Sunday, April 8, 2012

Chine Fillets and Shaping the Ama

Saturday hovered slightly below epoxy-curing temperatures all day, frustratingly.  I'd sworn I would make some progress this weekend. 

You can see how the ama is a little crooked.
I figure the traditional boats made do with what
they had available, and they sailed fine.
Right?  If it doesn't work out, I think I'll probably
just make a foam & fiberglass one for version II.
Well, if you can't work with epoxy, you can at least work on the other parts of the boat, right?  I pulled the ama (outrigger log) out of storage and went after the ends, which I'd done only a little rough shaping on before.  After a bit of work with saw and rasp, I was pretty happy with the shape.


Stern end of the ama is a little fatter than the
bow, because most of the boat's weight will be
carried aft (I think).
  
I pulled out my 1950's-vintage Craftsman belt sander and did a bit of general sanding along the length of the  ama so that it will be ready to paint.  I'd call that effort about half-done; I stopped because the old sander was starting to sound like it needed another overhaul.

Today warmed quickly to around 75 degrees, and I had a fairly open schedule, so I lowered the hull and prepped the chine fillets.  This involved sanding the epoxy-coated plywood I'd be laying the fillets on, hammering the copper stitches down so they wouldn't protrude from the fillets, and masking the entire length of the chines so that I can have a nice clean edge when I'm done. 

I also masked the benches, thinking I might as well fillet them into place while I'm at it.  And I prepared the lashing pads for installation - I forgot to put them on the panels before stitching the hull together.
Chine fillets done.  Note how smooth they are,
compared to the bilge fillet.  Also visible are
the lashing pads (clamped in place) and the
bench fillets.


Finally, I began mixing and applying fillet epoxy.  I've hit on a pretty dependable recipe - 4 pumps each of hardener and resin, then 3 little cat food cans full of microballoons and 3/4 of a can of silica thickener.  The resulting paste is workable, but doesn't sag or flow much at all, a vast improvement over my earlier efforts.

It took 4 batches - 16 pumps in all - to fillet both chines.  Then I changed over to microfiber & epoxy to glue the lashing pads to the hull.  Unfortunately, I grossly overestimated the amount of epoxy needed to do that job, so I was facing the prospect of about two pumps worth of waste.  I hadn't done the benches yet, so I scrambled to mix in the thickener and glass bubbles that would allow that. 
The somewhat gloopy bench fillets.  Since the mix
was so wet, I won't be able to remove the tape
until tonight at the earliest.

Of course, my trusty recipe was off because I was starting with an unknown amount of resin (after applying some to the pads).  So I ended up with a somewhat drippy mix that produced a nice, curved fillet but dripped down the sides a bit.  Cleaned it up with a paper towel as best I could, but I expect there will be some remedial sanding required to fix the drips when it's all cured.

All in all, a very productive weekend.  Looking ahead, there's a bit more filling and sanding to do on the fillets, then I'll be fairing the outside of each, and then (finally) it will be time to fiberglass them.  But I'm almost out of glass balloons, and getting low on epoxy, too.  So I will probably need to place an order for some supplies first.