[billybobs]

I have been trying for four years to stop the engine/shaft/propeller vibrations on a 48 navigator Classic motoryacht. Has anyone out there had a problem like this with these boats and have you found a solution?

Obviously, alignment has been done many times. Shaft log/strut alignment has been laser checked.

Possible considerations: wheels too big; soft engine mounts not designed for the load.

Any help greatly appreciated.

[CaptTom]

Have you tried an isolation dampner betweenthe tranny and shaft? Seen them advertised, it's a rubber mount that bolts betweenthe two. Never used one but worth considering. Also make sure the coupler on the tranny is not warped or bent.
Good luck.
Capt Tom

[ychtcptn]

It could be as simple as your props not being balanced. Have them Dynamically balanced and prop scanned to make sure they are the right shape.

While you have the props off, run the engine in gear up to speed and see if the engine is shaking (do you notice and shaking/vibration while you are running?)

I have just spent the last month correcting this problem on yacht that was run aground hard previous to my command.

[Aquaventures]

I am a broker in Ft. Lauderdale that took a 2000 Navigator 53 in trade on a larger boat. The Navigator had some vibration issues and here is what we did to correct them: Sent the props out and had them balanced. Checked and adjusted motor alignment. Removed the shafts and had them trued. Truing the shafts had the biggest impact. When we put everything back the vibration was gone and the boat ran very smooth. S&S Diesel in Ft. Lauderdale did the work.

[billybobs]

Thank you aquaventures.

[billybobs]

Interesting thought. We've run the engines up in neutral which of course tells you nothing about the driveline. Unfortunately my boat yard has an antiquated way of hauling and resplashing the boat with the props off just to run it up in gear would probably take about half a day. Maybe we can think of another way.

Originally Posted by ychtcptn

It could be as simple as your props not being balanced. Have them Dynamically balanced and prop scanned to make sure they are the right shape.

While you have the props off, run the engine in gear up to speed and see if the engine is shaking (do you notice and shaking/vibration while you are running?)

I have just spent the last month correcting this problem on yacht that was run aground hard previous to my command.

[Jamie Agnes]

I have a Navigator 48 Classic and was wondering if you
have any exhaust problems with your boat.:

[billybobs]

Originally Posted by Jamie Agnes

I have a Navigator 48 Classic and was wondering if you
have any exhaust problems with your boat.:

If, by exhaust problems, you mean sooting, the answer is yes. As I loaded the boat for cruising the original props would no longer let the engines get close to rated rpm and they were overfueling and sooting. Took two inches of pitch out of the props and that helped but not enough. Now have smaller diameter props on order and hope that cures the problem. At any rate, that will get the prop diameter correlated with the shaft diameter in accordance with ABYC specs. Factory props were too big for the shaft.