Quote:
Originally Posted by chris95040
Thanks for all the input, everyone.
Can anyone comment on the accuracy and precision of a paddle wheel based STW vs other techniques (ultrasound?)?
Anyone know how the ultrasonic ones work (as in, how they arrive at a figure)? I can't really think of how you'd do it, other than some crazy machine vision feature-detection that they are certainly not bundling into those sensors.
(EDIT: I just read that they work by "tracking particles in the water." Huh. Are these things giving you reliable readings? Do they suck in cloudy water? Or do they suck in crystal clear water?)
Also it looks like B&G offers "remanufactured" MFDs at a significant savings. Curious if anyone's had any luck, or any horror stories, going that route. |
Chris--
Once calibrated, we found our Standard Horizon SL150 to be very accurate, I believe within a few percents of actual/true STW. I expect the B&G speedo will be as well. Calibration is not that difficult on a calm day. We used both the time/distance method between known points, up
current and down; and, with a "KnotStick" suspended off our transom to verify. I'm sure the "Ultrasonic" speedo's are no less accurate if not more so but I'm not sure the additional cost is merited given how easily I can withdraw and clean the paddle wheel, which only takes a few minutes, on our
boat. (In our case, we have very easy access to the speedo
transducer.)
B&G does sell "remanufactured" devices through its own outlet store at a fair discount to the MSRP. They are
sold with the same guaranty as "new"
equipment (according to B&G's web-site) and so should be no less reliable. You will want to compare B&G's prices with prices for new at other vendors such as Defender, however, as Defender has very favorable pricing itself. (Include tax and
shipping costs in your comparison, however.)
FWIW...
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