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Old 13-07-2011, 22:44   #46
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Re: Balsa Core on Cat Hulls

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Originally Posted by clockwork orange View Post
Minaret,there are thousands of balsa cored boats sailing around where the owners have no idea they have rotten core, ignorance is bliss i guess. This is one area where i would have a lot more confidence in one of the kit catamarans built by the owner down under like the Orams, Shionnings etc than most production boats. The owner builders are much more fastidious in taking care of the details than the guys working for a paycheck at a production builder.
The point here lies in the building method.. Never get in a mould build cored boat.. whatever the core.. well maybe corematt
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Old 13-07-2011, 23:30   #47
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Re: Balsa Core on Cat Hulls

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The point here lies in the building method.. Never get in a mould build cored boat.. whatever the core.. well maybe corematt
BR Teddy
Huh? What? I'm sure you'll be posting the research behind this soon...
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Old 14-07-2011, 07:05   #48
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Re: Balsa Core on Cat Hulls

In a mould you gotto put the core sheets on a ready laminated outer skin (female mould). There's no way in this working stage to be sure that there's no gap's btw them. Vacuum bagging and/or Infusion makes the situation somewhat better, but only way to be sure of perfect touch is to laminate over the core like it's done in oneoff production.. That is off course IMHO as an amateur boatbuilder
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Old 14-07-2011, 08:17   #49
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Re: Balsa Core on Cat Hulls

Teddy,

with SCRIMP the infusion happens for the core plus both skins all at the same time.

ciao!
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Old 14-07-2011, 09:56   #50
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Re: Balsa Core on Cat Hulls

When we were shopping for a cat a few years ago the Leopard 4600 had just been introduced to the market and it had great accomodation but we ended up choosing the Dolphin with no regrets. I was not confident that the balsa core below the waterline that the Leopard offered was a good long term choice for us. The Dolphin is solid FRP below the waterline and Divinicell foam core above the waterline. I like the idea of solid glass on the bottom of a cruising cat and the Dolphin will still out-sail most production cruising catamarans in its size range, although it is clearly not a race boat.
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Old 14-07-2011, 11:50   #51
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Re: Balsa Core on Cat Hulls

"it was not as light would seem as ..." I hear ya.... I've often wondered if there is really any savings in weight by the time you have an outer hull and inner hull and core. On the other hand stiffness must be remarkable.. BTW... several years a ago I look at the newer Waquiez boats. At that time they were making a hull that appeared to have an injected foam core that was very dense and about an inch thick (the foam). It was not soft but hard...you couldnt dent it with your finger at all. Anyone ever hear how this worked out? Seemed like a hell of a concept at the time... not weight savings but rigid as heck and strong...
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Old 14-07-2011, 12:17   #52
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Re: Balsa Core on Cat Hulls

Thanks Nick, didn't know the term but yes, that's the best and only acceptable way to do it in a mould.
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Old 15-07-2011, 07:54   #53
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Re: Balsa Core on Cat Hulls

Cheechako, the point i was making about that F-board was that while the weight per square foot was certainly light you have to be realistic about how and where you use it, a couple of examples of where we used it inapropriatley imho was for the cabin sole and for the cabinet fronts above the sink in the heads.On the sole we used 3/4" F-board with 1/4" T&H ply laminated to the top surface, now this boat had an aluminum space frame with all cabin sole support structure out of aluminum angle closely spaced breaking the panels up into fairly small sections, i bitch that its ridiculous taking an expensive lightweight material and then gluing on heavy T&H ply to which the powers that be say, yeah, but its still lighter than 3/4" plywood to which i reply, but who the f#%k would use 3/4", use 1/2",by the time i backfill the edges the f-board will be just as heavy but not as tough as straight plywood to which im told, yeah but plywood is not hi tech. In the other example of the cabinet face we take 1/3rd of a $300 sheet of F-board, cut out most of it to install Plexiglass(heavy)sliding doors leaving just a perimeter,then routing out 3/8" of the honeycomb between the skins on all edges and backfilling with thickened epoxy,teak veneering it and then gluing it in,what a waste, it would have been just as light to build a light wood faceframe and much cheaper and quicker. Now it was perfect for areas like bulkheads,bunk tops etc, large areas with minimal backfilling.
I dont believe it makes for any stiffer panel than foam or balsa with a comparable core thickness and skins. I would say all things being equal, the balsa will be heaviest,the honeycomb the lightest and the foam in between and all about equal in stiffness. My son is planning to build a cruising cat and we will likely use balsa for the hulls and decks,nida core for the non structural sheetgoods and plywood for the main strength bulkheads/crossbeams. There will be at least a foot of solid glass down the hull centerlines with no core for sitting on the beach.
Steve.
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