Composite Hull

Being back in the boat market, I've tried to re-educate myself on what's out there in terms of power, electro-mech systems, etc. The one thing I never spent much time on, but feel a need to do so now, is hull construction. Though a long time advocate of steel, my budget pretty much precludes a steel hull. However, I have run across an interesting boat with what they broker is calling "composite".

My research thus far has led me to some interesting reads. So, for the sake of this discussion, here is how the broker is defining it for this boat:

West System epoxy cold molded process, involving 3 layers of 1/4" marine mahogany plywood saturated in epoxy/resin with complete encapsulation. This process produces a hull material that prevents water intrusion, is not subject to blistering and is both stronger and lighter than fiberglass. The entire hull is then covered in 3 layers of glass mat prior to the Awlgrip finish.

Click to expand...

They then go on to mention the use of this style of composite by Buddy Davis and Jarrett Bay. The boat is a Bruce Roberts design, and was built in Canada by Kevin Williams.

Except for my ignorance on the hull construction, this boat appears to meet/exceed our needs in almost every category. That's a big deal... especially if The Admiral seems to be happy

So fellow TFers, what say you on this type of "composite", pro or con? I value all of your opinions.

Here are some pics for perusal.

cold molded can be excellent or a disaster. Just depends on the skill and patience of the builder.

It is rare to find a commercial cold molded hull due to the high labor intensive build.

If executed well, maintenance is similar to fiberglass, but much stronger and lighter as well as quieter.

If you decide to proceed it is vital you employ a surveyor who is familiar or expert in the process. Inspecting the details which are not covered up can speak to the overall quality of the build.

good luck

I've always been hesitant about this type of construction because I don't know much about them. I do know that's a beautiful boat and I hope it works out for you! There's a beautiful Huckins Caribbean by me that's been for sale for years and I'm hesitant to look because it's composite.

I had one. A 29' Sumner Craft.

Cross sectional moulds were created (like bulkheads in shape) and the boat began by being planked w 1" X 1" DF. Then it was fiberglassed all over the outside. The hull was then rolled over, the moulds or formers knocked out and fiberglassed through out the inside. A very strong and light boat is the result.

I had Willy the Willard at the time also and we had decided to move to Alaska. I kept the Willard and was a bit afraid of water ingression and soft wood in time. As it is I just have insignificant blisters.

The Sumner Craft had a 120hp Sabre and a top speed of 20 knots. Weighed 8000lbs. I found the boat a month or so ago in a corner of a marina in LaConner and it could be bought.

Some very well known brands/designers/builders are cold molded. It all comes down to how it was done and care since build. Is the builder still in business? If so, get additional details as to how it was done and products used. Then compare to how the more notable builders do it including Post and Sam Devlin in Seattle.

I echo bshanafelt's suggestion on getting the correct surveyor. Water intrusion at the through hulls, hull to deck joint and fly bridge areas is worth a good current look if accessible. Look for dark spots on the wood, much like water staining. Do I see some in the stern section pictures?

The hull design is very unusual as there is a steeply raked stem and as a result a very low WLL.

I surveyed this boat in 2003 and while there were a few issues, they could be easily corrected. She was quite well built with a couple of idiosyncrasies that i'd be interested in seeing how they held up but generally the broker has described her accurately. I have no idea what has happened to her over the years. If she's been kept up she'd be worth a look.

Cold molding is often used for custom one-off boats or for the first boat in a series which is then used as the plug for a mold. As mentioned, cold molding produces a strong light boat compared to straight fiberglass. I would like to have seen a layer of fabric under the mat on the outside.

Basically a cold molded boat is a formed plywood hull where the entire hull is a single piece of plywood. Since cold molded boats are often built from western red cedar and epoxy, the plywood is of very high quality generally exceeding the best marine plywoods.

The down sides of cold molding are that you have to keep on top of any penetrations of the outer glass skin to prevent water from getting into the wood. Secondly, cold molded boats can be a hard sell. Recently an absolutely beautiful cold molded boat sat on the market for over two years before selling for less than half the asking price. It was built by a very respected builder and was top of the line in every respect. Only apprehension about it being "wood" kept it from selling.

