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Old 09-17-2018, 08:18 AM   #148
SeahorseMarineDD54201
Veteran Member
 
City: Zhuhai
Country: China
Join Date: Jun 2018
Posts: 71
Quote:
Originally Posted by twiisted71 View Post
That's what I was trying to get my head around. For a tube that diameter used as a stern tube/shaft log to bend it would have to be absurdly long. Or perhaps it was distorted during welding to the hull? But there again the only part that should be of critical alignment would be the last t8-10" where the cutlass bearing fits. The stuffing box alignment is VERY forgiving on the inboard end. The shaft:trans mating flanges not being true or the shaft being bent would be my first suspects, especially on a new build. On the far outside range of percentages it also could be a bad prop. Off center or off true bore or one or more blades not being symmetrical .

O.P. Have you pulled the prop off and spun the shaft up to see if it still vibrates/whips?
Again thanks for the words of experience (see Post #147). Based on several comments, it sounds like sag in Stern Tube is unlikely to be the cause of vibration. Seahorse workers did check during alignment and would not have proceeded if there was any observable issue with Stern Tube alignment. The shaft was pulled and checked to be straight. The Gear Box flange and the Cardan Shaft alignment was checked.

At this point I believe replacing the shaft with a name brand and re-aligning the whole drive train (as planned by Seahorse) is the way to go. Preferably there should be a vibration analysis which Seahorse has decided against.
Since Seahorse undertakes to pay for all this work done in Hong Kong now (as Seahorse does not have the money to bring the boat back to China), I will follow their decision.

Now, lets see whether Seahorse fulfills its promise, and how well Seahorse can ream the Stern Tube, without worsening the alignment due to possibly the original sag.
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