Broken engine mounts - prop/shaft damage?

[BrickSailor]

While Arco Iris was out of the water last winter in southern Denmark, spent considerable money on getting new engine mounts fitted. Old ones were probably original fit from 25 years ago, so I suspect a little overdue!
Had a week sailing at the end of May, during which we had some noises from the transmission. When we got back to the yard, had the engineering firm look at it who said they couldn't see anything wrong.
Came back a couple of weeks ago for our summer cruise. Several days idyllic sailing in the sunshine (sorry...) accompanied by more and different noises. Wednesday had a windless day, so ended up motoring for quite a while, passed the time by pulling up floorboards to find prop shaft visibly at an angle through the sterngland!! Anchored in a quiet bay, thought would try and get the engine somewhere close to aligned myself. Was horrified to find two mounts broken and the other two loose.
Limped into nearby marina, where we now await new mounts and the engineers to fit them.
My question is - I suspect the engineers will just fit the new mounts and leave it at that, but I think we should lift the boat and pull the propshaft to check it and the prop for damage. Am I being unnecessarily paranoid or merely sensible?
I know that being sensible goes against all my normal traits, but the image of our pride and joy sinking after the shaft has fallen out the back does concentrate the mind a bit!
Grateful for any help, and can post pictures of the offending articles if anyone's really that interested!

BS

 

[MarkJohnson12345]

Certainly no expert on these matters but I share your horror at the events your describe.

I would not move an inch (or cm) until the engine and shaft are properly lined up by a reputable pro. And damage checked for.

Would also be writing to the original engineers telling them they have a bill coming their way.

Engine alignment must be a must. The engine falling about to fall off its mounts is horrendous.

Hope you get it sorted.

 

[tillergirl]

Undo the coupling and rotate the shaft by hand. Use something like a rule to check whether its true.

 

[Topcat47]

Definitly check the stern tube, the shaft, the cutless bearing and the shaft seal before it goes back in the water. I fitted new rubber mounts to my old Volvo MD1b, only to have them "fail" within 24 hours....and I very carefully alligned the shaft after fitting so it's not necessarily the engineer's fault, although he should be liable. I don't know Danish Law on the question.

 

[Joe]

Mounts

Sounds like the wrong mounts were fitted to me
Seems very odd that 2 are broken after the last set lasted all those years
Its possible they were just fitted without any attempt to align the shaft correctly but that does sound a bit unlikely.
I also dont think the mounts would break if they had just become loose.
You dont say what engine you have but did you fit the ones recomended by the manafacturer?
Engine mounts can become loose sometimes after a new set are fitted and should be checked after a few hours use.
You can check the alignement of the shaft etc in the boat after disconecting the coupling from the gearbox
It will be fairly obvious if the shaft is bent but i would certainly have the whole lot withdrawn and checked.
Joe

 

[Neil_Y]

I would at first suspect that you had caught some debris on the prop or shaft at some point, or a blade is badly bent or broken.

This can unbalance the drive to such an extent that it can break the engine mounts (I had this happen to me) and the force of debris between bearing carrier and the prop can pull the shaft back with some force.

It's very unlikely that the engine mounts would have loosened or broken because they were badly fitted as they will have had new locknuts (I assume and easy to check)

If you have had this kind of force on the bearing carriers you will also need to look at whether the bearing carriers are still in alignment. An easy check is to chock the shaft and see if a new clearance bearing will rotate in the carrier and on the shaft.

Even if the engine mounts weren't bolted down most types will work fine as they are a cup sitting on a rubber base. For them to break or loosen something has been making the engine vibrate pretty badly and the only thing that can unbalance things is the bit hanging out the back.