If the boat was well built and has been well maintained, I would no qualms about buying it, except for the possibility of a hard resell sometime in the future.

Cold molding has been around for decades. I read about it a lot ages ago when boats made this way were often written up in WoodenBoat magazine. Back then it was mostly used to make smaller boats, power and sail. For these appkications it seems to be very good.

For larger, more complex boats I would be inclined not to favor the technique. The hull itself is not an inert material like fiberglass, aluminum or steel. The only thing keeping the water out of the wood is the epoxy which saturates the outer layers of the wood cells but not the core.

As Sunchaser points out, with the myriad of hull/deck penetrations one has with a larger, more complex boat the potential for water intrusion into the wood core is oretty high, particularly as the boat ages and "works."

While the cold molding process has advantages, to me they don't outweigh the potential for serious problems over tine.

Merritt and Huckins uses this method. Both very highly respected boat builders and they get their money on the resale as well.

The OP might want to check out wood specific forums to get more opinions.

I just happened to be reading the section in Dudley Dix's book last night about cold molding. This is just a summary of what he has to say about a variety of materials but it might be of interest, Article on choice of construction material. There are other books out there that focus on this type of boat building.

There is a company in my area building boats this way. Years ago, they built a Hatteras style boat that was around 60 feet long. Huge it was and they built it in an old barn. I only saw it at a distance but the finish was really well done. They appear to be building a large variety of styles and sized boats all with this wood/fiberglass.

For a boat that needs to be light and strong to go fast, I would look into this a bit deeper. The wood is worrisome but there are no perfect boat materials. Seems like if the boat was built and maintained correctly, the wood issue should be minimized.

Later,
Dan

Marin
Many quite large boats are cold molded. One of our local builders (Brooklin Boat Yard) specializes in cold molded hulls and builds boats up to 76'. Their boats are absolute top of the line in quality and are MUCH more complex systems wise than anything any of us are likely to own.

Their latest build



Similarly, Hogdon Yachts in Boothbay Harbor, ME also builds a lot of cold molded yachts. The boat below is a 150' yacht they built using cold molding. Again, the systems on this boat make those on any of the boats discussed here look primitive and simple - I am including large Nordhavn yachts.



There are a number of powerboat builders that build cold molded boats too. Among them are Rybovich sport fishers and Jarrett Bay Custom Yachts. A Jarrett Bay 75 sport fisher summers at my marina. It is absolutely spectacular and has every possible bell and whistle systems wise.

Large, complex boats ARE indeed build by cold molding.

Thank you all for your input... by all means, don't stop!

Boatpoker, I'd be interested in learning what the issues and idiosyncrasies were you mentioned in your reply. Feel free to PM me if you want.

I've enlisted Tucker's help in this process, and we're hoping to board her this weekend and do some "yacht fondling" of this and a couple of other boats we're interested in.

Question: Since the basis for the construction of this boat is wood, would finance or insurance companies consider it as a wood vessel?

Your thoughts?

TDunn--- Thanks for the info. I've certainly heard of some of those brands. Huckins has a great reputation although they did build the worst PT boat used in WWII (it wasn't built badly, it simply couldn't perform the mission). And I've certainly heard of Rybovich although I did not know they used the cold-molded process.

My concern would be how this construction method holds up over time. Obviously, like all boats, it all comes down to how well the boats are looked after by their owners. So I would expect a quality boat to start with would still be one if it was well looked after regardless of its age. You can say this about any boat, including classics like Chris Crafts and the like that are "regular" wood boats.

High quality boats that are still in high-quality condition will command high-quality prices and justifiably so. What I am skeptical about are boats--- any boats --- that have had a much more checkered past and so have prices that tend to be more in line with what a lot of cruising boat buyers are willing to spend. That is where I wonder if the cold-molded process might be more of a potential detriment than traditional fiberglass or metal.

