Prop shaft alignment: on the hard or in water?

[JOHNMARDALL]

Originally Posted by sailorboy1

While I feel alignment is of course important and would check it once in the water. I doubt all the effort to try to "get it just right" is worth it. Once the prop is turning and pushing the boat the shaft changes position and the engine mounts "give". Then there's waves, speed flex, prop fouling and balance etc etc etc.

I know I'm going aganist the grain and aren't going to fight back when the arrows come my way, but spend some time a research it.

I agree completely that even after careful engine alignment, the shaft will move sideways in the log/stern tube as the engine moves on its flexible mounts However, I still think it's worth having the alignment as good as you can get it, to minimize wear problems, up to and including the shaft rubbing against the shaft log. Installing a flexible coupling between the gearbox drive flange and the shaft flange will absorb some of that movement and reduce the consequent wear and vibration.


Best Regards
John Mardall
Vetus Maxwell Boat Equipment

[JOHNMARDALL]

Originally Posted by Rob.Lovelace

how do you maintain the seal on a PPS when doing a shaft alignment in the water?

Hello Rob,


Using the method I describe above, you don't loosen the shaft seal - the flexible hose (with PSS of the bellows type) allows the shaft to be moved back to center in the shaft log.


Best Regards
John Mardall
Vetus Maxwell Boat Equipment

[GrowleyMonster]

You can get it in the ballpark on the hard but final adjustment in the water is IMHO essential, preferably at least 24 hours after splashing the boat, with normal load of fuel, water, beer, boat bunnies, etc.

[ferrailleur]

Originally Posted by TCL

Pretty sure the answer is both. You'll do, or have the mechanic do, an initial alignment on the hard, but you definitely want to check the final alignment once it is splashed. I just replaced the transmission and while I removed the transmission, prop shaft, thrust bearing, and shaft seal, and reinstalled the transmission and shaft seal, myself, I put in a work order to have the boat yard remove and reinstall the cutlass bearing and to do the shaft alignment (after confirming that one of the guys had the requisite experience and reputation). The payment for alignment is for doing it on the yard and checking/finalizing once it is splashed. For comparison, the cutlass bearing removal/replacement was about 3 hours of labor, in part because a set screw had to be drilled out. The prop shaft alignment should happen this week. I can update with the total time if helpful.

Interesting..... Please give us an apdate… Thanks