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    Re: Varuna -- Abandoned due to Loss of Power
    From: Lu Abel
    Date: 2017 Sep 10, 17:04 +0000
    Dave C wrote:

    <<  chart plotters that allow the boat occupant to specify a route from A to B and the system will (or claims to) drive the boat safely around rocks and reefs  >>

    Be careful when using this type of feature.  Situational Awareness is still very important.  I received a letter from the IHO, a couple of years ago, warning that this type of function can fail due to the inconsistency of how objects such as rocks, reefs and obstructions are encoded in ENC charts from various HO agencies around the world.  Everyone that officially supports ENC charts in their product (ENC Stakeholders) would have received the same letter. 


    Even more important is the fact that chartplotters, at least as sold to the recreational boat market, not the industrial-grade plotters that are allowed on commercial ships in lieu of paper charts, and therefore do not directly use government-issued electronic ("ENC") charts. 

    Instead they use "chart cartridges" issued by third parties. And these chart cartridges are not produced by the folks that produce the actual chartplotters (displays). 

    While I would welcome a chartplotter on my boat (I do not currently have one), I have also seen examples where their displays were inadequate or even incorrect.

    My first encounter with chartplotter inadequacy was two decades ago.  I attended a boat show.   Several chartplotter vendors were displaying their latest wares.  In one vendor's booth (don't remember which brand name, and it is irrelevant) a plotter was turned around so visitors could play with it.  The display was centered on the location of the show.  I easily figured out how to scroll the display and moved it to a very popular anchorage in a nearby island.   Both of the most common and logical approaches to the anchorage have reefs jutting out from the shore.   Both reefs are well marked with buoys.  But the chartplotter display showed neither reef and neither buoy!!!

    I immediately looked for the most senior person I could find in the booth and pointed out to him that someone could buy his product at the show today, install it in his boat tomorrow -- and rip the bottom of his boat out trying to visit this popular anchorage.  He simply shrugged and said "we don't make the cartridges"

    Subsequently at every show where an actual cartridge provider had a booth, I asked how they ensured that the data on their electronic charts was complete and correct.   In every case I was told "that's proprietary information." 

    Fast forward to just this year.  I live in the San Francisco Bay area.  For those who might not be aware, the Bay is very shallow and gains depth very slowly as one goes offshore from the eastern shore of the Bay, home to cities such as Oakland and Berkeley.  A friend invited me out on his brand-new 34' cabin cruiser which he has equipped with thousands of dollars worth of the latest and greatest electronics.   We exited a secondary bay along the eastern shore with the intention of cruising northward to another secondary bay.  His boat has about a 3 ft draft and the tide was 3 ft above MLLW and was rising.  We could have easily cruised across 3 ft soundings with lots of water under our keel.  But his latest-and-greatest chartplotter displayed very few soundings inside the one-fathom contour - far fewer than a paper chart of the area!!!!

    My bottom line:   Do not confuse recreational boat chartplotters and their charts with government issued ENC charts.

    There is hope, though -- there are now inexpensive apps available for iPads and their non-Apple equivalents that can display actual ENC charts.   And their memories are great enough to hold many, many charts.

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