SP60 issue, Looking for help with diagnosis / explanation

[Slav0]

Hi everybody,

Context:
New-to-me 30' sailboat, Beta 16, Technodrive TwinDisc SP60 saildrive (2.14 ratio). Both engine and saildrive fitted new to the boat in 2013 and very few hours (around 200).

Scenario:
While running on motor, 16hrs, saildrive seized. Engine run fine in neutral and seized when put in gear. Allowed to cool and levels checked, topped up ATF as was low. Ran on mooring for 15 mins and no noise so continued journey. 8 hours later, squeeling sound from Saildrive so knocked into neutral immediately before it seized, left to cool.

This happened on my first journey to return home with the boat. Since then, I have used the engine to get on and off the mooring but kept to a minimum and has been fine for this without any vibration or noise. However, I want to be able to rely on it when travelling further afield and decided to remove and strip this winter.

I've separated the top and bottom halves. The bottom functioning as you'd expect without any play or tight spots so I've put that to one side and focused on the top half.

Upon dismantling, bearings on each gear are fine, a very slight grumble from forwards gear but not what I would blame the fault with. When turning the input shaft by hand, in neutral and reverse is fine, in forwards gear a slight tight spot.

The bearing outer race located in the cover than may be removed is slightly loose (I can remove by hand) but no damage and wear looks normal. Again, something that needs addressing but I don't think this is the culprit.

My suspicion is drawn to the gear selector. On the one surface there looks to be some wear and some wear also on the clutch (see photos). I suspect that the squealing sound heard may have been the selector grinding on the clutch and the seize was caused by this. My theory so far is that the selector had been tightened too much (manual states tight then loosen 3/4 turn) causing excessive friction leading to expansion of the clutch / selector to the point that it no longer allowed the shaft to spin.

I have spoken with Beta and TechnoDrive, who couldn't help much based on my description. They advise me they only (rarely) really ever hear of problems requiring replacement clutch as they do wear.


Any thoughts and advice greatly appreciated.

Many thanks in advance