Coosa board hull (catamaran project)?

it is important to realize there is a difference between coosa and regular hull foams as well

coosa is significantly stronger for a transom than a regular foam..and it bears the quality of not rotting if a screw isn't well sealed

 

I think you should build sheated strip planked with spruce/ fir. This method has three main disadvantages, but you already told us they are of no importance to you, and two minor ones that can be cured with money. Let me explain: first major problem is rot, but it's the same for balsa or ocoume ply and you were not afraid of those, second is weight, but plywood is not lighter, and third is resale value, wich both balsa and ply have. The minor problems are speed and sanding. Speed can be improved by buying more epoxy and using a dry stripping method, sanding is faster with the proper machines or more manpower.

Now to the advantages: first it produces a smooth hull inside, no stringers and frames, this also means less filleting and tabbing. Second, it is cheap, it beats plywood by 3:1 and foam by 7:1 (approximately of course). Third, it frees you from the constrains of flat panels, any form is achievable.
I prefer fir, because it lacks natural resin, but spruce is absolutely workable. Pine is also an option, just heavier. You can buy a construction grade and spend more time scarfing to eliminate knots, or a clear grade wich is slightly more expensive and harder to find (the door and window builders buy it up directly from the mill).

 

I think there is an understanding here. My MAIN problem with a plywood construction is rot. The flat panel method and the ease of working with wood like panels is what attracts me. Regarding boat shapes, the Arrow 1200 ( Shionning) is just as close as boat **** there is out there to me, and is completely flat panel( apart cabin top). The reasons I haven't settled for an Arrow is the atroceous kit price ( 76.000 Eur for the hull materials, attached recent quotation).

 

I built a 32' Cat in foam. The hulls and decks and cabins were approximately

10,000 metal and metalwork
15,000 cores, Gurit core M
15,000 glass and consumables, various knitteds
30,000 epoxy Silvertip Systems 3...about 25% waste rate for wet bag, hurts translated to $$

powercat, but numbers are pretty good

so 70,000 usd for materials is a good estimate...the kit price ain't all that bad if they are profiting a bit and saving you work cutting out, etc

This isn't paint or anything other than raw estimate

 

What was the 10000 " metal and metal work" spent on since it was a foam built, if you don't mind me asking?

 

I love coosa, I've never purchased it in less than case quantity. Usually blue water 20 and 26 in 1/2 an 1 inch thicknesses. It's awesome for high impact deck areas (we bounce lots of steel traps off of our decks) and for eliminating wood in stringers and beams. It's also great for our main bulkhead that supports our main fishing gear.

But we don't think much about excess weight and are probably the knuckle dragging Neanderthals of the boat world.

Coosa dust is the most heinous thing on the planet, and it's a royal pita to put curves in compared to every other foam. I'd think there would be a better option out there for a hull core.

 

Unfortunately that's not true, the kit price is really heavy compared to what he can do locally. First of all 76k Euro is 90k USD, second, the price is ex VAT, tax and freight. Slovenia has 22% VAT, and it's charged not only on the goods, but also on the freight. If the container costs him another 4k€, he has to add 17600€ VAT, jacking the price to 97 600€ wich is 115 293 USD. Buying in the EU he can stay around 45k€ wich is 53k USD, or about half of what they are quoting him. He has to cut and laminate the panels himself, but that difference buys him a lot of infusion consumables and CNC time.

Stefano, if rot is a concern you should not consider anything else but foam. Contact the Diab sales point in Italy, ask them for a quote (can't promise they sell to private persons, but if not they can provide you with a list of resellers). A GL approved resin should be around 12€/kg for epoxy or hardener, there are enough options on the market.

 

All the above is correct, but I also have to add the cost of the plans, not included in the kit, 13000 AUD. I am looking at 105.000 Eur before I start.. For the same money I am designing my own cat ( with external help on calculations) and should save 50% on material.
There is also another option that I am considering which is to have vacuum infused full length panels from a local shop where all the foam has been CNC cut, leaving slots for bulkheads and other panels joints( like a lego kit where everything has its own slot and nothing has to be measured). This way I should spend still less than a Duflex and save even more time on the construction. Basically building a cat the Harryproa style Intelligent Infusion – Harryproa http://harryproa.com/?p=1845

 

That is a lot of money before you lift a hand.

 

If you can get full length panels made and transported to your build site, that would be great