In 1961 I built a 21 foot cabin cruiser this way. It was a Chris Craft kit sold by Sears. Sold the boat in 1964 and it is still going strong. It has had many owners over the years and greatly abused. The current owner repaired areas at a very low cost and uses the boat daily as a commuter. This boat may out live me.

Cold molding is easier to do today as epoxy has better gap filling ability than the resourcinol of old.

An outer layer of Dynel was used to keep out wood worms better

Cold molding requires the same care as wood NO DECK LEAKS, and requires far more skill to repair than build.

"the boat began by being planked w 1" X 1" DF."

I believe that is strip planking , not cold molding , which is usually done with marine ply.

Actually cold molding is usually done with solid wood veneers not plywood. It is pretty easy to repair. You just set your router to the thickness of the veneer and rout out the bad wood. Then you glue new veneer in and repair the fiberglass overlay.

True

TDunn said:

Actually cold molding is usually done with solid wood veneers not plywood. It is pretty easy to repair. You just set your router to the thickness of the veneer and rout out the bad wood. Then you glue new veneer in and repair the fiberglass overlay.

Click to expand...

There have been several cold molded sail boats two in particular I've followed over the years. The Gemini twins, i believe they were designed by Gary Mull and have been active racing on the bay for years. One of them was just repaired at Grand Marina in Alameda just as you describe. This twin has been kept natural wood the other painted. Several dings and gouges were repaired and she looked almost good as new. Some of the restoration specialist of old wooden Chriscraft, Century, and Hacker craft and the like are refitting with what is called a tight bottom. Diagonally planked west system epoxy and thin planking tripled. If I were to build a one off boat this is the system I would use. This cold molded method of construction was developed using resorcinol glue for light strong aircraft. West epoxy is a much better glue.

Old deckhand said:

In 1961 I built a 21 foot cabin cruiser this way. It was a Chris Craft kit sold by Sears. Sold the boat in 1964 and it is still going strong. It has had many owners over the years and greatly abused. The current owner repaired areas at a very low cost and uses the boat daily as a commuter. This boat may out live me.

Click to expand...

I don't see any mention of FG. Perhaps that is why the boat has lived so long. The CC kit boats were, I belive all Mahogany or oak and mahogany ply. The wood they were made of May not be availible today. And that boat was almost always powered w two 35hp Johnson or Evinrude engines. JohsonRude as we used to call them. Every once and awhile I see similar boats on Craig's List. Thanks for posting Deckhand.

Curious as to how this differs materially with a fiberglass boat that is wood cored? Seems to me the largest difference is in the use of pigmented fiberglass or a shiny gelcoat on the wood-cored example. You still need to keep the water out and be prepared to repair any incursions quickly. Cold-molded/composite boats, until Huckins etc were mentioned, I had always assumed were hand-made.

Xsbank said:

Curious as to how this differs materially with a fiberglass boat that is wood cored? Seems to me the largest difference is in the use of pigmented fiberglass or a shiny gelcoat on the wood-cored example. You still need to keep the water out and be prepared to repair any incursions quickly. Cold-molded/composite boats, until Huckins etc were mentioned, I had always assumed were hand-made.

Click to expand...

The structure of the boat is wood. The fiberglass is thin, covers the exterior of the boat, needs to be faired and is not really structural but does help provide some bump resistance. The epoxy used to treat the wood should prevent worms from getting into the wood and certainly the fiberglass should. One does not need the fiberglass per Dix.

Later,
Dan

Eric,
Yes, I glassed the outside with too many layers by today's standards. The interior of the hull was saturated with cuprinol preservative. When I saw the boat last there was zero rot due to the cuprinol. Resorcinol glue was used and thousands of screws driven with brace and bit. The engine was a single tower of power, I believe 70hp. It was made with the finest mahogany plywood that I have seen. Ken

"Resorcinol glue was used and thousands of screws driven with brace and bit."

More common in that era was Monel staples that could be driven quicker to mthin the glue line.

