After spending a good amount of time over at the boat yesterday checking the prop shaft, here's what I found.
Pulled the stuffing box forward and here's what it looks like. Seems fairly centered to me. How else would one adjust that except with boat being out of the water? It would seem theoretically that the rubber bushing in the cutlass bearing would allow some minor self alignment of the shaft between the prop and the front end as long as the shaft was fairly well centered in the shaft log.
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All shaft alignment is dealt with at the thrust bearing. Allowable misalignment between engine and thrust bearing can be up to 8 degrees side to side and/or up and down. The only adjustments deal with the rubber bushings where the thrust bearing carrier attaches to the mounting frame. And that consists mostly of tightening the bolts to compress the rubber bushings to 15mm clearance between bearing carrier & mounting frame. And those bushings show no signs of deterioration. Otherwise shimming the mounting frame up, down, or sideways. Those bolts holding the bearing carrier go though holes in the mounting frame, and thay are not slots that allow any shifting. So we'll see next time we take the boat out. Otherwise the only other cause of the wobble is likely to be with the cutlass bearing, the most likely suspect being that rubber bushing on the outside of the bronze tube. I have a 1 inch micrometer that I can use to measure the shaft and tell if it's 1 inch or 25mm, and if we're still having this wobble problem will go ahead and order a new cutlass bearing from Albin.
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I looked through all the receipts & documentation that was passed along from previous owners, and found no mention of a new shaft ever being installed. Doesn't mean there was one, but unlikely that such receipts wouldn't be saved along with everything else. From the looks of Frank's old AD21 installation it may be that a new shaft was not necessary. One note of interest was that the Yanmar was installed four years before the AquaDrive was added in 1990, and the receipt for that said the price of the AquaDrive unit was $358. Be nice if those prices were still available. So either a)there was a new shaft for the straight connection to the Yanmar that later had to be shortened, or b) the engine was mounted further aft then moved forward to accommodate the AquaDrive, or c) shaft was replaced a 2nd time when the AquaDrive was added.
Whatever the case, the brochure for the Yanmar claims the 3GM30F engine runs much quieter and less vibration than older generation engines, and the AquaDrive brochure claims a 40% reduction in noise and vibration due to the engine being isolated on soft mounts and being allowed to flex by the CV joint, plus all the propeller thrust being absorbed by the thrust bearing. I believe that, especially after getting a ride on Sunsetrider's boat. The difference in noise and vibration was shocking, as our boat is not much louder at 2,300 RPM than riding in a car, and is virtually vibration free. The prop we run is 16.5 X 12, and stamped "JAX FL".
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