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    Re: Teaching seamanship
    From: Derrick Young
    Date: 2004 Oct 14, 17:27 -0400
    I am a not a CN fanatic - but I thoroughly understand the issues with the over reliance on an appliance or gadget.  I also understand something (I hope) of what happens when things go bad.  I very clearly remember a rocket launch from Wallops Island where the engineer swore that there was propellant in the guidance control system because hydrogen peroxide coming out the overflow.  I watched the telemetry and saw that the high pressure control had failed.  So when he tried to load the peroxide, the bottle had collapsed and the fluid immediately went out the overflow.  In spite of what I showed everyone on the telemetry, they launched.  We dropped a 2.5mil (US$) payload in the south Atlantic.
    On the boat, I have two GPS units mounted, helm and galley, independent antennas (different sides of the boat and short, enclosed cable runs) and different power sources.  I have two LORAN-C units, also helm and galley with the power supplies switched from the GPS units.  I have one RDF unit (helm only), mainly because of the antenna.
    In the ditch bag is a GPS, LORAN-C, VHF-FM radio (all handheld) with multiple sealed containers holding extra batteries and a PEPIRB, three days emergency rations for each person on board, emergency blankets, another sextant (plastic, but it is there) with plasticed lifeboat tables and attached wax pencil, signal mirrors, dye packs (4), mini handheld and aerial flares (3 each), horn, whistle, salt water power lights, multiple fishing kits, medicine kits and plastic covered mini-charts for the area that we are in.  Made an assumption here - that either my wife or I will have a working watch.  With each adult PFD, there is a belt pack containing mini-flares (3), dye packs (2), signal mirror, salt water powered light, knife (with attached lanyard).  My son's PFD does not have the knife.  Two PFDs (mine and my wife's) also have PEPIRBS attached.
    Going to your scenario, in an ocean crossing (big pond or little pond), it is not necessary to take a LOP or even a fix every 12 hours or 24 hours.  If you have one LOP every couple of days, great.  If not, then you fall back to that oldest of navigation skills, a DR plot.  When the sky finally clears, or you have a short break in the weather, take your sight, develop your LOP, take your course/speed data from your log and advance the last LOP to your current one (1 day, 2 days, 3 days whatever needed) and you have a "running fix".  Is it accurate? Probably not - but it is a start.  As you already know, the longer the time between LOPs (regardless of how they are developed, e-nav or other) the lower the confidence in the running fix - goes back to the quality of the fix discussion.  But the same discussion applies to the GPS reported positions when there are not enough satellites available. 
    If I was concerned about running aground after several days in the ocean, then I have a couple of decisions to make - beef up the deck watch and have them watch for signs of land (watching for land based birds mostly) and/or if the chart shows a gradual reducing depth of water, then pay out the anchor some reasonable amount (150 ft?) so that we come to a stop before going aground - if the anchor won't work because the water change is too drastic, then you are back to changing the deck watch.
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