;)

delmarrey 28-02-2009 10:32

All I have to say is......
3 Attachment(s)
New ones are nice! Old ones are NOT!

But here is a real nice one of Karri. :smiling:

Marinheiro 28-02-2009 10:43

not to offend Delmarrey but it is "Kauri", the yacht pictured looks like a Bruce Clark design built by the Wilsons - Karri is an Austrlian hardwood.
For a range of cold moulded construction examples you cannot look past New Zealand.
Triple skin kauri hulls were being built in NZ more than 100 yrs ago and are still sailing today - have a look at
in the 1950's this advanced onto glued construction of 2 or 3 skins over laminated frames & stringers, later still in the 80's the frames were substituted with a thicker longitudinal skin with one or 2 diagaonals over, typically covered with a light glass cloth and epoxy resin.
Few problems with the hulls, only if freshwater was trapped by stringers, more problems where plywood was used for the decks with holes not being sealed properly

delmarrey 28-02-2009 10:49


Originally Posted by Marinheiro (Post 259650)
not to offend Delmarrey but it is "Kauri", the yacht pictured looks like a Bruce Clark design built by the Wilsons - Karri is an Austrlian hardwood.

You are right. Got the spelling mixed. :o

swabbmob 28-02-2009 11:36

I have a custom cold molded 46 footer which was built in 1973. She is absolutely beautiful and after living on her for almost a year now, I gain a better sense of her strength and quality every day. Knowing that she would require different maintenance than a fiberglass hull, I began studying cold molding and also wooden boat construction. I have fallen in love with wooden boats in general, and am glad I chose her. Other than keeping an eye out for trapped moisture, I think the hull is pretyt maintenance free. The previous owner did have the bow stem rebuilt, and he had it done right. My survey didn't reveal any issues. The fellow was very thorough in tapping the hull.

Granted, because cold molding is not well known or understood, it probably scares many potential boat buyers away. That is too bad, because they can be incredible blue water boats.

Jim Cate 28-02-2009 14:04

Modern timber coinstruction... a good way to go
Good cold molded boats are really very nice:strong, light, stiff and if done in Epoxy, not sufferers of the dreaded pox. But, IMHO there is an even better method -- strip-plank composite. Our Insatiable II is built thus, using 25mm square strips of Western Red Cedar, soaked in epoxy, laid over laminated frames and glassed inside and out. The glass is pretty thin, except in high load areas and in the bow where it is considerably beefed up. Won't go into the details, but she is now 19 years old, has done a LOT of sea miles including Japan-Aleutians-Alaska, and shows no signs of flexion or water penetration. Her hull is way stiffer (in the flexing sense) that our previous boat, a Palmer Johnson 36, built in tank-like GRP/foam. No creaks or groans rolling downwind in big seas and so on.

Not that I'm prejudiced... but I do think that strip plank is the very best way to build a one-off yacht, followed closely by cold-molding. Repairs, despite the worry evidenced above, are not particularly difficult when compared to GRP. If ease of repair is your criterion, then go for steel -- weld it up anywhere. And yes, as always, a boat built by a really good shipwright will be better than one built by someones' little brother who flunked wood shop. And that applies equally to any form of construction!

The need for a comprehensive survey is equal to any other sort of construction. The findings of an expert who isn't suffering from boat lust should guide us all before signing that line.

So, if you find a good cold molded or strip planked boat, you are indeed in luck... go for it!


Jim and Ann s/v Insatiable II lying Gladstone Qld Oz

Maren 28-02-2009 15:25


Originally Posted by Cowboy Sailer (Post 259594)
So what is your opinion; is a cold molded boat a maintenance nightmare or is it comparable to a fiberglass boat in terms of maintenance?

I think cold molded is a fine technique but, as I see it, the real benefit is the wood-epoxy combination. The epoxy effectively counteracts wood's real weakness of rotting. Wood is light and strong. Plywood is less strong than solid wood overall but stronger in more directions. It’s a good compromise.

As for the technique of cold molding itself, I suppose it depends on what exactly you value. There are faster methods of construction -- cylinder molding comes to mind and, depending on the number of chines, other methods like stitch and glue. If you are concerned about repairing a hole in the hull and think (rightly) it would be more difficult to fix, there are methods easier to fix. There really isn’t a single material, method or design that is ideal on all points of evaluation. That said, my boat is wood/epoxy too.

Wotname 28-02-2009 15:27

To clear up a couple of misconceptions posted above regarding water and wood.

Water is not (repeat not) the enemy of wood. Do not be put off cold molded / strip plank / epoxy encapsulation etc by the fear of water.

Seawater is fine around wood - witness centuries of wooden boats (before epoxy). Yes worms were an issue back then before modern antifouls but the seawater wasn't the problem.

Even freshwater isn't huge problem but it CAN lead to rot if allowed to collect and the area is not well ventilated.

However having to choose between a well made strip planked and a well made cold molded boat could be a huge problem - I am not sure if you could ever be sure that one was better than the other - both are near perfect IMO.

Jmolan 28-02-2009 22:15

2 Attachment(s)
Chris White reported after ten years his cold molded (constant camber) 52' trimaran was as good as the day it was si a wonderful method of boat building.

Amgine 01-03-2009 09:37

Disposable boats
One of the things that people in boating cannot seem to get their heads around is that a traditionally built boat was a disposable item. Solid wood was (in many places) cheap, labour was cheaper, and everything that wasn't wood was salvaged - even the nails. In that economy you built a boat knowing it was going to be replaced within 10 years - sometimes even within a single voyage.

The need for cold-molded boats arose first from a desire for speed - they were lighter. Then because they required less-skilled labour. And now, as we try to build boats to last a half-century or more, because they can be long-lived. But they aren't going to last as well as the mostly-inorganic and inert fibreglass, and they aren't going to be as cheap as the unschooled and unskilled yard employees or the fibreglass factory robots.

A couple I knew threw together a gorgeous carvelle hull in 3 months. They went from paper drawings to the South Pacific in just over 3 years, and they spent a bit over $30k. Their boat won't last, and they planned to sell it when it's 10 years old or whenever they get back, whichever comes first. I haven't heard from or about them for 7 years, but I'm not sure, if they'd decided to build their boat cold-molded and to furniture standards, they'd be on the water yet.

Wood is a wonderful material. It can outperform pure carbon fibre in some composites. But it isn't holy, and you need to keep the goal in mind.

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