Part of the thinking is that it will as you suggest, allow the use of low density XPS, and the other is that the "ribs" thus formed will take the place of stringers when building a design intended to have stringers. My experiments with low density XPS show that the proper compression methodology results in a very tough resilient outer surface. Considering that the cost is about 10% of the cost of Divinicell, it makes sense to me.... your mileage may vary, to look into how to utilize it. That's enough money that I'm not reluctant to invest in reducing the cost. It may mean adding an extra ply or two where impact can be anticipated, or even some carbon fiber. The cost of the foam my be 10% of the cost of Divinicell, but of course the cost of the finished product will be quite a bit more than 10%, both in materials and labor. If a viable solution to this can be found, it could benefit many people. On man said he wouldn't set foot on a boat built from blue XPS....... Nothing would please me more than to be able to rub his face in that statement by sailing around the world in one ;-).......... the taste of crow...
H.W.
On 07/06/2018 10:05 AM, Björn bjornmail@gmail.com [harryproa] wrote:
I think it's a good idea. I've been thinking about it as well. But it's a lot of manual work, and maybe this stiffness isn't needed. Well, at least not with a normal skin thickness or core material. I guess that with this method you could have a super thin skin, and maybe also the lowest grade XPS core. The "webbing" will have twice the skin thickness or more, depending on how the glass is wrapped around the "planks", so will be strong enough for the shear load even without a core, probably.
A similar method would be to make cuts in the foam at regular intervals, and push glass through these cuts. Lets say cuts of 5-10cm/2-4" at 5-10cm intervals, or so.But I'm not sure if the shear load in the core is so high that these cuts needs to be reinforced with glass. Maybe the epoxy is enough? And if you make more cuts in different directions across the foam, lets say a 60° angle, then we are back to "my" idea of a honeycomb pattern in the foam. =)
On Fri, Jul 6, 2018 at 5:10 PM, StoneTool owly@ttc-cmc.net [harryproa] <harryproa@yahoogroups.com.au> wrote:
In looking at construction possibilities, I keep coming to a rather
unique method..... or at least it looks unique to me. That is to slice
the foam into planks say 15 - 20 cm wide. Wrap the individual planks
with fabric on the bias or with triax, sticking it to the planks using
spray adhesive. Then do the infusion layup, laying fabric down, then
the planks, all pushed tightly together, then the interior fabric.
Then infuse.
This of course is more work, but has multiple advantages,
especially where foams like XPS are being used. The interface between
the planks will be a solid glass rib of two plies, and this will make a
stiffener / stringer. The ribs will also facilitate infusion, creating
a flow path between the surfaces. But most important, they produce a
solid glass longitudinal shear web at each joint, reducing concerns
about core separation from the surface plies. The challenge for me at
least is the fact that the edge where the hull side meets the bottom is
going to be curved, as is the top edge.... but it's all doable, just
challenging.
H.W.
Posted by: StoneTool <owly@ttc-cmc.net>
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