Unusual Bump

[Shacklepin]

I had a 5 hour flog into Tide and Headwind one day last week heading from Kemah to Galveston The chop was short and water was come over the bow as she plowed through some waves- great fun, My universal grumbled away as it always does when asked to do any work. The weather had been very as Alex had just passed through and I was concerned about debris in the water, having run across several bits of wood. The following day was a pleasurable sail into the gulf and back with the only use of the engine getting me in and out of the Marina. A day later in a flat calm another 5 hour journey lay ahead. Within half an hour of leaving the Marina there was a bang/thud from below. The engine slowed to about 500 RPM as I grabbed the gear selector to put her in neutral, she died. It sounded as though I'd either snagged a line or hit something, maybe wood as it sounded like a dull thud, but there was nothing to be seen anywhere. I went below and checked the bilges –No water coming in-, so after scratching my head I gave the prop shaft a turn, I turned it by hand and it was free in both directions. I was in the busy shipping lane and my companion cannot swim so I had to move and move quickly. I tried the starter and as always she fired up and dropped back into her grumbling normality. I eased her into forward gear which seams to snatch as it goes in but then the old three bladed prop dug in and off we went as though nothing had happened. And so it was for the next 4 ½ hours. Back nearer home waters I dropped anchor and went over the side to give the underside a look over, I found a little seaweed wrapped around the prop shaft but nothing else. I do appear to have a lot of play in both the gear box and the V drive so I can only imagine she may have jumped a gear. Is that possible Has anyone else had this happen?

[slokat]

There are no chains, belts, etc. to slip.  (in the trans/v-drive)

If RPM dropped suddenly it would seem that you were fouled on something, temporarily.

Gear slip would mean a key on a shaft, or a pin sheared... you wouldn't simply be moving again after that.

[Shacklepin]

Thanks for the reply,
I guess it must have been something like that though the water depth was good at the time being in the channel. The only other thing I could think of was a worn dog clutch. If it hadn't fully engaged it may have jumped but then why the short term engine failure? I think a gear box & V drive overhaul is due and this is a good excuse for doing it.  Thanks