Re: Is there a NON THRU HULL Knotmeter?!?!
GPS will tell you your speed over the ground, which is really what you need for navigation. For boat performance (sail trim, et cetera) you need to tell your speed through the water. A paddlewheel knotmeter is, by far, the most common way of getting that info. There is at least one company that uses a thru-hull without a paddlewheel. I think it uses Doppler sonar, but it may use some other method. In any case it's VERY pricy, and you still have a thru-hull to worry about. However, there is something called a Knotstick
which is just a little towed disk, and only costs about $50. They aren't nearly as complicated (or as "shippy-looking", or as pricey) as the old Taffrail logs,
and appear to be fairly accurate, but may be somewhat of a bother to use.
svHyLyte beat me to it, and I forgot about those SpeedWatch gizmos (actually, I thought they weren't on the market anymore). But they still have something mechanical under the boat to worry about. Have you thought about just relocating the thru-hull?
Never forget them. Do something to prevent it from happening again.
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Last edited by SlowButSteady; 04-21-2012 at 11:16 AM.