Can a shaft drive gearbox be removed with the yacht afloat

[Excakibur311]

So I need to remove the gearbox from my yacht which is a major bummer as she's not long gone back afloat after being out of the water for antifouling, anodes and seacock servicing.
Can I safely disconnect the propeller shaft and slide it back 6 inches ensuring the shaft does not enter the Volvo Penta Shaft Stuffing box seal to allow me to remove the gear box or is that a fast track to a major water ingress issue and a rapid sinking?
Interested to hear opinions and reasons as to why I could or as to why I definitely should not!
TIA

 

[Minerva]

No reason why not I suppose. I’d put a shaft anode on the shaft inside the hull to stop the whole shaft dropping out the back of the boat though!

 

[14K478]

No reason why not I suppose. I’d put a shaft anode on the shaft inside the hull to stop the whole shaft dropping out the back of the boat though!

This. Remember that the propeller will want to rotate in any current…

 

[MoodySabre]

You could but the prop might hit the rudder or a shaft anode might hit the p bracket preventing the shaft going back far enough. Once the box is out then support the shaft fairly true so it doesn’t affect the stuffing box.

 

[Excakibur311]

This. Remember that the propeller will want to rotate in any current

No reason why not I suppose. I’d put a shaft anode on the shaft inside the hull to stop the whole shaft dropping out the back of the boat though!

Like the anode tip!

 

[Excakibur311]

This. Remember that the propeller will want to rotate in any current…

Good point, however two pairs of mole grips could sort that issue

 

[Steve_N]

I removed the MS2B gearbox on my Storm 33 afloat some years back. I slid the shaft back a few inches and then bolted the flange to a simple softwood brace so that it could neither rotate nor wiggle about (as MoodySabre suggests) as the box was going to be away for recon for a while.

 

[Excakibur311]

You could but the prop might hit the rudder or a shaft anode might hit the p bracket preventing the shaft going back far enough. Once the box is out then support the shaft fairly true so it doesn’t affect the stuffing box.

You could but the prop might hit the rudder or a shaft anode might hit the p bracket preventing the shaft going back far enough. Once the box is out then support the shaft fairly true so it doesn’t affect the stuffing box.

There isn't a P bracket or external shaft anode the shaft emerges from the and its straight into the prop with a little anode aft of the prop.
I agree the free end would need support.

 

[pete]

If you use mole grips on the shaft protect the shaft from the mole grips teeth.

 

[PeterWright]

If you have a PSS shaft seal that will be a problem and if you have a rope cutter you need to devise a way of re- ebgaging that properly when you reconnect th shaft to the gearbox.

Peter.

 

[Excakibur311]

If you have a PSS shaft seal that will be a problem and if you have a rope cutter you need to devise a way of re- ebgaging that properly when you reconnect th shaft to the gearbox.

Peter.

No rope cutter and a Volvo type shaft seal.

 

[oldgit]

Volvo Penta 41 and MS4 reverse gear in motorboat with "P" bracket.
Propshaft to reverse gear clamp bolts removed and shaft pushed back. until touching rudder blade, about 6".
Gear box supported and bolts to engine removed.
Gearbox moved back enough to clear shaft splines from damper plate and lifted clear.
Shaft pulled back to roughly its usual position in shaft seal and secured with rope to prevent shaft dropping back,
Problem diagnosed, bits ordered and reinstalled three days later.
Job done.