Whining noise from gearbox

[mrybas]

Hi,
I have a newish to me catamaran that has Nani 3.21 diesels with Twin Disc Technodrive TMC 40P gear boxes. There is a loud wine coming from the gear boxes that has been there since I owned the boat. Gear box fluid (ATF) is at the appropriate level and looks good and doesn't smell burnt. Any thoughts?

[wsmac]

Run a boroscope down inside to see if you find one of these floating around...
.
.
Oh.. WAIT... did you say "Winning" or "Whining"?
Actually.. you also say you have "wine" in there too!

.
Seriously though, do you just hear the whine in a general sense or have you isolated it to a particular area of the gearbox?
.
ETA: have you spot-checked temps with an IR Thermometer?

[mrybas]

Originally Posted by wsmac

Run a boroscope down inside to see if you find one of these floating around...
.
.
Oh.. WAIT... did you say "Winning" or "Whining"?
Actually.. you also say you have "wine" in there too!

.
Seriously though, do you just hear the whine in a general sense or have you isolated it to a particular area of the gearbox?
.
ETA: have you spot-checked temps with an IR Thermometer?

Sorry, you have to pardon my poor spelling. I was in a rush to get out kiting before the wind dropped.
I haven't been able to isolate the noise to one area of the gear box...it's a pretty small gear box.

[wsmac]

I kid around alot... your spelling is fine... just taking advantage to make me think I'm funny...

Interesting no one else is commenting here... hopefully with more direct experience with this gearbox?

So from what angle are we looking at in the pic?
Top down?
Input or output end of things?

My bringing up the heat signature thing was to have one more piece to the puzzle, although a better mechanic than I might not need it.
Just wondering if you are overheating in an area that might be a bearing/bushing?

[NCboatrx]

These transmissions are not known for any noise at all if they are in good condition. You say that both are whining but you do not complain about them not working correctly, I would suggest that the transmissions are not the cause of the whine.

The way to test this is to disconnect the shaft couplings and move the shaft back just enough so that you can run the engine and transmission without turning the shaft. If the transmissions are then nice and quiet, I would suspect that the propellers are singing to you. If this is correct, then this is quite easy to fix next time the boat comes out of the water.