Monitoring dew point temperature at your helm, why and how

Ben Ellison

Ben Ellison

Panbo editor, publisher & chief bottlewasher from 4/2005 until 8/2018, and now pleased to have Ben Stein as a very able publisher, webmaster, and editing colleague. Please don't regard him as an "expert"; he's getting quite old and thinks that "fadiddling fumble-putz" is a more accurate description.

9 Responses

  1. Fred Murphy says:

    Loved the story. Placement of the humidity and temperature sensors is critical for accuracy. I’m thinking after end of house out of the wind induced by movement, but then again ambient wind speed effect is critical to an accurate reading. Any thoughts guys?

    • Ben Ellison Ben Ellison says:

      Thanks, Fred!

      Yacht Devices has specific recommendations about how and where to mount the YDHS in its manual. The sensor tip should be in outside air but not in direct sun or rain. Possible locations they mention are under a cockpit table or standing shelter. But there is no mention of wind.

      I haven’t yet seen Allan’s current YDHS install but I believe the sensor tip is on the back of Sally W’s faux stack but protected from rain and sun with a shield he already had, maybe from Davis. I’ll try to find out or maybe Allan will let us know. Also, Ben Stein told me that he’s getting good results with a YDHS mounted in one his engine room vents.

  2. Grant Jenkins says:

    Ben, I went through this with Maretron back in the 2012 time frame – I still have the screenshots from N2K Analyzer showing the WSO100 outputting PGN 130313 with zero and blank fields in the humidity fields. Maretron at the time refused to swap it out under warranty, and insisted we send it for repair. It came back with the humidity sensor replaced and working, but the air temperature needed to be offset almost 35% to read accurately! The humidity sensor failed again the following year, and the next time we tried to have it repaired, they weren’t even fixing them anymore and discontinued the product. I thought by now they would have come up with a reliable replacement, but apparently they’ve ceded that market to Airmar. Very disappointing…

    • Ben Ellison Ben Ellison says:

      Sorry to hear that, Grant, but have also heard rumors of failing humidity sensors in Airmar WX devices. Maybe that’s why they made the sensor optional in more recent models and also replaceable in the field. Were you hoping to have dew point temp on your boat and, if so, did you get it somehow?

      • Grant Jenkins says:

        Actually it was another guys boat, and he would have been happy to just get humidity displayed – but at the time the Airmar replacement was north of 1K and he decided he didn’t need it that bad. Personally I love the idea of dew-point temperature, especially if you can read it to one decimal place – as shown in your article. I’m glad the sensors are now field-replaceable, that’s a big help!

  3. Christopher says:

    I use a YD sensor, I printed the casing on a 3D printer, it has been working for 2 years without any problems outside the yacht.
    I have photos but it is not possible to attach to the answer.

  4. Christopher says:

    Yes the dew point is very handy, I saw the temperatures level out on a Sunday night and I got foggy in the early morning as I sailed out into the bay.
    I showed the project last year, Aleksandr from YD ;-).

  5. Larry Olson says:

    Good article and great info. I’ve been holding back on a weather station because the cheap ones are just not that accurate and where I boat (ICW and Loop) weather is easy to get. But would like one, especially with the temp/due point and wind, corrected with boat speed. So, I’m following this.
    And, temp/due point is a great tool, but not an absolute. Fog can form with a spread and may not form if they are the same… lots of other factors.
    And there’s fog… and there’s fog where you have a hard time seeing your hand, which is something that most of us would most likely avoid. And, how wide spread is the fog? However, there’s an argument to get all the info you can to deal with fog.

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