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Tuesday, April 12, 2011

Fin Templating and Gear Interlocks

Progress continues, slow but steady. As mentioned earlier, I only get one full day per week out of my glass guy, plus another 1-2 days spread over evenings and weekends, so it goes slow. But the good news is that one side is done. I re-drilled the pilot hole and measured the thickness, and it's 1.5" - spot on what it should be. I love it when a plan comes together.

For me, this past weekend was templating time for the fins. My hull has an outer chine and the top rear of the fin needs to be notched to clear it when they are fully deflected outboard.

The first step was to measure everything out with the help of a friend. The centered fin position is parallel to the keel, so that's the first line we established. Next, we established two lines each at 45 deg off the center line representing the fully deflected positions. That gives us the center line of the fin in it's outboard position, and the interference quickly becomes apparent. But given the fin's width, the leading surface will hit first, so that's the controlling distance for the cut. So next we measured out a parallel line representing the leading surface of the fin, and used that for templating.

The first template I made with 2" foam insulation. Once I got the distance and angle right, I transferred it a small piece of plywood. See photos below. Once verified on both sides of the hull, off went the fin spec sheet to ABT for fabrication.

Now we are back to the waiting game. Once my glass guy is cleared out of the engine room, I'll confirm the actuator location, say three Hail Marys, and drill a 6" hole in the hull.

Oh, and I sorted out one lingering issue today - the reverse interlock. There's an input to the main control unit telling it when either transmission is in reverse so ti can center and lock the fins. The trick is linking it to the gear boxes somehow. ABT offers mechanical switches that can be used with mechanical shifters, but mine are electro-hydraulic. So the other option are pressure switches to detect when the hydraulic clutches are engaged. That's what I ordered, but I've been having trouble finding out what ports on my ZF hydraulics to attach the switches. Well, it turns out there is only one port, and it's pressurized when either clutch is engaged - but you can't distinguish which one. Problem.

Well, the solution isn't too bad - actually, it's pretty nice. My throttle and shift controls are made by Glendinning, and they offer an interface kit for just this sort of thing. It has cables that go in-line with the gear control cables, and provide breakout wires to a relay box. You can then wire into the relay box to tell the stabilizer control exactly what it needs to know. It's a very clean solution.
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