Boat speed transducer for very low speed | LabJack
 

Boat speed transducer for very low speed

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Charlie
CharlieMason's picture
Boat speed transducer for very low speed

I tow a diver with my boat and would like to measure speed through water from 0 to 0.5 m/s at 0.05 resolution. I don't think I can get sufficient accuracy from gps (which would be speed over ground and also useful). I don't expect a paddle wheel transducer attached to transom to work either because low speed in rough water creates turbulence around stern. Am thinking a trailing sensor, towed sufficiently behind boat to be away from hull turbulence. I could trail a spinning device but other ideas are long tube trickling air with weight on end - slower the boat deeper the weight sinks - measure air pressure. Or tow something and measure weight of water resistance on tow rope with strain gauge.

Any ideas anyone? What's simplest thing that could work reliably? 

LabJack Support
LabJack Support's picture
I'm afraid we don't have any

I'm afraid we don't have any expertise in that specific area and have not had customers ask about this before.  I would look at techniques for measuring fluid flow:

https://www.omega.com/prodinfo/flowmeters.html

I've noticed that Amazon has flow sensors designed for low flows in coffee makers, so maybe you could adapt one of those for your application?

 

Charlie
CharlieMason's picture
No problem thanks. I've

No problem thanks. I've learned "water current sensor" to be good search term to find devices which work outside of pipe. Meanwhile I've ordered a load cell and a multiturn pot (for a string pot) and will try each to measure drag on a rope I trail behind boat. These are relatively cheap parts to try first.