I am so "sick up and fed" with filling and sanding! I no longer care how smooth the final product is! I think I should have put some filler in the first coat of resin that I sealed the foam with. That would have made the process much easier. As it was, I was sanding filled resin and unwaxed resin both. The unwaxed resin rolls off and clogs the sandpaper; filled, it sands well. (Using polyester resin.)
For filler, I used half micro balloons and half magnesium silicate (talc).
Anyway, I'm done now. I put together a little cradle out of some foam scraps, so that the hulls wouldn't move around while I'm glassing them:
John has suggested that I glass half at a time, from centreline around to centreline, so that there's an overlap along the centre, making somewhat of a spine for added strength and stiffness. Sounds like a good idea to me!
It's been a long road, it seems, but now I have two hollow foam hulls that are more or less the same shape. The curve of the top has been an interesting exercise:
The nubs are the outsides of the flats that the akas will attach to. I had no idea they'd come out looking like this. I just knew I wanted enough of a flat on the top to secure the akas firmly to.
The top radius started as a knife-cut angle which was then rounded with coarse sandpaper, followed by finer sandpaper. It feels like the same kind of process that a sculptor engages in: you take away everything that isn't the end result you're looking for. I did make a template for the top curve, but it turned out to be not quite right—so most of it is eyeballed. The ends are tricky, because everything changes as the hull gets narrower.
Here's a last look at the inside of one of the amas before top & bottom were glued together:
The upper one above is the top half of the ama. After a straight-sided channel was routed on the underside of the deck, the corner was cut off with a utility knife to make the bevel. Trying to get rid of as much foam as practical. The bottom didn't get routed at all.
Top half is at left above.
. . .
The amas are now single pieces, complete hulls. Here, one has been shaped, the other awaits the sandpaper:
The corners were rounded with coarse sandpaper by hand. A sanding machine at this stage takes off too much material. One needs to go slowly.
I could probably spend a couple more hours on the shaping, as there always seems to be a little hump here or there to smooth out. We'll see how much patience I have for that...
Well, it was good to have a plan, but the routing was more tedious than I had imagined it would be. So the bottom layer didn't get routed, and the top layer just got some.
The bottom two layers are now glued together. I set the third layer on top of them for the photos:
It's clear that most of the foam has been removed from the two middle layers, leaving bulkheads in strategic places for strength and to prevent oil-canning. The amas will be much lighter now. The for'd and aft bulkheads are situated right under where the akas will attach. The middle bulkhead is roughly half-way between those (I don't remember measuring for it).
I'm still planning to round the top of the top layer (the deck, so to speak) as in the drawing in the previous posting, so with the bit of routing and carving that's been done on its under side, some weight will be lost from that layer as well.