Reader Tip: Fixing a Fouled Transducer

Frustrated with a fouled paddle-wheel speed transducer? Try this!

Reader Tip: Transducer

Racing off of Martha's Vineyard

Fouled Transducer Fix

On my 38-foot Sabre, I have a paddlewheel sensor with self-closing flaps that transmits boat speed to my KVH instrument system. The boat is 17 years old and for all of that time I have been fighting this system because the paddlewheel inevitably becomes fouled with shrimp, barnacles, and all sorts of minute sea creatures. To make matters worse, it is located under the bow bunks, where it is so dark it’s impossible to see what you’re doing. The boatyard that services my boat tells me that there are many other sailors with the same problem.

On every sail, the procedure has been to pull the sensor unit by undoing the split ring at one end of a pin, pulling the pin, installing the dummy sensor plug unit, replacing the pin through the dummy plug (no retaining ring needed at this point since the boat is usually stationary), cleaning the paddlewheel, and reversing the procedure. All in the dark. Total time about 25 minutes and a floor full of puddles.

This year I installed a flexible gooseneck LED light, purchased online for $6. It is attached by clamp to a semi-permanent block of wood glued under the bunk. I can now see what I am doing.

Next I purchased a fastpin that fits through either the sensor unit or the dummy unit, and eliminates the need for a retaining ring.

Now, before leaving the boat after each sail, I click on the light, pull the fastpin, replace the sensor with the dummy plug, and replace the pin. Total time = one minute or less. Before the next sail, I reverse the process. Also one minute. No cleaning, no scraping, no mess, and the paddlewheel works immediately.