Lateral prop shaft movement

[kalinowski]

I’m in the process of aligning the prop shaft after the V drive removal. Is there lateral (port to starboard) shaft movement? How much is normal? Should I assume that when the couplings are mated that the lateral (port to starboard) is centered so that I only have to consider vertical adjustments?

Thanks

Dan Kalinowski
S/V Jolly Lama (#135)
Keehi Lagoon, O’ahu

[RichCarter]

There should be no shaft movement, lateral or vertical.  If you can move the shaft in the cutless bearing it needs to be replaced.  The V-drive should have no play.  If you get alignment right, you should be able to run the engine up to at least 1000 shaft RPM, which is probably 2000 RMP on your tach without significant vibration.  This requires a shaft that is true and has no play, a properly shaped and balanced propeller, and a good coupling.   If dishes or cabinetry rattles you need to fix something.  At cruising speed, I can feel a bit of vibration in my feet if I stand near the engine but nothing rattles. 

 

If you can get things aligned in one position but they are way out of whack when you rotate the shaft, something is warped or bent.  A bent shaft is common.  You catch a line on your prop and this bends your shaft just a bit.  A line-cutter is good insurance against this.  You’ll never get it aligned with a bent shaft.  If you think your shaft is bent, bring it to a prop-shop and have the check it.

 

Another potential problem is a warped coupling.  This can happen if someone tries to remove the shaft.

 

 

Alignment must be done in the water after the boat sits for a few days after launching.  Align it for a best fit in four positions, 12:00, 3:00, 6:00 and 9:00, rotating the shaft 90 degrees four times. Back off the coupling bolts just a hair, maybe .020 in.  Slip the feeler gauges in there to measure the gap.  It should be close to the same space all the way around.  When aligned properly, you should have very little gap variation.  I think I had about .003in when I last did it.  I tried perhaps six times before I got it right.  I’d align the shaft as best I could and then take the boat out.  If it vibrated I rechecked the alignment to see if I could do better

 

 

Rich

 

 

 

[quent]

Dan

Assuming that you are still going with electric drive, it would be worthwhile to replace both the shaft bearing in the strut and the stuffing box with a drip less style one.  Not an expensive part if you are already hauled out.  Conventional stuffing box requires a small but constant drip for lubrication which doesn’t play well with electricity.

Alignment based on the electric drive instructions.

Have you considered a separate thrust bearing/ universal joint unit to take the stress off the electric motor?

Quent

[kalinowski]

Thanks for your insight Rich.  It’s great to have access to all the experience on this site!

Dan

424 Ketch #135

Keehi Lagoon, O’ahu

[Author]

Posts