Bad engine vibration B38

[icarusbop]

Hello:

On my Bavaria 38, Volvo Penta D2-55 with saildrive, took family and friends out for a pleasure sail over the weekend, we motored out fine then switched of the engine and put out the sails.
The wind promptly dropped to 0 and we had a lovely time drifting with the current for a few mins before we decided it was time to head back home.
On our way back we noticed a distinct vibration throughout the helm and hull from the engine with revs over 900RPM, I examined the engine and found it to be vibrating really badly - it looked like it was trying to shake loose form the mounts! My immediate suspicions going off the movement was a weight distribution issue on the prop (images of a lost blade with large £ signs attached to it). So we backed of the throttle and pootled home.

The day after I examined everything, then tied the boat firmly to the marina, I ran the engine in neutral up to 2K RPM, the engine was running smoothly with no excessive vibration. I then put the boat in gear and ran it up to 1.5K RPM, again no excessive vibration.

The vibration issue seems to have fixed itself, on the surface this seems positive, from the £ sign perspective, but it's not really good for confidence. Does anyone have any idea what may have cause this?

Thanks

IcarusBop

[Scorcher IV]

Icarusbob, I have had a similar experience, for me it turned out to be a load of weed wrapped around the prop that shuck the engine as though it was going to come out. We stopped put a Go-pro on a pole over the back and found out what it was the slowly reversed/unscrewed it away from the saildrive, all good once we started moving again but a shocker when it happened. £££ signs flashing before the eyes was my first reaction!

[Symphony]

Indication of something round the prop, probably weed or a plastic bag. Good prompt to fit a rope cutter as if you pick up something more substantial you will be looking at big £ signs.

[MarkTheBike]

Same here although we do have a rope cutter implying stuff was round the prop but not the leg - no idea what but putting boat in reverse and gently motoring backwards cleared it. Possibly a Kraken tentacle.