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As a follow up to my post about fuel gauge senders, I ultimately determined that the issue lies with the gauge at the helm, not the sender itself.

A seldom discussed benefit of catamarans is that most often we have two of each mechanical item, allowing us to swap one for another during troubleshooting exercises. I have found this to be extremely helpful. In this case, after ruling out the senders as the source of the trouble, I simply swapped the gauges. Voila! Now the port side tank reads full, as it should.

Testing the sender with a multimeter.

Quick clip recorded on our iPhone.

In our particular case, until we get a replacement gauge, it’s more important that I have the proper reading for the port tank than the starboard one as it feeds both the engine and the generator. Because of that, it always goes down faster than the starboard tank.

A bit of advice for anyone shopping for a replacement gauge: make sure that the resistance rating of the gauge matches that of the sender. While I found VDO brand gauges in stock here on the island, none of them properly matched the ones on the boat.


  1. Thank you Mike for the journey of this repair. I have been following intently as I have two non-functioning fuel gauges. VDO brand as well. So your last comment was icing on the cake. Now to trouble shoot mine!! ( hey coming to Caneel bay? Lol)

    Fred and Phyllis

    Lady J 111

    • I would have been happy to get my hands dirty with you but sorry, we will not be coming there. We have charter guests that we are picking up here in St. Thomas on Wednesday. I’m sure you can do it though. The hardest part is getting the sender out of the little hole in the top of the fuel tank. You just have to play around with it a bit until you can line it up just right. My understanding is that the problem almost always lies with the sender. It just turned out that that was not the issue in our case.

  2. The heading of this post highlights an advantage of a cat. I am looking at getting a secondhand cat in the coming year, which I blame the following of this blog entirely for that decision 🙂
    Your maintenance stories are always of interest. As you and Rebecca have been on this and you PDQ for quite some time, what areas of the vessel do you think need to be checked that go beyond what the marine survey? The survey will have limitations, and it is only after being on the vessel for a while that you would discover the other small issues.
    What would you check for next time in addition to the survey?

    • I think the ideal is to have a good surveyor who has experience with the particular type of vessel (brand, model) that you are looking to purchase. That way he/she will know what issues are common and be looking for them. Even in the case of One Love, where we had a very thorough survey, a few things were missed. Could they have been found? Sure, but I don’t blame the surveyor. Many things do not become apparent until you’re on the boat and operating it. Fortunately for us, we were able to take One Love on a week-long sea trial and the Moorings repaired/replaced everything that we found amiss during that week, even if it was not noted in the survey and/or CAOV (conditional acceptance of vessel) list. Yes, the Moorings looked after us well!

  3. Hi Mike, a question…
    My fuel gauges, VDO’s are installed at the helm in a removable panel. Once I remove the screws holding the panel everything still stays in place. How are these gauges attached? The gauges have flange outside the panel. However, not wanting to break them, can you tell me the attachment method??

    Thanks Mike

    Lady J 111

    • Disconnect the wires. Then, holding onto the front of the gauge as best you can, twist the back of the gauge in a counter-clockwise direction. It is like a large white plastic “nut” fitting over the gauge. Unscrew that piece and you’ll be able to remove the gauge from the front of the panel.

  4. Ahh, thanks Mike…
    This is in the hatch head first type of job…sigh


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