# Building a mold out of existing boat.



## Rhapsody-NS27 (Apr 8, 2012)

This is a wild idea that I have thought about, just for the sake of a discussion. While looking at some project boats that are too far gone that are made of wood or ferro cement, I thought of making a mold for a new hull. I thought of the possibility of stripping a boat down to nothing more than a hull, flipping it upside down and after smoothing out the hull, using it as a plug to make a mold to build a new fiberglass hull.

It seems to me that there are not many companies that can build only a hull for an owner to finish. To me, many older boats have the type of hull shape and design that would be more interesting than some of the newer models offered. I know of Cape George and Nor'sea, any others that make good boats?

I can understand building a hull from nothing is more about the enjoyment of building a boat from start to finish. When it comes to money, it may not make sense to others of spending so much money on a one time build of a boat that already exists but a builder could just enjoy the process. I've heard some boats cost more to build than they're worth anyway but still find the idea interesting.

One part of this idea that I am thinking is whether this type of process would infringe on a builders rights (original builder/designer) like a copyright, trademark or patent. Would something like this generally be accepted if a boat is a certain age? So long as boats were not being built as a business? Know of anyone that tried something like this?

thoughts?


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## deniseO30 (Nov 27, 2006)

Hi Daniel, 
How large? finding, transport, and getting the donor hull ready to be a plug is going to very very expensive, that is all money that could go into the build of the boat your dreaming of. Many one off glass boats are built with C-flex. I'd suggest You buy a plan from a designer rather then wing it with hull within a hull. Strip built with glass in and out is a very very strong way of building a dream boat.


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## Barquito (Dec 5, 2007)

> The Vessel Hull Design Protection Act, title 17, Chapter 13 of the United States Code


Not that this would stop a person from a backyard project.


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## blowinstink (Sep 3, 2007)

Interesting questions Dan! My initial thought is: why not try to track down an existing mold. When Pacific Seacraft sold at bankruptcy auction a few years back, all of the remaining molds sold with them. A side deal was done for the molds for the (PSC) Dana 24 which was subsequently returned to production by a small yard in the PNW. If you do a bit of research, I think you'll find that molds for a slew of out-of-production american made boats (now out of production) are floating around (sorry). Bristols, Cape Dories, Ericsons, maybe some of the PSC fleet and a bunch of others all should be out there. It is clearly a labor of love thing -- not a profitable thing -- so if you can cut the mold making corner you'll save a bit more. 

Aside from all that, I saw a video recently (can't recall where) of a boat which was built as the strip planked template from which a mold was made for GRP boats. Brian Jones might recall the details.


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## JimMcGee (Jun 23, 2005)

You might find this book interesting. Reuel Parker lays out in quite a bit of detail what's involved in building a cold molded boat.

Rather than start with an old boat, you could buy copies of plans for a classic boat from a place like the Herreshoff Museum, or order plans from Wooden Boat Magazine.

Poke around the Wooden Boat forums and I'm sure you can find people who've done exactly that.

I picked the book up out of curiosity. It's an interesting read, but you'd need WAY more hours than I have to build a boat from scratch.


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## paulk (Jun 2, 2000)

It doesn't really make much sense to buy a functioning boat, strip it down and make it into a mold for the same boat. Why not just fix up the original boat, if it's not perfect for you? It would be a LOT cheaper, faster, and easier than starting from scratch. If the boat you start with isn't "functional", look around until you find one that is. The cost of new materials alone will probably be more than the cost of a used Cape George, for example. If you want to build a boat, buying plans is a lot less expensive than buying a used boat to use for a mold.


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## Alex W (Nov 1, 2012)

I agree with paulk. The fiberglass hull is almost never what ends the life of an old boat, it is all the of systems. It should be easy to find fiberglass hulls of almost any design in good condition for low prices if you don't need a functioning motor, mast and rigging, sails, and other important bits.


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## SloopJonB (Jun 6, 2011)

Make that three. In the most extreme case you could clean a glass hull down to the mouldings and start again.

What you are asking about is called "splashing" a mould. It was (is?) commonplace in the small powerboat field. Not so much in sail but it was done.

AFAIK there is no law against it as long as you don't try going into business with the results, but why bother?

There is so much glass out there - hulls that were brought home & never finished etc. that it would be pointless to splash a hull.

If you want to build a boat, recently I've seen a couple of Endurance 35's, a Perry 42, an Ariel 48 and a Fraser 41 for sale - all unfinished mouldings. The Perry was floating.

That's just within 150 miles of home. I'm sure the same situation exists all over North America.

All were available for way less than the cost of materials.


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## deniseO30 (Nov 27, 2006)

then you are 4 because I said it first! Sheese!


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## deniseO30 (Nov 27, 2006)

deniseO30 said:


> Hi Daniel,
> How large? finding, transport, and getting the donor hull ready to be a plug is going to very very expensive, that is all money that could go into the build of the boat your dreaming of. Many one off glass boats are built with C-flex. I'd suggest You buy a plan from a designer rather then wing it with hull within a hull. Strip built with glass in and out is a very very strong way of building a dream boat.


DUH lol


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## Faster (Sep 13, 2005)

This has been done, of course, from time to time.. sometimes the builder just wants a new mold so does a super fairing job on an existing hull and pulls a new one. Allegedly one of our local builders pulled a hull off an existing design and sold it as their own (so I've been told)

As the others said, otherwise it wouldn't seem to make a lot of sense. Also making molds is a bit of a science and trickier than it sounds. "Alligation" (where the tooling gelcoat is softened during the subsequent layup) is a big potential disaster, getting the hull out of a mold (esp a larger one) can be quite a challenge and if the shape traps itself at all you might literally be 'stuck'.


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