No, I just used the foam for male plugs for beams. We mistakingly
thought it were easier than building kiri boxes but we were wrong.
Some bulkheads would be needed even with blue foam, otherwise too
heavy structure.
A professional made new specs for the beams (www.multimart.
I strongly suggest you follow the original plans.
We covered the foam with biax glass on three sides , then made the
cap. Then removed the foam and installed bulkheads. We used glassed
ply for longitudinal bulkhead and foam(db800/16mm H80/db800) for the
small ones. Then we glued the cap on. Result was a very light and
stiff closed box. After this we added carbon and the rest of the
glass between layers (2mm) of carbon tow. We did this in two shots,
first the top and the sides and on the second shot the bottom which
has thicker laminate than on the top. Carbon layers are staggered
towards LW hull.
Our beams are 3cm higher than on the original plans.
End result is that our beams do not have wood core, they are perhaps
a bit stiffer and they weigh not less but almost the same as BD or
RB.... and they were a lot more difficult to build. I guess the beam
design can still be optimized and some kgs saved depending on what
are your sailing conditions.
Our boat is a non-demountable. All bridgedeck structures are foam
sandwich. The longitudinal beam is very strong and of original
design, the rest is own design. We ended up to build the dinghy ramp.
It is Divinycell/ bluefoam sandwich. I Think it is extremely useful.
Not worrying about the extra weight anymore.
We have done some motoring in various conditions and the
construction feels very solid and safe. One o/b
pushes 7 knots, two 8,5 knots. Two outboards is a must.
We hit a rock with aft rudder motoring 8 knots. Lost 10cm off the
rudder tip,
rudder stock (46x46mm solid carbon), bearings and the box remained
intact. Lets see how the steering works when we have the sailing
loads on. Not much friction when motoring though.
I copied the rudder design from the french proa "Des Jours
Meilleurs".
Rudolf has done great work building our mast. Looking forward to do
sailing tests next summer.
We do not know the weight of the boat yet but the crane guy guessed
it is close to 2500kgs with batteries and outboards.
Regards,
Arttu
p.s. posted some photos , you may have a look at "Ono"
--- In harryproa@yahoogrou
<doha720@...
>
> Hi Arttu,
>
> Did you make cross beams with solid polystyrene foam?
> How did that work out?
> I quite enjoy shaping the foam for the bows on the Hp's,
> don't know if its safer with it there not realluy an issue with all
the
> bulkheads.
>
> Doug
>
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