Navigator Vibrations

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

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.

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.

Navigator

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

I am a surveyor in the SF Bay area. I just went on a seatrail today and found the top exhaust on the port side was running much warmer then the starboard side. but only after the Y. And only below 1500 RPM's, engine speeds higher then that the fiberglass exhaust Y and hose would cool down to equalize with the lower. Other then that the engine ran Volvo ran flawless and all other temps and pressures were normal.Has anybody come across this or had issues with this?

You really don't want to reduce prop diameter. Who took 2 inches of pitch out of the props, were they dynamically balanced? I'd take the boat out and leave 1 engine in neutral, put the other up to 1000 rpms, then say 1800 rpms or near cruise and see if there's a vibration, also note how many rpms each one turns (only for a minute) see if one side has vibration and not the other or one engine is not making rpms

Agree. At higher hull speed your scoop strainers are pushing water through the raw water system regardless of condition of your impellers. This could just be a warning sign.

What is your issue other than a difference in exhaust temps in your data?
Does the exhaust system show any abnormal wear and how many hours on each engine?
One engine is a direct dump to the outboard exhaust tubes and the other is routed from centerline to outboard, which one has the higher temp?

What year is your Gator?
Some of the 2005-2009 boats had undersized engine mount bolts.
A friend of mine had a couple break! Bit of a vibration there!
If your mount bolts are defective (stretched?), maybe the engine is doing some vibration at higher rpms.
I'm sure that you looked at them at speed with ear muffs, eh?