Transmission Repair Yanmar 3YM30

[Leap of Faith 2008]

We have a 2008 Beneteau 343 with about 1200 hours on the engine/transmission. Recently the transmission has been slow to engage when hot, works fine cold. We have had oil changes per the yanmar manual, and done several cable adjustments but not fixed the problem. Oil analysis did not show any significant metals or warnings. The local dealer says there are not rebuilt units available and I'm having trouble locating rebuild parts like the cone clutch. So does any one know if I can rebuild this unit AND can I take it out while the boat is in the water? It is small and light at 20 lbs but I'm worried when I unbolt the prop shaft flange and slide the shaft aft that there will be nothing to support the shaft beyond the cutlass bearing and that this may stress the shaft seal into leaking a lot of water.

Any help will be appreciated.

 

[Philip_Oceanis 361]

What transmission is it? A ZF unit?
I had some problems with my ZF MS10-L (slipping discs, very slow to engage), first replaced the discs inside and eventually replaced the whole thing with ZF 10M (with different gearing ratio but I am chaning the prop anyway).

Anyway to answer the second question yes of course you can take it out while the boat is in the water. Unbolt the flange as you said, don't push the shaft very aft (you will hit the rudder anyway) and just place something below it to hold its weight.