I bought a used 1994 Rinker Fiesta Vee 280 with twin 4.3LX mercs with the alpha one Gen II drives. When I sea-trialed the boat last year I did not notice this vibration but it probably was there all along. What I get is a vibration that starts at about 1500 and goes all the way up to WOT but once you get above 3500 it is hard to feel as there is so much noise and speed it covers it up.<br /> I ran the boat all this season like this and most people do not notice the vibration but some do and comment about it.<br /> Since I have pulled the boat out of the water for the season I have pulled the outdrives and the vibration is still there on the starboard side. It almost feels like an exahust pipe is grounded on a car against a floor board.<br /> You feel the vibration if you put your hands on the areas around the engine like the transom and gunells. You also feel it in the seat of your pants.<br /> The engine serial numbers are<br /><br /> Port - 0F268221<br /> Starboard - 0F268220<br /><br /> The engine runs quiet and smooth at idle and when you rev it up it is still quiet but you get this vibration.<br /><br /> The two engines are in this boat so tight it is hard to take a good look at the rear motor mounts and anything else on the back of this motor. I do notice that the front mounts for the starboard engine seem to be under some stress like the motor is trying to shift back. The port engine does not show this stress on the front mounts.<br /> I have an engine aligment tool and the alignment is dead on and the outdrive slides on and off with no effort going into the gimbal bearing or engine coupler.<br /> Could a motor mount problem cause this?<br /> Could the exhaust pipe in the back be grounded against something causing this?<br /> Any expereince or ideas on what might cause this vibration.