Pulling and Cleaning our Airmar Transducer


Last Updated on August 7, 2020 by Amy

Down in the bilge, in the forward guest cabin on our boat, is a hole! Normally, holes in boats aren’t a good thing, but this is one of those rare exceptions. In this hole is the Airmar Transducer that is part of our navigation equipment system.

Proper Care of the Transducer

One day, we noticed that our True Wind Speed and Apparent Wind Speed were equal, even when we are underway. That shouldn’t be happening. We did some investigating and learned that our new boat has something called a transducer in it.

The transducer has a paddlewheel and a sensor on it. The paddlewheel tells us our speed through the water, which is used in all sorts of calculations by our navigation equipment. The sensor tells us depth underneath our keels and water temperature.

For the AWS and TWS to be reading equal, it meant that our boat speed was not reading correctly. We needed to pull the transducer and clean the paddlewheel to get it up and running again.

In an ideal world, every time Starry Horizons was stationary we would remember to pull the transducer and replace it with the blanking plug. But, that doesn’t always happen. Instead, we find that our paddlewheel is junked up, so we have to pull the plug and clean it.

Pulling the plug is not for the faint of heart! Remember, we’re really just opening up that hole in our boat, which is a bit intense.

Our transducer has a self-closing valve that prevents too much water from coming in, so we only get an inch or two in the small compartment. When you pull the transducer, you want to have that blanking plug very handy to pop right in.

Supplies to Clean the Airmar Transducer

Our transducer is an Airmar Smart Tri Multisensor DST800.

  • The Absorber (or other chamois)
  • Vaseline
  • TruPlug (just in case)
  • Blanking Plug – should come with your transducer
  • Pocket knife
  • Cleaning supplies

Steps to Pull and Clean Your Transducer

  • Plug any holes in your bilge walls to prevent water from flowing between compartments. I use The Absorbers for plugging the holes.
  • Lubricate the blanking plug O-rings with vaseline.
  • Unscrew the cap nut of the transducer. It takes A LOT more unscrewing than I expect every time, even though the cap screw feels loose. Try wiggling the transducer.
  • When it pops out, quickly place the blanking plug in the thruhull.
  • Inspect the transducer. It often has shellfish growing in the paddlewheel. Test the paddlewheel to make sure it is freely turning.
  • Lubricate the O-rings on the transducer.
  • Remove the blanking plug, and pop the transducer back in. Make sure the transducer is facing in the right direction (there’s an arrow).
  • Clean up your mess!

Watch the Video: Cleaning Airmar Transducer


  1. Thanks for the tips! Proper care of the transducer is paramount for accurate readings and safe navigation. It’s fascinating how such a small component like the paddlewheel can have such a significant impact on readings like true wind speed and apparent wind speed. Regular maintenance, like cleaning the paddlewheel, ensures that our navigation equipment functions optimally, preventing discrepancies in readings and potential hazards at sea.

  2. What are the epoxy discs you used to attach the solenoid to the fiberglass? I’m going google crazy here and can’t find them yet.

  3. Great videos! These are really very helpful – THANK YOU BOTH.

    Was a decision made not to choose the freshwater flush marine toilet option ($1500) from the dealer and DIY? If so, I imagine you saved $$.
    They also offer a “fresh water flush” option for $500 so I will have to figure out which option to go.

    Petroleum based products on rubber is to be avoided as a rule,unless you have nitrile then your ok. As often as you’ll have to clean it, it should be fine. Use a silicone grease next time and Do you have spare O-rings?

    ps: I jumped as well when the water rushed up! 🙂

    1. Hi Jon, non related questions are just fine. 🙂 Our primary heads are electric with macerators (we have one manual head in case all other electrical systems fail) and we read the instructions quite carefully and it said there is no problem for toilet paper to go down the head. We are rather careful to limit just how much toilet paper goes down in one flush though.

  4. Good video very educational. They certainly have improved on transducer design as many require boat to be hauled.
    When I’ve dealt with O rings, the lubricant used is specifically made for rubber O rings, with a warning not to use Vasoline as it is petroleum based and can damage O rings. Your transducer’s O rings may be made of some other material not effected by Vasoline.
    I was surprised there was not more water pressure coming thru the hole and that you ended with less than a qt of water in bilge.

    1. Hey Doug, we were curious about that too. Our instructions do say you can use Vaseline by name, so that’s good, however it works! I was surprised too by how little water came in. Thankfully.

  5. We use CLR. Put a few ounces in a deep cup, put transducer in so bottom is totally immersed in the CLR. Soak for 30 min, and it will be whistle clean. Product dissolves calcium, lime and rust, and in FL the paddle wheel gets gummed up a lot.

  6. Well done Amy! Despite having Garmin instruments instead of your Raymarine’s, we have exactly the same transducer. As our boat is in an area of very fast marine growth, I take the transducer out and replace it by the plug every time the boat will be still for more than some days.
    We are still following you around. Fair winds!

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