OCC Forums

Speed Transducers

https://forum.oceancruisingclub.org/Topic5221.aspx

By simoncurrin - 24 Jun 2019

We have a tradition paddlewheel speed transducer which has become increasingly unreliable in recent years- it is 13 years old. For much of the time now it registers ‘0’.

I am looking to replacing it with an ultrasound sensor such as the one made by Airmar. Does anyone have any experience of these?
Simon
By Dick - 24 Jun 2019

Simon Currin - 6/24/2019
We have a tradition paddlewheel speed transducer which has become increasingly unreliable in recent years- it is 13 years old. For much of the time now it registers ‘0’.I am looking to replacing it with an ultrasound sensor such as the one made by Airmar. Does anyone have any experience of these?Simon

Hi Simon,
I am no expert, but I believe that Airmar is the go-to brand in this area. I have used Airmar transducers and paddlewheels for decades and been quite happy. They crap out occasionally, but rarely. I also think that many of the "packages" from the big name instrument makers use (or re-brand) Airmar gear in their packages.
Let us know if that fits with your researches.
My best, Dick Stevenson, s/v Alchemy
By dcaukill - 1 Jul 2019

I had an Airmar ultrasonic log the whole of our circumnavigation. The advantage of ultrasound is that it doesn't need to be raised and cleaned all the time - is maintenance free. You often learn that the  paddle wheel needs cleaning when you most need to know your speed - particularly if you have been stationary for a week or so.   The disadvantage of ultrasound is that it is very sensitive - it measures the speed of the boat as it hunts on its anchor -  even a light cross current. 0.1-0.2 knots.  If you spend a week at anchor you can easily find the boat has measured a 50-100 mile passage. Switching the depth sounder instrument display off may stop the system logging the distance - or not - depending on how it is set up.

Eventually, I gave up and fitted an Airmar paddle wheel. However, 4 years on and I am thinking of returning to the ultrasound because i am fed up with cleaning the crud off!