Engine / Prop shaft alignment advice please

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malcp

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During changing my cutlass bearing and stern gland I've found a small amount of misalignment (0.2mm) between the engine coupling and propshaft collet on my VP2030 (35' sailing yacht with 25mm shaft drive, with tube / shaft log, not P-bracket). Stern gland is VP's rubber seal (slight wear on lower side of internal bearing, but no leaks).

The Volvo manual says the alignment should be better than 0.1mm. Has anyone got any advice as to the best way to go about this?

The misalignment is in 2 dimensions; feeler gauge showed gap on port hand side of coupling and underneath.

Thanks in advance.
 
You will have to move the engine to reduce the misalignment to the minimum. I would shift the engine sideways first, you may have to 'twist' it to get it correct, then lower the aft end. Usually the engine will be on 4 adjustable, up & down & left & right mounts. You will probably have to use a jemmy to do the actual moving. The mounts often ahve slotted holes for sideways movement. If you cannot adjust out the misalignment, you may be able to fit another coupling to the engine which will allow for misalignment
 
Thats basically correct. You can achieve rough sideways alignment by slackening off the hold down screws on the engine feet and levering the engine sideways. Once you have achieved this screw the mounting feet firmly down to the bearers and jack up the feet to move both forward and aft pairs of mounts up and down as required.
You also have the opportunity if you are already within such a close limit to move the engine sideways by jacking up both of one side and jacking down both of the other side which will move the engine drive shaft flange port or starb'd. Mark the present position of the screws before you start and you will always be able to return to the original position. Hope this helps
 
Wait until the boat is afloat before you set it up.

You may well find the misalignment is due to the hull being ashore and having flexed slightly, and that it will go back once she is afloat again. It will have to be rechecked afloat anyway with the new gland and bearings..
 
If you have a gap on the lower side of the flange then you will need to lower the FRONT of the engine NOT the aft to close it up.
 
Further to Oldharry's comment the rigging tension with the mast fitted will also distort the boat so best wait until it is ready to sail before worrying about alignment. olewill
 
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