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Author Topic:   Foam Hull Construction Methods

Matt F posted 03-06-2009 04:53 PM ET (US)
With all the discussion about the properties of uni-bond and foam filled hull versus the method used in Everglades and Edgewater boats, does anyone have an understanding of why a single manufacturer can’t employ the strengths of each? Certainly, I would have to think the stringer system from the latter combined with the foam-through method would yield a superior product--at least in terms of strength and buoyancy.
I’m neither an intellectual property lawyer nor an engineer, but I don’t really see the downside on either account. Certainly Whaler can’t have a strangle hold on flotation just as Dougherty’s later ventures can’t “own” stringers – at least on a conceptual basis, I would think.
Again, given all the discussion, I was interested in others view on the subject. I just don’t see either approach as superior for all conditions/events, just as I don’t see the downside of combining the construction methods. Perhaps it is the proposition of a heretic?

Shrdlu posted 03-06-2009 06:17 PM ET (US)
There may be patents involved.
Peter posted 03-06-2009 06:38 PM ET (US)
Lack of know-how is the obstacle to doing the unibond construction method. If you don't get the process right because you lack the know-how, there is a high risk that the hull has to be tossed. Most manufacturers can't afford to take the risk and can't afford to experiment until they get it right.
The Everglades stringer construction method with pre-molded foam blocks is less risky. I believe this method is patented.
jimh posted 03-17-2009 12:08 AM ET (US)
In the Boston Whaler method, you don't really know if the foam interior is free of voids. You just hope it is void-free. Dougherty developed a follow-on technique of pre-casting the foam to fit the interior space. This tends to insure that there are no voids in the foam. I don't know if he X-rays the foam, but at least in his technique the foam surface that bonds to the hull and liner is void-free.
My guess why no other manufacturer has followed the Boston Whaler technique:
--the molds are more difficult to make, heavier, and more expensive;
--the amount of foam to use has to be learned through some trial and error. Too little foam and the hull has voids; too much foam and the hull may expand if the pressure cannot be released via the sprue hole vents;
--there are likely some still undisclosed techniques employed in the Whaler manufacturing process, although Dougherty probably knows them (and probably invented them).
I don't think the process is still protected by a patent. The original patent was filed 50 years ago. Patents don't provide protection for that long. See
http://continuouswave.com/whaler/reference/originalPatent.html
for the actual Boston Whaler patent with illustrations.
In the modern Boston Whaler boat there are many added structures inside the hull that lend strength to it. You can think of these as stringer-like structures. The shear braces (also called shear ties) (see the patent) are also like stringers in the Whaler hull construction.
Whaler's new foam machine has given them more consistent hull foaming than ever. It compensates for temperature and other environmental factors in mixing the foam for each shot. To learn more about the process see my article on the factory tour:
http://continuouswave.com/whaler/reference/factory.html

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Author	Topic: Foam Hull Construction Methods
Matt F	posted 03-06-2009 04:53 PM ET (US) With all the discussion about the properties of uni-bond and foam filled hull versus the method used in Everglades and Edgewater boats, does anyone have an understanding of why a single manufacturer can’t employ the strengths of each? Certainly, I would have to think the stringer system from the latter combined with the foam-through method would yield a superior product--at least in terms of strength and buoyancy. I’m neither an intellectual property lawyer nor an engineer, but I don’t really see the downside on either account. Certainly Whaler can’t have a strangle hold on flotation just as Dougherty’s later ventures can’t “own” stringers – at least on a conceptual basis, I would think. Again, given all the discussion, I was interested in others view on the subject. I just don’t see either approach as superior for all conditions/events, just as I don’t see the downside of combining the construction methods. Perhaps it is the proposition of a heretic?
Shrdlu	posted 03-06-2009 06:17 PM ET (US) There may be patents involved.
Peter	posted 03-06-2009 06:38 PM ET (US) Lack of know-how is the obstacle to doing the unibond construction method. If you don't get the process right because you lack the know-how, there is a high risk that the hull has to be tossed. Most manufacturers can't afford to take the risk and can't afford to experiment until they get it right. The Everglades stringer construction method with pre-molded foam blocks is less risky. I believe this method is patented.
jimh	posted 03-17-2009 12:08 AM ET (US) In the Boston Whaler method, you don't really know if the foam interior is free of voids. You just hope it is void-free. Dougherty developed a follow-on technique of pre-casting the foam to fit the interior space. This tends to insure that there are no voids in the foam. I don't know if he X-rays the foam, but at least in his technique the foam surface that bonds to the hull and liner is void-free. My guess why no other manufacturer has followed the Boston Whaler technique: --the molds are more difficult to make, heavier, and more expensive; --the amount of foam to use has to be learned through some trial and error. Too little foam and the hull has voids; too much foam and the hull may expand if the pressure cannot be released via the sprue hole vents; --there are likely some still undisclosed techniques employed in the Whaler manufacturing process, although Dougherty probably knows them (and probably invented them). I don't think the process is still protected by a patent. The original patent was filed 50 years ago. Patents don't provide protection for that long. See http://continuouswave.com/whaler/reference/originalPatent.html for the actual Boston Whaler patent with illustrations. In the modern Boston Whaler boat there are many added structures inside the hull that lend strength to it. You can think of these as stringer-like structures. The shear braces (also called shear ties) (see the patent) are also like stringers in the Whaler hull construction. Whaler's new foam machine has given them more consistent hull foaming than ever. It compensates for temperature and other environmental factors in mixing the foam for each shot. To learn more about the process see my article on the factory tour: http://continuouswave.com/whaler/reference/factory.html