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Thread: AIS and Knot Meter Requirement

  1. #11
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    Oh, gosh! Monday morning at work: But wait! I have something more important to do! Gotta look up arcane words.

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  2. #12
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    That's why I call mine a speedo - is that in there? This is also good for raising the eyebrows of newer sailors (usually followed by an eye roll).

  3. #13
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    Jackie! Where did you find that picture?!?

  4. #14
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    Quote Originally Posted by jamottep View Post
    Jackie! Where did you find that picture?!?
    This forum. 2014.

  5. #15
    Darren is offline Enough to be safely dange
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    Love where this is going. Hahaha

  6. #16
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    There are alternatives to an electronic paddle wheel installed in a hole through the hull. Go back to the 1960s...

    The knot stick:
    http://www.knotstick.com/

    A chip log and a stop watch (similar to Skip's orange, simple to make yourself):
    https://www.rmg.co.uk/collections/ob...c-object-42932

    If you really want to get fancy, there's the Walker Taffrail Log - though these were mostly used for larger ships traveling at higher speeds.

    If you want to get more modern consider a Pitot Tube or Manometer. Pitot tubes are how airplanes sense their speed through the air - about as modern as you can get.

  7. #17
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    It does feel like if the intent for the knotmeter is dead reckoning to provide position that the GPS would provide much more accuracy. Of course if the satellite network goes poof then that's that but to points stated earlier, any floating object and a watch would work.
    I'm not trying to be a smartass here, I'm certainly not a good navigator and have mostly used my cell phone's GPS, an app and downloaded NOAA charts. I'd love to be educated, in particular considering what I'm still hoping to accomplish one day. My plan is: have many GPS on board (using different networks), multiple electronic ways to see charts, and large scale paper charts.

  8. #18
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    Hi Philippe - an indirect (or direct) lightning strike to the boat is a more likely issue than the GPS constellation failing. A strike will take out the boat's on-board equipment containing integrated-circuits (IC) chips, at which point you're toast. I do carry a sextant, printed nautical almanac, HO 229, and believe it or not an analog/mechanical wrist watch - no battery inside the watch. I even know how to use it! Add some plotting paper and large scale paper charts, a pencil, straight edge, protractor - and you're good to go.

    Perhaps super-old fashioned, but that stuff does help me find out where I am when all the fancy stuff is toast. And I have a Monitor windvane - not that you'd want one of those bolted to the transom of your Class 40! Lightning squalls are no fun, lightning bolts to the water are even worse.

  9. #19
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    Good point! I forgot about the strikes. I do recall recommendations about sticking a battery-powered GPS into the oven (which of course I don't have on my boat). I wonder if an EMP pouch would work just the same.

  10. #20
    Darren is offline Enough to be safely dange
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    Quote Originally Posted by tiger beetle View Post
    Hi Philippe - an indirect (or direct) lightning strike to the boat is a more likely issue than the GPS constellation failing. A strike will take out the boat's on-board equipment containing integrated-circuits (IC) chips, at which point you're toast. I do carry a sextant, printed nautical almanac, HO 229, and believe it or not an analog/mechanical wrist watch - no battery inside the watch. I even know how to use it! Add some plotting paper and large scale paper charts, a pencil, straight edge, protractor - and you're good to go.

    Perhaps super-old fashioned, but that stuff does help me find out where I am when all the fancy stuff is toast. And I have a Monitor windvane - not that you'd want one of those bolted to the transom of your Class 40! Lightning squalls are no fun, lightning bolts to the water are even worse.
    I work with data radios and when lightening strikes it on takes out what isn't grounded. I've had things get struck by lightning and that one thing doesn't work everything is fine. I've heard you can ground the mast by wrapping chain around the upper shrouds and backstay and run the other side into the water. To be clear I'm not saying hoist your anchor chain up the mast. Just wrap it around the base. I guess you could use your anchor chain. Or if you want something else you could run 4awg wire from the shrouds and back stay into the water. The point is getting the lightning to the ocean as fast as possible. It doesn't want to go inside your boat it wants to go to the ocean floor. Another thing you should have is a polyphase on your radio coax. Typically they are grounded to earth. So I guess if you have a metal thru hull near your radio that would work. Or ground it to your mast and then ground the mast over board. There's also lightening protection "fuse" things that we use at our field radio. I'd have to look up what they are called but they work like a transistor. The high current cause an open on the load side and sends the excess current to ground, or sea for our use.

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