Logwheel won’t spin

Posted by TitusListens@reddit | sailing | View on Reddit | 3 comments

This winter I installed a new log/ speed meter, clipper duet, in place of the one that had it’s sensor in exactly the same location, same hole. But it’s not spinning, log indicates 0, even if we’re speeding over 5 knots SOG. When I turn the sensor wheel by hand, when I’m in the water next to our (28ft) sailboat, it does indicate a speed, and it is not obstructed (anymore, there were various types of undesired underwater critters around it which I removed). But not when we’re sailing or using the engine. Any ideas what could be the issue?