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Different shaft rotational resistance

Posted: April 17th, 2021, 9:43 pm
by Superg
The port prop shaft in my 1985 3207 with crusader 270s offers more resistance to turning than the starboard shaft. The starboard shaft rotates quite easily by hand whereas the port shaft has noticably more resistance to it. Not crazy, but is definitely noticeable.

The marina mechanic said my starboard side cutlass bearing could use replacing. There isn't much movement in my opinion to warrant replacing yet, but in any case, that is the side that turns more easily, which doesn't make sense to me.

Could it be something in the port engine or transmission that is causing greater resistance?

Re: Different shaft rotational resistance

Posted: April 18th, 2021, 10:22 am
by Viper
Before one jumps to any conclusions, the strut bearings must be wet when turning the shafts (a practice often ignored when checking). This lubricates the mating surfaces so there is minimal friction between the rubber and steel. A shaft usually turns easier in a worn bearing due to less surface contact providing everything is aligned properly. On that note, the one that is more difficult to turn may not be properly aligned. The transmission or engine would be the last thing to consider. Also consider that on land, your hull may warp a bit on blocks which can throw your alignment off, hence the need to allow the hull to rest in the water for 24-48 hours prior to doing a final alignment at the coupler. Because final alignment is done in the water, the best you can do on the outside while blocked, is to ensure the strut is reasonably aligned with the shaft tube through the hull, this is best done with the coupler disconnected from the tranny so that it's not influenced by the position of the engine. If the strut to tube alignment is within reason on blocks, if it changes a bit once the hull rests in the water, there should be room for the final alignment of the engine.

Re: Different shaft rotational resistance

Posted: April 18th, 2021, 10:50 am
by Superg
Most excelllent. Thank you!
Given that I've not had the alignment checked since purchasing the boat four years ago, I will put it on the list for the marina to do this season once it has sat in the water.

Re: Different shaft rotational resistance

Posted: April 18th, 2021, 12:39 pm
by bud37
To add...inspect how the shaft is centered in the strut bearing as well.....you can see off center wear, if it is present the bearing material will be worn more on one side or the other, or up and down. As viper said when the boat is blocked , depending on the blocking skills of the yard , you have to be careful drawing conclusions from just one thing. Boats flex a fair bit, more than one would think.

Re: Different shaft rotational resistance

Posted: April 29th, 2021, 12:35 am
by Superg
Looks centered, thank you. Spoke with mechanic, and he thought it is not enough of an issue to warrant addressing, and that I would definitely feel a vibration if something was out of alignment. That said, once the lake warms up, I'm going to dive in on a clear day and try rotating them by hand with the boat in the water.