So where could I get a block of foam, say a 4" or 5" cube? I asked everyone I knew, and even begged a piece of polystyrene packing foam from a computer monitor, that might work... in a pinch.
And then a miracle occurred: someone discarded two giant blocks of urethane foam at the marina recycling center. I grabbed one, and cut what I needed from it.
|Big block 'o foam|
|Foam is already shaped here|
Now, to shape the foam... how to do it? I devised this plan:
- Hold a block of foam in place where I think it should be (mark the hull so that I can locate it there again). This has to be a place that is close enough to the quadrant to avoid interference problems with the nearby exhaust hose, and far enough away from the quadrant that it won't be hit by it when the rudder is hard over.
- Using a straightedge laid across the rudder quadrant, mark where the plane of the rudder quadrant crosses the foam
- Remove the foam and cut on the line I had marked
It took two tries, but here is the result (the black dot is where the center of the transducer goes):
|Weird shape, empirically derived|
It wasn't easy working in the small access hatch.
(By the way, that nasty rust stain is from a standard plumbing elbow that one of Eolian's previous owners had installed on the exhaust hose to mate up with the bronze discharge fitting. I replaced that rotting mess with a fiberglass elbow a long time ago.)
Now all I have to do is glass it into place. But that's why there's next weekend...