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Plotter depth warning?

Discussion in 'Technical Discussion' started by Pelagic Dreams, Nov 15, 2011.

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  1. Pelagic Dreams, Nov 15, 2011
    #1
    Pelagic Dreams

    Pelagic Dreams Senior Member

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    This might sound really stupid....or uninformed....but if you are running with your plotter on, with a current nautical database, why would the plotter not warn you of entering water too shallow for saftey? It knows your position via GPS, knows the water you are in and sees potential areas of danger ahead of your current heading.
    I guess I am sort of seeing it as like a phone app of navigation...."Leaving the channel boundries....come starboard 4 degrees....." "Shallow reef ahead, 1000 meters.....come port 10 degrees' Am I dreaming or is this a viable technology? It would seem to lessen the chances of grounding during both day and esp during night passages.

    Don't laugh at me too hard, just educate me......
  2. tirekicker11, Nov 16, 2011
    #2
    tirekicker11

    tirekicker11 Senior Member

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    The Navionics chart plotter app on my android does have this function.
  3. sharkbait, Nov 16, 2011
    #3
    sharkbait

    sharkbait New Member

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    is that program stored in full on the phone or is on the server?

    what is the range of use in your area/country?

    im just curious.
  4. tirekicker11, Nov 16, 2011
    #4
    tirekicker11

    tirekicker11 Senior Member

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    it's an app I bought from Navionics trough the app store. It's stored on my phone's memory card and uses the internal GPS antenna. I bought the SE Asia charts because that's where I use it. The detail is great and I have used the phone plotter as a primary when delivering yachts in coastal/familiar area.

    For longer passages and in unfamiliar territory I'd prefer to use a larger screen as primary. Maybe Ipad or android based tablet. I've paid the equivalent of a single paper chart for this app.

    I believe these Navionic apps are discussed here before.
  5. Pascal, Nov 16, 2011
    #5
    Pascal

    Pascal Senior Member

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    Not sure I see the benefits in the real world. In many areas, Chart soundings are not accurate enough to really rely on that only for safe navigation when you get in areas where you have to worry about depths.

    But most importantly it s the skippers job to pay attention, plan a route and follow it, check actual depths, etc... If someone doesn't see a reef on their plotter, may be they should not be at the helm.

    And you already have shallow alarms on depth sounder...
  6. dennismc, Nov 16, 2011
    #6
    dennismc

    dennismc Senior Member

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    Plotters

    Try it in the ICW in Florida Bay after a Nor Wester has been blowing for 3 days, you are liable to be on the bottom and the plotter still showing nav depth.
  7. luckylg, Nov 16, 2011
    #7
    luckylg

    luckylg New Member

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    Bottoms change. Charts are, more or less, static. Oh, they get updated, but not nearly as often as the bottom does. A depth alarm is more often and more appropriately on the fathometer since it's measuring real world status.
  8. Capt J, Nov 16, 2011
    #8
    Capt J

    Capt J Senior Member

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    This, as well as the plotter had no idea what your depth needs are or navigation needs. Also the plotters don't have the CPU speed to do all of those functions.
  9. NYCAP123, Nov 16, 2011
    #9
    NYCAP123

    NYCAP123 Senior Member

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    Plotters only tell you what should be. Your radar, depth finder and eyes tell you what is. Plus charts are only as good as the person who draws them. I have yet to find one that doesn't show me running across land in one small canal or another, even when it shows accuracy to 7 feet. It's just a tool.
  10. Pelagic Dreams, Nov 16, 2011
    #10
    Pelagic Dreams

    Pelagic Dreams Senior Member

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    that was my first idea of a problem with the idea....how current the chart is the Nav system is following.
    I agree with you all in the terms that the capt. should always be in visual and real time indicators of what's ahead, and what's below. What i was wondering is how far ahead can a depth sounder reach? 20 meters, 100? I know that coming into Harbour Island can be beyond dicey, and that's in the day....the right below water line submerged reefs are like a parking lot in some areas. I would deem it impossible to nav in low light or night.
    I guess you could always tie a weight on a string....oh, that's been done.
  11. tirekicker11, Nov 16, 2011
    #11
    tirekicker11

    tirekicker11 Senior Member

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    EchoPilot - 3d Forward Looking Sonar
  12. Pascal, Nov 16, 2011
    #12
    Pascal

    Pascal Senior Member

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    If you think you can rely on charts to make it thru tricky spots, you are in for a rude awakening! Sure in places with rocks, it may work since rocks don't grow overnight but anywhere with sand/mud shoaling like the Bahamas, or most of the US easy coast chart soundings can t be relied on

    Problem with most forward looking soundera like interphase or echo pilot is that they are limited to 5 to 8 times the depth. In 10' of water you won't see much beyond 60 to 80' forward of the transducer, or just beyond the bow.
  13. Capt J, Nov 16, 2011
    #13
    Capt J

    Capt J Senior Member

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    And in my experience they only work properly if you're doing 5 knots or less and in relatively calm water.
  14. Pascal, Nov 16, 2011
    #14
    Pascal

    Pascal Senior Member

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    Well if you re worrying about depths, and are down to just 3 or 4' under the wheels in unknown waters, chances are you won't be making more than 5kts!
  15. NYCAP123, Nov 17, 2011
    #15
    NYCAP123

    NYCAP123 Senior Member

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    Doesn't sound like a place I'd cruise at night unless it's well marked or I knew it very well.
  16. Capt J, Nov 17, 2011
    #16
    Capt J

    Capt J Senior Member

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    LOLOLOL, what markers? they don't have any. And very few people can say that they know it very well. I've gone out of there without a guide but you really have to be on top of things, and pay lots of attention, there is no margin for error.
  17. NYCAP123, Nov 17, 2011
    #17
    NYCAP123

    NYCAP123 Senior Member

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    Right. Isn't this the place where that 50 SR lost it a few years ago that was all over YF? And someone would attempt to come in there at night why?
  18. Pascal, Nov 17, 2011
    #18
    Pascal

    Pascal Senior Member

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    Yes, and it s not called the devil s backbone for nothing...

    There is a company who s started gathering real time depth data using GPS and sounder linked to a black box, forgot the name. Interesting concept... They supply the black boxes and it uploads to their servers by wifi
  19. Capt J, Nov 17, 2011
    #19
    Capt J

    Capt J Senior Member

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    Because they weren't intelligent enough to read a cruising guide first before going there and attempting it. Just because someone can own a yacht, does not mean they have the brains to properly navigate with it. hehehehe