The monel staples were left in place in each layer.

On a large order one could request the ply used for the hull to not be factory finish sanded , saving time in assembly.

FF said:

"Resorcinol glue was used and thousands of screws driven with brace and bit."

More common in that era was Monel staples that could be driven quicker to mthin the glue line.

The monel staples were left in place in each layer.

On a large order one could request the ply used for the hull to not be factory finish sanded , saving time in assembly.

Click to expand...

I believe the kit supplied silicon bronze screws, so that is what we used. I have built other boats using "boat nails" and glue. Overall, building boats was good for me in my teenage years. It also got me onto the water in a wild and beautiful area. The last boat I built for a friend in 2007. Getting a little old for building but would love to build one more.

Chriscraft kits were Philippine mahogany plywood and frames. There were a number of production small boats including canoes that were cold molded mostly from the midwest. Yellow Jacket , and Dumphy come to mind. The advantage of cold molding is diagonal strips being penetrated with epoxy and every 1/8 inch or so. Dry rot is still possible but greatly diminished. Also by using narrow strips the wood cells are isolated in each strip by an epoxy barrier between the strips. I'm not a fan of using plywood strip because the wood has already been stressed when it it turned off the log and flattened. The checking you see in plywood siding is caused by this. It's more expensive but stronger to use wood strips. Cold molded red cedar which has natural rot resistance would be a good choice.

After a camping/fishing trip to the Yukon years ago I decided I wanted to build a 20' freighter canoe. The following year I visited a canoe builder in Maine who advertised in Woodenboat magazine in those days and who used the cedar strip/West epoxy method of construction. He explained the process he used and showed me some of his completed boats. It was beautiful work.

In the end I opted for traditional wood and canvas construction but the cedar strip/epoxy process would most likely have been faster and easier and yielded a tougher boat.

Cold-Molding refers to a construction method where hull planking consists of multiple layers of wood laminated together using epoxy. Whether the wood is solid timber, veneer, or plywood makes no difference. Composite construction refers to "strongly bonded dissimilar materials". In modern boatbuilding, composite construction refers to a foam core with mixed skins of carbon, kevlar, and various fiberglass reinforcements. The boat in the original post is built using cold-molded construction methods, and is sheathed with fiberglass. The reference to composite is a dodge, so the broker doesn't have to mention the dreaded "W" word. It's arguable how much strength the fiberglass adds to the structure, but it's not a lot. Mostly it will add abrasion resistance and some puncture resistance.

The picture shows a section of Scheherazade's cold-molded hull sitting here in my office. She's the 154' ketch built by Hodgdon's and posted above by TDunn. I'm one of her designers. As you can see the hull is built of 7 layers, and its close to 3.5" thick in total. The inner layer is vee-jointed tongue and groove fir, 3/4" thick with the grain running fore and aft. In the middle are four diagonal layers of 3/8" red cedar. In high-load areas (keel bolts, chain plates, rigging, etc.) mahogany is substituted for the RC. The outer layer of planking is another 3/4" douglas fir running fore and aft. Finally a sheathing of fiberglass, in this case pretty heavy biax or triaxial almost 1/16th thick. Towards the bottom of the block you can see one of the plastic nails used between layers to hold them in place while the epoxy sets.

When we were living down in New Zealand I looked at a number of the locally produced cold molded hull sailboats. They were laid up using multiple layers of Kauri wood, epoxied together diagonally and stapled to hold the layers together until the epoxy had set, the black plastic staples were then sanded off leaving a bunch of little black spots that looked like fly specs.. I thought it was a great way to lay up the hulls.

They were perfectly fair and painted on the exterior and typically finished clear on the interiors. the hulls were light and fast.. and beautiful. I would rather have one than a cored F/G hull any day. They were also warm and quiet like only wood can feel. Maintained right they will last as long as anything else. I believe the Schooner Creek boats built by Steve Rander were of somewhat similar construction.

A cold molded hull isn't a "wood boat" that should be feared like a planked hull.
HOLLYWOOD