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Author Topic:   Unibond Hull Technology In Other Products

jimh posted 06-02-2014 09:08 AM ET (US)
I am a fan of the "How it is made" mini-documentaries that show details about the making of many products. I happened to see two episodes recently that made me think about the Boston Whaler Unibond hull, and the products involved are rather unusual.
The first product related to a Unibond hull is Parmesan Cheese. In making the classic Italian regional cheese, the raw cow's milk is prepared and then cast into a mold, creating a large wheel of cheese that weighs about 50-lbs. During the aging process, which takes about two years, the 50-lbs cheese wheels are inspected by using a small hammer to tap on them. The sound of the tap is then judged by ear to determine if there are any internal voids in the molded wheel of cheese. This is the same process used to inspect the Unibond hulls of Boston Whaler boats. I am sure the process of making Parmesan cheese pre-dates that of making Unibond hulls, but inspection of the two molded products seems to have evolved with similar methods.
The second product related to a Unibond hull is a very high-tech cross-country ski. The skis are made by first casting a foam core. The foam blank is then cut and machined to a precise shape. Then layers of cloth laminates and resin are applied to the foam core. This is similar to the method of the Unibond hull, except that in the skis the foam core is fabricated to a precise shape and the laminates applied to it. The Unibond hull is first laminated, then its interior filled with foam. The method of casting or fabricating the foam into a precise shape is somewhat similar to the follow-on method developed by Bob Dougherty in making boat components and hulls. Pre-cast or pre-shaped foam was laid up with laminates and resins to make a part or to fill specific parts of the hull interior.

EJO posted 06-02-2014 09:49 AM ET (US)
As always Jim interesting tidbits. Thanks.
ktm3ten posted 06-02-2014 12:55 PM ET (US)
Was the 'follow up' technique that Dougherty developed as successful in the long term or short term? What were the advantages or disadvantages of his alternative mechanism? Love this kind of stuff...
Chuck Tribolet posted 06-02-2014 02:03 PM ET (US)
Aren't surfboards built a lot like that ski?
Chuck
Tom W Clark posted 06-02-2014 02:49 PM ET (US)
The Unibond process is different than the ski and the surfboard in that those are rigid foam cores that then have laminate applied to them.
The Whaler Unibond hull is two laminated skins, each molded separately then clamped together and filled with liquid expanding foam.
That is a lot like how refrigerators are made where the liner and the exterior are joined and then the void filled with expanding liquid foam.
In fact, many of the same hurdles are faced by both refrigerator manufactures and Boston Whaler. The biggest hurdle is figuring out how to vent away the gases from the foam as it expands and allow the foam to seek and fully fill all the little nooks and crannies. It is not as easy as it sounds.
SJUAE posted 06-02-2014 02:49 PM ET (US)
The product I came across most similar to Boston Whaler Unibond is industrial profiled roof sheet cladding that made of 2 thin galvanized steel sheets separated by a bonded foam inner core. The core is treated "FM" modified to not give off toxic gases in the event of a fire
Regards
Steve
Tom W Clark posted 06-02-2014 02:54 PM ET (US)
Here is an interesting article for Machine Design Magazine (from 2002) discussing some of the difficulties of filling refrigerators with foam. A lot of this applies to Whalers as well.
http://machinedesign.com/archive/foam-friendly-fridges
jimh posted 06-02-2014 05:19 PM ET (US)
I browsed the refrigerator article. I think Boston Whaler have also run into environmental restrictions on certain volatile organic compound (VOC) emissions in the operation of their plant.
Re the corollary to the aged cheese: there is a chemical reaction going on inside the cheese wheel, just as the foam in a Unibond hull is reacting chemically. The cheese just takes two years for the reaction to reach its desired outcome, while the foam in a Whaler cures (or is supposed to cure) in a few minutes.
The fancy cross-country skis must be able to flex. I wonder how the foam core holds up to all that movement.
