I have a real bad boat vibration. It felt like I hit something. I checked the prop, and it didn't have any ding in it. The boat was idling real high that day, that the vibration happenened. I pulled up the floorboards to do some investigation. The front engine mounts very loose (the nut), I could turn with my hand. The rear arm that connects to the rudder seemed loose. I could move it up and down with my hand (is that normal) please help. Im trying to figure out was is causing the vibration.}

does it vibrate all the time or just when cruising? it could be bad carburation, and for the loose nuts, they could be the result of this vibration... or rotten stringers... vibration makes everything loose with time.

If the motor mounting nuts were loose, then the driveline would come out of alignment. That can definitely cause severe vibration and damage the wax packing on the driveshaft. Have it checked by a professional, or if you are mechanically competent get some direction on how to adjust yourself. No guarantees, but this is a very good place to start.

I chaged the packing around the driveline on a different boat before. Would that that make the difference in a severe vibration if I changed it. Also, is the arm that connects to the rudder suposed to be loose. I can move it up and down by wiggling it. I believe that it should only be able to be moved back and forth. The arm connects to the rudder via a vertical rod. The connection arm has has an ilet that slides up and down the vertical rod, it looks like it has a nut to tighten the two togeather. or is it supposed to be loose.

Get the shaft aligned and the motor bolted back down and I bet it goes away.