Capt T! How goes the prog? All kinds of fairing questions, probably some important not being asked. Began getting cooler weekends - going up that ladder all this time - sighting the hollows on the way to another project - had to do it - facing another seasonal slog thru wind and rain.
Some guys on the net talk about osmotic gelcoat blister repair or hydrodynamic maximum lift foil section fairing, but there is no blow by blow on this hickey problem we have.
I got a six foot piece of 1/8" x 1 1/2" aluminum from the hardwear. It has a smooth sexy feel to it. I had tried the aerosol primer technique, putting on a mst of color and then long boarding. Was effective - and depressing to see the huge dark puddles left. I felt uncomfortable with the foreign substance on the gel coat. It would be useful later in the topsides game.
338 had some dramatic filling to do, some places the bottom of the swale under the batten pressed on the hull seemed 1/4" deep! The flexible bar is laid against the hull and encouraged into the mildest arc by bending the top toward the toerail. You can't bend the batten around the bilge without putting a kink in it. One time I read a guy explaining how he used monofiliment to locate the dips - you can get the whole side - but you can't fiddle, or fondle, that extra fullness that brings relief to a tired brain and a weary eye. Don't think it's only a male thing.
We had longboarded the topsides twice befor, so they were well scratched. A few hilltops had begun to show some green thru the white. And we were beginning to be well versed in the long diagonal strokes needed for any fairing.
Every 5 or 6 inches along the hull, holding the batten at the seam and below at the turn in the hull, made a vertical pencil line representing the supposed hollow you could see under the batten. Connecting the ends of these lines together outlined the hollows into 'puddles.' Prime the puddle with virgin epoxy. Wipe as much off again with terry rags befor gooping.
407 I hear is a patented mix, Tried to make up fairng compound myself from microballoons and silica. Even at a stiff 50 to 50 mix I still got serious sag. And it was a b@!*^%d to sand. So I snuck into WM and shelled out $2 an ounce for 407, mixed it into a stiff as I dared brownie dough, and spread it on. Two 15 oz (!) containers $62.
Wouldn't you know, West Systems 407 sags TOO. You hafta mix in 404, says a wag. But that's silica, says I (whatever the damn number is!) And I KNOW that stuff is a bear to sand and impossible to fair.
So, I draw a piece of sheet metal bent improvisationally into a very approximate arc across the goop. collect it on the spatula and reapply it to the skips, and keep drawing the metal across the puddle. But the more you work the stuff (you ARE pressing it against the hull, which is a good thing) the more you bring liquid to the surface.
And it sags continuously until it gets hard. Must be what the patent was for. But it IS easy to sand. It's shiney too. After sanding, the low areas are untouched and dark while the rest has 'greyed' out. Where you did a single swipe and it's thin it stays dull and no sag. Lesson # 1: do not put it on thick on vertical surfaces. We haven't much, and the sag you learn to control by not trying to fill all at once. The 407 under the 36 grit longboarding doesn't produce dust, it's a kind of grit. But it has a static stickyness to it, likes to cling.
Ahhh! but the topsides, even in this 36 grit stage are beginning to look S O O O O sweet!
One nagging question. Is that this relatively soft stuff is going on to a very hard surface. That's the question. Now, we will sand this stuff back as far as we can. Maybe even flatter than Alberg's rounded curves you can see on the lines drawings, maybe. Once it is where it is going to be it can be hardened up with plain epoxy with a little silica, maybe? That's a question. I'ld say that nearly half of the topside surface is chocolate colored at the present time. That's a question.
[After experimenting: 407 can be made up extra stiff, non sag, and pressed on the surface, but maybe not with the comfort of being sure of a bond that a wetter mix will have. Sanding 407 does produce dust - not airbourn dust. The tarmat under the boat is pink with the stuff.]
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