Re Bob Dougherty's methods: in his Edgewater boats I believe the hulls were molded with the interior space segmented into compartments. Foam was precast in the (nearly) exact shape of the compartments. The foam was then installed into the compartments, and attached with adhesives or resins and cloth. The advantage claimed for this method is the pre-cast foam components could be inspected for any voids or flaws before becoming part of the boat hull. Also its attachment to the hull would be done with a strong adhesive. The hull laminate and the foam are both already cured, so the bond between them is a secondary bond, but made with a strong adhesive.
With the Whaler Unibond method, there is a risk of a bad pour of foam and of a hull to have some voids in the foam. I think that when such a hull is made, a decision is made by the production management about the flaw. Some flaws might be repaired if their location permits. Badly flawed hulls are probably the ones sawed in two and sent to dealers for display on the showroom floor. The bond between the foam and the laminated hull depends on the foam curing in place and for the hull laminates to also be slightly uncured. This permits a primary bond to be formed between them.
dfmcintyre posted 06-02-2014 05:41 PM ET (US)
During a 1977 road trip, we stopped at the Maryland plant, and got a tour from Bob. It was very interesting, as we had just took delivery on a 1977 Montauk and planned on fabricating a custom front shelter and cushions for sleeping under it.
We were able to watch a whole pour process, from the mating of the inner hull to the outer, mixing the foam, pouring it down a tube into the anchor locker area, waiting until the foam kicked and observing the vent holes eject residual foam along the gunnel every 18 inches or so, to the opening of the molds that revealed a brand new 17" hull.
I noticed that prior to the mixing, they raised with a chain fall both (now) mated molds about 8 - 10 inches, at the bow end, placing wood blocks under the metal outer mold wheels.
I asked Bob if that was to assist gravity in speeding the liquid foam to the stern. He gave me a sideways glance and asked if I was involved in fiberglass manufacturing. I said, Nope, just a cop who's bought a 17, and I just kinda guessed that was why. He said, "Good guess", and elaborated that they had to dial in a number of variables to achieve consistent pours; correct angle depending on model, ambient temp and humidity, length of time of the mixing, etc.
Very interesting afternoon, all on a whim.
Regards - Don

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Author	Topic: Unibond Hull Technology In Other Products
jimh	posted 06-02-2014 09:08 AM ET (US) I am a fan of the "How it is made" mini-documentaries that show details about the making of many products. I happened to see two episodes recently that made me think about the Boston Whaler Unibond hull, and the products involved are rather unusual. The first product related to a Unibond hull is Parmesan Cheese. In making the classic Italian regional cheese, the raw cow's milk is prepared and then cast into a mold, creating a large wheel of cheese that weighs about 50-lbs. During the aging process, which takes about two years, the 50-lbs cheese wheels are inspected by using a small hammer to tap on them. The sound of the tap is then judged by ear to determine if there are any internal voids in the molded wheel of cheese. This is the same process used to inspect the Unibond hulls of Boston Whaler boats. I am sure the process of making Parmesan cheese pre-dates that of making Unibond hulls, but inspection of the two molded products seems to have evolved with similar methods. The second product related to a Unibond hull is a very high-tech cross-country ski. The skis are made by first casting a foam core. The foam blank is then cut and machined to a precise shape. Then layers of cloth laminates and resin are applied to the foam core. This is similar to the method of the Unibond hull, except that in the skis the foam core is fabricated to a precise shape and the laminates applied to it. The Unibond hull is first laminated, then its interior filled with foam. The method of casting or fabricating the foam into a precise shape is somewhat similar to the follow-on method developed by Bob Dougherty in making boat components and hulls. Pre-cast or pre-shaped foam was laid up with laminates and resins to make a part or to fill specific parts of the hull interior.
EJO	posted 06-02-2014 09:49 AM ET (US) As always Jim interesting tidbits. Thanks.
ktm3ten	posted 06-02-2014 12:55 PM ET (US) Was the 'follow up' technique that Dougherty developed as successful in the long term or short term? What were the advantages or disadvantages of his alternative mechanism? Love this kind of stuff...
