*THE HULL TRUTH is the world's largest FREE network for the discussion of Boating & Fishing. Whether you're researching a new boat, or are a seasoned Captain, you'll find The Hull Truth Boating & Fishing Message Forum contains a wealth of information from Boaters and Sportfishermen around the world.
Welcome to the updated THT!
If you are having trouble signing in, please email feedback@thehulltruth.com with your username and we will help you. We thank you for your patience as we help you access the new site!
Random Quote: I don't want to be rich! I just want 1 dollar more than I can spend
Most fiberglass boats have layers of fiberglass laid in molds after gelcoat is applied.* The boat generally "cures" in the mold and the chemical reaction between the resin and catalyst creates quite a bit of heat.* Curing in the mold is suppose to be superior and helps the hull retain shape over it's life.
Cold molding uses no mold, and several (usually 3) layers of thin veneers are applied to create the shape.* There are various adhesives to hold the veneers in place.* The boat is then fiberglassed.* The advantages are that "custom" boats can be built this way without the mold cost.* Molds are expensive to build, and cannot be justified for a one off or limited run.* The output is usually high quality, but there is a wooden substructure that could get wet if the hull is damaged.* If so, you could be in for expensive repairs if the wood should rot.* Benefits:* great process to allow customization, and a solid structure if done right, the negatives are lots of wood below the waterline with the potential of rot and big problems, higher negative hull performance problems (as the hull is hand crafted it is difficult to determine how much on the water testing was done), with molds (plugs and protos are made to check performance, not possible with cold mold).
Do a google search and I'm sure you will find plenty of info out there.
__________________
06 Grady White Marlin
"Once you own a boat, everything else in life is reasonable..."
Rot is really not much of an issue with modern cold molds; everything's sealed in epoxy and glass. Compared to molded glass, weight drops and strength increases. Look at the very best boats built anywhere by anyone: Rybovich, Whiticar, Merritt, Jarrett Bay, ect. and you'll notice they're cold molds. Downside is cost, they can be more expensive (not always) and wait--usually you'll have to order a boatand partially pay for it a year or two before delivery. And, you won't find many under 40' or so, as smaller boats are just too expensive to build with this method and make a living at it. Ride one in rough seas and it's pretty easy to determine that they perform better than molded boats, in most cases, all other things being equal (which, of course, they never are!).
The only other disadvantage is the space in the cabin if you are looking for a smaller custom cold molded vessel 40 feet or under. Between the large bow flare of most of the builders and the ribs of the frame, quite a bit of room is lost. But if you are looking for a larger vessel and have lots of money and 18-24 months to wait it can be very rewarding to completely customize the boat for your needs.
When fiberglass was firs invented, the resins needed high temperature and pressure to cure. The molds were 'baked' in a oven, or somthing similer, until the resin had cured. In the '50's, newer resins wer invented that would cure at moderate tmeperatures, down to about 60^ f. The term 'cold-mold' was coined to differenate between the two types of resin and the resulting building process. Almost all boats built today fit the origonal definition of cold-molding, because of the low-temp resins used. These days, 'Cold molding' refers to hulls that are built with a wood core,epoxy encapculated, then fiberglassed on both sides. The is no 'Mold' used; the hull is the mold. Do a search for member 'GAMEOVER' - he has posted pics of a cold-molded boat he is building. see this thread - http://thehulltruth.com/forums/threa...57962&posts=17
Pro's of cold molding - If you are buying a cold molded boat new, you are getting a coustom boat. Hulls will be every bit as strong as a 'regular' hull, but it sould be a bit lighter - so you will need less HP and get a bit better gas milage.
Cons - Wood, wood, everywhere. The wood should be sealed, so there SHOULD not be problems. Any thru hulls will have to be cut oversized, filled with epoxy/glass, and recut to size. (extra labor). If you leave any un-sealed holes, the wood will rot. Keep in mind that despite wood's recent bad rap, there are a lot of 30+, 50+, and some 100+ year old wood boats out there. If you take care of it, it will last just as long as a glass boat.
