Damaged something underwater where to start

"I have a 318 with a 1:1 velve

"I have a 318 with a 1:1 velvet Drive transmission. I put in a new prop shaft 4 years ago, and had the prop reconditioned back to class A specs. I haven't hit anything since then... until today.
I was cruising this afternoon at about 2900 RPM (~ 12 knots) and didn't see a lobster buoy in my path. The engine skipped a beat, the boat hesitated slightly, then continued running at the same speed. I looked back and saw a buoy in the middle of my wake. I throttled back and didn't perceive any noticeable vibration as I continued along, so I gradually brought her back up to speed and continued on about another 20 minutes to Quonset Pt. where I idled around (in fwd or neutral) watching the Blue Angels perform at the RI Air show (great performance!). At some low speeds, (1000 - 1400 rpm) I thought the transmission sounded funny. Not a grinding, not a clunking, I would describe it as a whir at certain RPMs that I wasn't there before. When I increased or decreased speed slightly the sound would disappear. The trip back to my mooring was almost an hour. I ran at about the same speed (2600 - 2900 rpm). During that run, everything seemed OK, until I arrived at my mooring and engaged reverse for the first time. I got a distinct clunking (thump, thump, thump at the engine rpm) from the area of the stuffing box/transmission. I wasn't able to locate the precise source of the sound. When I was on the mooring, I tried reversing the engine a few times, and each time when I went into reverse, I got the clunk which then also occurred in forward. I only engaged forward or reverse for a couple of seconds while on the mooring. I must have damaged something - shaft, prop, strut, transmission?

My question is where to begin figuring out what needs to be fixed? There is nothing there that I haven't worked on before, but I'm not sure how to figure out where the problem is. I'm thinking about starting with an inspection dive to see if there is any visible damage, but if the shaft or prop are slightly bent, I don't expect to be able to detect that visually.

If something were dramatically bent, I think the vibration underway would have been more significant.

Unfortunately, I think this will require hauling the boat. What do you think?"

"I'll bet you wrapped a li

"I'll bet you wrapped a line around the shaft and it's cut off water to your cutlass bearing (the rubber deal in the strut). If so, it will burn up in short order and allow the shaft to whip around.

Suggest diving in and taking a look. If the line is gone, try moving the shaft sideways. If you feel ANY sideways motion the rubber bushing has to be replaced (or you'll tear up a bunch of parts).

Jeff"

"Jeff, as usual, you nailed it

"Jeff, as usual, you nailed it. I took a dive this afternoon. I had about a foot of rope wrapped around the shaft. I was able to clear it easily. When I reversed the engine, the loose end of the rope is what produced the thump, thump sound.

The cutlass bearing is now toast. There is no rubber left. I'm sure that the metal on metal of the shaft in the cutlass bearing sleeve produced the whirring sound that developed shortly after I hit the buoy. After hitting the buoy yesterday, it sounded fine until the rubber in the cutlass bearing burnt up.

Back topside, I disconnected the shaft coupling from the transmission and loosening up the stuffing box a little, I was able to slide the shaft back about 3 inches. I went back in the water, to see how the shaft looked where it was rubbing on the metal sleeve of the cutlass bearing. Fortunately, the hardened stainless shaft didn't appear to have any ill effects because the cutlass bearing sleeve is soft brass. I couldn't see or feel any imperfection on the shaft, where it was inside the cutlass bearing.

I ran the engine in both forward and reverse with the shaft coupling disconnected. The transmission sounds fine.

I'm pretty much resigned that I'm going to have to haul the boat to replace the cutlass bearing, but I feel a little better, now that I think the scope of my issue is clearer.

Of course it doesn't make be happy to know that I missed two chances to avoid this expense by a) paying closer attention to avoid lobster buoys, and b) by making sure the prop was clear before getting back underway.

Thanks!
Chuck

PS. Even with my shorty wetsuit, 63 degree water is chilly!"

"Brrrrtr! alright. What happ

"Brrrrtr! alright. What happened to Spring?

Jeff

Postscript to those of you who experience this problem: If in doubt, back up! That's right. Don't have to go over the side in freezing water with a knife in your teeth like a pirate. Whack it good in reverse, then eeeaaase away in forward. That often unwraps what's wrapped around your prop/ prop shaft."