Chuck Tribolet	posted 06-02-2014 02:03 PM ET (US) Aren't surfboards built a lot like that ski? Chuck
Tom W Clark	posted 06-02-2014 02:49 PM ET (US) The Unibond process is different than the ski and the surfboard in that those are rigid foam cores that then have laminate applied to them. The Whaler Unibond hull is two laminated skins, each molded separately then clamped together and filled with liquid expanding foam. That is a lot like how refrigerators are made where the liner and the exterior are joined and then the void filled with expanding liquid foam. In fact, many of the same hurdles are faced by both refrigerator manufactures and Boston Whaler. The biggest hurdle is figuring out how to vent away the gases from the foam as it expands and allow the foam to seek and fully fill all the little nooks and crannies. It is not as easy as it sounds.
SJUAE	posted 06-02-2014 02:49 PM ET (US) The product I came across most similar to Boston Whaler Unibond is industrial profiled roof sheet cladding that made of 2 thin galvanized steel sheets separated by a bonded foam inner core. The core is treated "FM" modified to not give off toxic gases in the event of a fire Regards Steve
Tom W Clark	posted 06-02-2014 02:54 PM ET (US) Here is an interesting article for Machine Design Magazine (from 2002) discussing some of the difficulties of filling refrigerators with foam. A lot of this applies to Whalers as well. http://machinedesign.com/archive/foam-friendly-fridges
jimh	posted 06-02-2014 05:19 PM ET (US) I browsed the refrigerator article. I think Boston Whaler have also run into environmental restrictions on certain volatile organic compound (VOC) emissions in the operation of their plant. Re the corollary to the aged cheese: there is a chemical reaction going on inside the cheese wheel, just as the foam in a Unibond hull is reacting chemically. The cheese just takes two years for the reaction to reach its desired outcome, while the foam in a Whaler cures (or is supposed to cure) in a few minutes. The fancy cross-country skis must be able to flex. I wonder how the foam core holds up to all that movement. Re Bob Dougherty's methods: in his Edgewater boats I believe the hulls were molded with the interior space segmented into compartments. Foam was precast in the (nearly) exact shape of the compartments. The foam was then installed into the compartments, and attached with adhesives or resins and cloth. The advantage claimed for this method is the pre-cast foam components could be inspected for any voids or flaws before becoming part of the boat hull. Also its attachment to the hull would be done with a strong adhesive. The hull laminate and the foam are both already cured, so the bond between them is a secondary bond, but made with a strong adhesive. With the Whaler Unibond method, there is a risk of a bad pour of foam and of a hull to have some voids in the foam. I think that when such a hull is made, a decision is made by the production management about the flaw. Some flaws might be repaired if their location permits. Badly flawed hulls are probably the ones sawed in two and sent to dealers for display on the showroom floor. The bond between the foam and the laminated hull depends on the foam curing in place and for the hull laminates to also be slightly uncured. This permits a primary bond to be formed between them.
dfmcintyre	posted 06-02-2014 05:41 PM ET (US) During a 1977 road trip, we stopped at the Maryland plant, and got a tour from Bob. It was very interesting, as we had just took delivery on a 1977 Montauk and planned on fabricating a custom front shelter and cushions for sleeping under it. We were able to watch a whole pour process, from the mating of the inner hull to the outer, mixing the foam, pouring it down a tube into the anchor locker area, waiting until the foam kicked and observing the vent holes eject residual foam along the gunnel every 18 inches or so, to the opening of the molds that revealed a brand new 17" hull. I noticed that prior to the mixing, they raised with a chain fall both (now) mated molds about 8 - 10 inches, at the bow end, placing wood blocks under the metal outer mold wheels. I asked Bob if that was to assist gravity in speeding the liquid foam to the stern. He gave me a sideways glance and asked if I was involved in fiberglass manufacturing. I said, Nope, just a cop who's bought a 17, and I just kinda guessed that was why. He said, "Good guess", and elaborated that they had to dial in a number of variables to achieve consistent pours; correct angle depending on model, ambient temp and humidity, length of time of the mixing, etc. Very interesting afternoon, all on a whim. Regards - Don