Strange noise ?????

I just pulled my boat out of storage to do an oil change, and noticed a strange sound when the motor was running. More specifically it only happens when I bring the motor back down to idle. It does not do it at idle or 2K RPM.
I sounds like low pitch squeal.
Not sure what it is...Anyone ever deal with this???}

Sounds like a belt slipping or old.

Actually, I didn't read your post right the first time. It could be a belt but that would normally happen on start up or acceleration. On deceleration at slower engine speeds it might be a bearing on a pulley or tensioner that you hear when it gets a harmonic vibration. Pull the belts and turn each one to see if there is smooth movement or excessive play. Look for shiny spots on the belts or wear while they're off.
Sorry about that.

Spray some belt dressing on the belt while running. If the noise goes away replace your serpentine belt. It's a 5 minute job.

Probably a belt or water pump.

Unfortunately it sounds like it is coming from the lower rear part of the motor...Im thinking it may be a crank bearing

I'm not a mechanic, so does this sound like its a possibility???

Hard to say without hearing it. You should take it in if you don't think it's a minor problem.

You probably won't hear a crank bearing. If it is what you will hear is a loud low knock when a rod bearing starts to go right after. Shut down immediately if you hear that. If you get a 3' piece of flexible plastic tubing you can put one end to your ear and use the other like a stethoscope to try to narrow down the spot.

What WCW says is very true.