Prop shaft alignment

One of the things the per-purchase survey turned up was play in one of the prop shafts and to replace the cutlass bearings. After removing the shaft and installing the new bearing, we found the root of the problem was the shaft was out of alignment – the shaft was over an inch away from reentering the stuffing box. Either the strut was bent, or maybe it had never been in alignment to begin with as there was no viable damage to the strut.

When we unbolted one end of the aft strut it “snapped” to its desired position, which was about an inch from the hull and aft about an inch.  The forward strut was fine. With the strut loose, we inserted the shaft, got everything lined up and supported, then created new pads for the strut.

New strut padOn the strut that attaches to the keel, we were able to use the original holes, but it did not fit flush to the keel at the top. The support that goes through the hull was a different story – it was not in contact with the hull at all. We filled in the “gap” for both with a glass/resin mixture.  In the picture, it almost looks like there is plywood above the strut, but that is just the glass on the duct tape used so the glass would not stick to the strut. My finger is pointing to how far out of alignment it was.

After letting the glass cure, we got new bolts an inch or so longer (they were cheap) and drilled new holes through the backing plate.  Once completed, the adjusted shaft turned better than to other side.

One Comment:

  1. I just changed my cutlass bearing and when I went to slide the shaft back in, I had to push the end of the shaft up while someone hammered the shaft through the log. Obviously, the shaft rests on the bottom of the log shaft and if centered in the shaft it has tension. I can visually see the shaft is high on front of cutlass and low on rear. Can i just loosen the bolts on the rear until it aligns and stuff it with cathair? Is there much chance of a significant change when in the water versus trailer?

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