Sunday, April 17, 2011

Actuator Alignment

Today was alignment day. There are three dimensions that need to be taken into consideration.

The first is the rotational position of the actuator assembly. You can spin it 360 deg to any orientation you like. I've got a forward bulkhead to deal with, and it has a finished panel that sticks out over the actuator. Installation and removal of the full actuator requires removing the panel, including all the equipment that will be mounted on it. Fortunately, it shouldn't need to be removed except in extreme circumstances. For normal maintenance and repair it stays in place. However, the hydraulic cylinder, locking cylinder and pin, and top mounting late all need to be removable for periodic maintenance and repair. They need to be removable with the bulkhead in place. The trick is to rotate the actuator assembly so none of these parts are blocked by the trim panel.

Normally you do this by temporarily installing the actuator, but man is that thing heavy, and I don't want to risk damaging it or smashing into something else in the boat. So I made a template. I printed a 1:1 scale drawing of the actuator, cut it out, then pinned it to a piece of plywood. I traced the outline, then cut the plywood template. With the plywood template in hand, I pinned the drawing back on and drilled the mounting holes and placed bolts into three of the holes to locate it.

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ID:	26260In the first picture, you can see the template and cartoon actuator sitting on top of the castle mounting plate. With it, I was able to easily play with different rotational positions of the actuators, and using another scrap of plywood in place of the bulkhead trim panel, confirm that all the removable parts would clear the bulkhead. I was also able to confirm access to bolts and clearance for hydraulic hoses. Speaking of which, I'll need to move the hose ports to the opposite side on the locking pin cylinder, otherwise they would hit the bulkhead. There are ports on both sides, so I just need to swap the fittings and plugs.

The next trick is to be sure the actuator can be installed and removed, and this posed a problem. In the picture you can see the vertical brace that the bulkhead trim panel fastens to, and you can see that when lifting the actuator straight up would crash into the brace. The black line is where it will need to be cut back for clearance. Once the actuator is up that high, it can be tipped sideways and pulled out.

Once all this rotational positioning is done, the hull and plate are marked. The next alignment is to get the plate positioned fore/aft, and port/starboard so the shaft in centered in the correct location. This is especially important in my case since my fins are being trimmed to clear the outer hull chine, and that cut is based on a presumed shaft location. If that location moves, it could cause the fins to hit the chine. That would not make for a happy day.

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ID:	26261Establishing this location is pretty easy. In the last post I showed the locator screws that go horizontally into the drill hole and provide a surface for the flange to rest against. I got bigger screws and put them in a better position, and now they catch the flange just fine, as shown in the next picture. They can be adjusted in/out to shift the flange around. I got luck and they lined up fine first try. The alignment tool is used to confirm the center location.

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ID:	26263You can see the alignment tool in the 4th picture. It's a cylinder that fits in the mounting plate bore, and has an angle iron screwed to it and cut to the length of the fin. To confirm the shaft center, you just check that the bar lines up with the fin center line and 45 deg deflection lines previously drawn on the hull. Sure enough, they do.

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The last dimension of alignment is to get the shaft exactly perpendicular with the hull. This is critical to ensure that the ends of the fin maintain proper clearance from the hull throughout their swing range and especially that they don't bind up against the hull. This alignment is accomplished using the three jacking bolts on the mounting plate. By adjusting them up and down, the plane of the plate shifts, and using the alignment tool you can tell when clearance is equal throughout the swing range. The last pictures show the tool in the centered and two extreme positions.
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Now the starboard side is ready for potting, but I think we'll get the port side ready and do them both at the same t

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Comments and discussion on this post:

u4ea32: Thanks, tanglewood, for providing this detailed information on your project. Its very interesting. Looks like you are doing all the right stuff right.

I think you did the right thing by going with larger fins. And I think you did the right thing by doing the project yourself, as those install quotes seem absurd to me too.

I know very little about stabilizers, having only used them but never installed them. However, one thing I did learn is that they work hard, and that work requires a lot of cooling. On a hard chine boat like a GB, they work very hard. In warm water such as the southern gulf stream, stabilizers can have a hard time staying cool enough. So, as in most cases of heat exchangers, I suggest you increase the cooler size over the factory recommendation.

Tanglewood: First, thanks for the comments.

I agree on the cooling. ABT wants 90 deg max water temp for cooling. In New England we are lucky if the water hits 70, but we plan to travel south at times where 80-85 deg water is likely. I get about 10 deg rise across my engines, so that means I need to grab water on the inlet side of the engines, not the outlet side. ABT normally supplies a cooler with a 2" raw water inlet/outlet, but my intake line is 2.5" so I upgraded to a 3" cooler. That also adds less inlet restriction to ensure I don't starve the main engines. I'll measure it once operational, but the calculations say I'll be well below Cummins' spec. The control panel has temp alarms, and there is a thermometer on the reservoir tank, so I'll be able to keep an eye on it.

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