Ultrasonic Logs (opinions please)

[malcp]

Does anyone have any experience or knowledge of either Raymarine or B&G Ultrasonic log sensors?

Specifically do they overcome or improve on the short comings of traditional paddlewheel logs eg

a) Require regular cleaning
b) Calibration affected by hull slime / weed buildup over the season
c) Fluctuating speed reading (measurement wander)
d) Poor linearity (actual calibration dependent on speed)

Many thanks

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[Alex_Blackwood]

Only on "Big Ships" and in general they are more accurate than paddlewheels or impellors etc. They are much less trouble to maintain. It would be wrong to say that they are not effected by marine growth etc. But not to the same extent as the others. In general you get what you pay for and I suspect that the cost is greater than that of the paddlewheel types. Try typing Electromagnetic or ultrasonic log in your search engine for more info.

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[qsiv]

Cant speak for the Raymarine option.

The B&G ones are brilliant (there are two, and they are very different beasts).

Sonic speed is the simpler and less accurate (0.1 kt), and draws less power, Ultrasonic is hyper accurate <0.1 kt, and draws nearly twice the power. Both emit pulses in a broadly similar way to paddlewheels.

They are both brilliant fit and forget- mind you race boats dont have slime, but they dont degrade because of fouling, as they measure the speed of the water flow a small distance away from the hull. Sure as h*** beats having to free up paddlewheels!

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