We use this on a 19ft sailing cruiser on a freshwater lake in france. The engine runs well, but when in gear and the boat has settled down to a steady cruising speed, the engine overrevs and produces no power. If you throttle down it returns to normal thrust for a while and then does it again!. The shift lever does not move, I can't make the engine do this when it is on its mooring, the boat has to be moving at a steady speed. Any ideas!!
<br /><br />You may have:<br /><br />1. A ventilating prop. Not deep enough in the water. If your vessel is pitching it may be lifting the prop to ventilating depth.<br /><br />2. A sheared prop hub that slips only when under load.<br /><br />3. A misadjusted shift linkage that is allowing the dog clutch to lose grip occasionally.<br /><br />I am inclined to think it is the prop hub.<br /><br />Good luck, and let us know what you find.