Question for the guys that know more about boat-builiding than I do: I thought modern cold-molded process saturated the wood with resin during construction so that wood won't rot even if the fiberglass sheathing is compromised. Descriptions here indicate that wood is merely encapsulated and make it sound like you end up with someting that isn't a whole lot different than cored construction. Can someone elaborate?
The closest to 'totaly saturated' wood ( I am guessing) would be thin, end grain balsa, cured under pressure. Even then, I don't see the epoxy soaking all the way thru, unless the balsa in VERY thin. Most cold mold boats are built with mahogeny - either Okume (lighter, most populer) or Meranti (better rot resistance). These are hard woods, and the epoxy will penitrate less than 1/16" into the wood. The wood will soak up some of the epoxy, just as it will with paint or varnish, but it does not soak totaly thru.
Also, the Fiberglass is usally several layers of thick cloth - you won't comprimize the glass with a swinging sinker or a wild gaff. The primary sorce of water intrusion is from accessorys and other 'stuff' that is screwed thru the glass and not sealed, or a thru-hull that is just sealed with a little 5200, instead of being over-drilled, sealed, and re-drilled.
Also, part of your yearly maintace will be to chech the hull for places that need touch up or repair. Cracked transoms should not happen on anyboat, but they do. With an all composite boat, you may be able to ignore a non-structrual crack, but on a wood core boat, they MUST be reapired properly.
Why would a foam cored boat being any less susceptible to water intrusion damage than wood? My understanding of almost all foam core materials is that they often degrade over time from heat (boat being out in the sun) and if exposed to enough water over time they like wood , will effectively rot and lose their structural integrity just like wood which has been exposed to water will.
Boatbuilding with epoxy is based upon ALL wood components being throughly coated PRIOR to assembly. A typical glass boat with wood stringers has the wood components assembled then tabbed or glassed to the inside of the hull. Problems occur when there is a breach in the glass encapsulation and moisture enters and becomes trapped between these members and if conditions are right, rot will begin. By encapsulating all sides of all components prior to assembly, there are no exposed wood surfaces that can be attacked by moisture.
Timely thread. The 32' Jarrett Bay is a low production custom boat......looks awesome any body ever been on one? I spoke to the factory on Friday....price moderately equipped (with twins) is around $210K (asking). Based on the above seems like the 38' is probably the minimum size to get the benefits without the excessive cost.
Cold molded boats using the WEST epoxy system are not only as strong pound for pound as all glass boats, they are simply beautiful. I was so impressed with a couple of friends Olympic Tornado catamarans built that way that I built my 4x8' lab sinks with plywood and WEST epoxy with a protective layer of mat and light roving and 20 years later, not a single occurrence of water intrusion into the wood. I left everything clear and unpainted so any leaks through to the wood would show up immediately as a dark area. Those are some tough sinks! They should easily last another 30 years at that rate.
From what I have read, cold molded boats are typically made on a 'male' mold - that is, on top of a mold that is shaped like the upside down hull. For this construction method, the mold can even be skeletal in form, with just sections through the hull fleshed out. That makes it a good way to make one-off or low volume hulls, since the 'tooling cost' is minimal.
They are made using layers, each layer consisting of thin, parallel strips that have been completely saturated with epoxy. The result is far superior to conventional wood construction - stronger, lighter, and highly water and rot resistant. There are no fasteners to fail.
It seems to result in a superior product, but it is far too labor intensive for high volume boats, so it's use is restricted to high end boats made in low quantities. Compared to fiberglass reinforced plastic, it's much faster to make the first boat, but slower to make many boats, because the start up effort is minimal, but the throughput is low.
Those guys at Six River Marine (as well as Dolvik) are master craftsmen.
__________________ When blithe to argument I come, Though armed with facts and merry; May Providence protect me from, The Fool as adversary. Whose mind to him a kingdom is, Where reason lacks dominion; Who calls conviction prejudice, and prejudice opinion.... ;-)
Here's a large example of a cold molded boat, a 154 footer, designed and built by Hodgdon Yachts, also of Maine:
__________________ When blithe to argument I come, Though armed with facts and merry; May Providence protect me from, The Fool as adversary. Whose mind to him a kingdom is, Where reason lacks dominion; Who calls conviction prejudice, and prejudice opinion.... ;-)
cold molded built boats
</img>
