Ultrasonic speed sensor. Any good?

[runningman]

Have you considered buying one in the USA? These people http://www.p2marine.com/marine-electronics/airmar/airmar-cs4500-speed-transducer.shtml are selling them for less than £450.00 even at today's poor exchange rate. Even with a bit of delivery and VAT its got to be cheaper than the prices you have been quoted

Yes I considered buying in the US, but, the VAT is £90 + say £30 delivery, + the NMEA converter (quoted £292 + vat in UK) required to talk to my instruments. Add it all up and there still won't be much change out of 1k.

 

[johnalison]

As it happens, I have an as yet unopened can of Trilux 33...

A little silicone grease is all that mine gets. I scarcely ever have to clean it until the end of the season when is gets creepy-crawlies from the adjacent hull.

 

[Bobc]

I've not had a working log for 5 years now, and don't miss it.

Just put the blanking plug in and forget it.

 

[mainsail1]

I gave up on an impeller log a couple of years ago, shortly after foolishly thinking a replacement would solve my problems. I cannot understand why the manufacturers have not moved on from this useless, out of date, technology. I now use SOG instead ,however, I would prefer to know my speed through the water if it was economically possible. At present that does not seem to be feasible with an ultrasonic speed sensor.

 

[Jonas]

 

[Woodlouse]

Most paddlewheel logs are easily removed when fitted to a modern boat so there is littl excuse for leaving it in place all year to foul up.

As for ultrasonic sensors, I've been around many raceboats with bottomless budgets and they all use paddle wheels. I can only conclude that paddle wheels are more accurate when calibrated correctly.

 

[maby]

Let's look back at the problem.

What is my speed through the water?

And then ask do I really need to know it?

I like to have both speed through the water and speed over ground in order to be able to estimate the current. Also, when my paddle log last jammed up, I was unable to work out how to get the wind instruments to use SoG instead to calculate true wind - that may have been my shortcoming in reading the manuals!

 

[RichardS]

I like to have both speed through the water and speed over ground in order to be able to estimate the current. Also, when my paddle log last jammed up, I was unable to work out how to get the wind instruments to use SoG instead to calculate true wind - that may have been my shortcoming in reading the manuals!

See http://www.ybw.com/forums/showthrea...ymarine-ST60-and-ST60-Tridata-instrumentation for the most likely reason for your lack of True Wind ..... and the only solution. I'll be reporting in due course on whether it works!

Richard

 

[Woodlouse]

I like to have both speed through the water and speed over ground in order to be able to estimate the current. Also, when my paddle log last jammed up, I was unable to work out how to get the wind instruments to use SoG instead to calculate true wind - that may have been my shortcoming in reading the manuals!

See if there is an option in the system for ground wind. That'll use the SOG and COG to calculate.

 

[maby]

See if there is an option in the system for ground wind. That'll use the SOG and COG to calculate.

I have looked and there is an option for ground wind, but it seems to be very restrictive. True and Apparent Wind give me the nice traditional display with the heading always at the top of the screen, the wind angle shown as a needle round a circular dial and the wind speed in knots at the bottom. Ground Wind just gives me the numeric compass bearing of the wind calculated with reference to the GPS rather than the boat speed.

 

[RLMM]

I'm looking for a B&G Ultrasonic speed transducer. The whole piece is about 9" long and includes the 2 sensors. I'm hoping someone has a spare tucked away in their locker. Email me directly, slowasmolasses@hotmail.com

 

[greeny]

Plan B and part of plan C.
Use the log until it stops and then use gps until you clean the log.

 

[chriss999]

NASA Marine are working on their new version. I don’t know when it will be available; but it should be cheap.
https://www.nasamarine.com/product/electromagnetic-log/

 

[Porthandbuoy]

I fitted one of Cruzpros paddle wheel pulse to nmea converters. Works great. SOG on a bog standard NASA speed/depth display.

http://www.cruzpro.com/gps2.html

http://www.cruzpro.com/sog2.html

http://www.cruzpro.com/sog1.html

 

[maxi77]

I gave up on an impeller log a couple of years ago, shortly after foolishly thinking a replacement would solve my problems. I cannot understand why the manufacturers have not moved on from this useless, out of date, technology. I now use SOG instead ,however, I would prefer to know my speed through the water if it was economically possible. At present that does not seem to be feasible with an ultrasonic speed sensor.

Commercial doppler logs usually have both water and bottom lock

 

[snowleopard]

I presume you are looking at doppler logs. The big problem is they use rather expensive technology compared to a paddlewheel. Very many years ago NASA produced one but it had little success.

I put one of those on a boat I built in the mid-70s. Under normal circumstances it worked well but when the wind stopped and speed fell to under 1/2 knot it went berserk, showing speeds of 20kt+. I had to switch it off so I had sensible figures on the odometer for my DR (pre-GPS days of course). I never did figure out why it would do that.