"The pitot tube speedometer us
"The pitot tube speedometer usually won't even move on my boat until I'm doing about 15 mph.. The best cure, is to buy a gps. even a handheld, in a bracket on the console is better than the speedo tube rig..
On the same note, if you have a lowrance handheld (ifinder..h2o etc..) there is a undocumented feature that really comes in handy as a speedometer.. With the second map up, the one that has all the optional choices below, hit the exit button three times in under two seconds, and up pops a full size speedometer.. You can vary the range with the zin zout buttons.. If you have the gps set for mph and in utilities, you set the speed threshold to 1 or 2 the speedometer can be ranged for what ever range your boat is comfortable with.. I have not seen any documentation on this feature in anything published by lowrance, but it works great, and very easy to see..Have fun!!"