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    Re: Magnetic variation changing faster than anticipated
    From: Mark Coady
    Date: 2019 Feb 26, 21:06 -0800

    The magnetic compass is still a treasured tool for the small vessel navigator, at least archaic ones like myself who also still carries paper charts as informative tools. 

    By a magnetic compass I automatically assume it is properly compensated for deviation and if it is over a degree (you can't steer a whole lot better anyway), then a deviation table is available.

    Why do some of us small boat navigators cling to that fritzy wobbly thing that can be upset by a magnetic screwdriver left on the dash:

    1. It provides reliable vessel heading data in a simple package.  Remember heading and track are not the same. Just cause I'm pointed a certain way does not mean I am going there. I've fished in places where trolling at 4 knots forward is a slipping sideways track at 45 degrees without a compensating heading adjustment. Yes I know a modern marine GPS can calculate required heading on long enough course legs, and gives you a visual that you are going a astray, but a compass is so damned easy.

    2. We still construct courses and voyage segments based on bearings and distances. Estimating heading vs track is important, and doing it frequently allows you to learn a lot about current and wind set effects on your vessel. Nice to know for dead reckoning purposes.

    4. Being able to give a bearing from a known position to an observed object such as a flare can be very helpful. Example: If I relay my precise position and an accurate bearing, I have a basis for a search or estimating an unknown distress position using distance clues. I note that most of us were clearly instructed to give information in "True" coordinates, so variation doesn't intrude into current or future history. I realize for short sea distances it might not matter so much, but it pays to know what and why at all times and to be consistant. 

    4. We still learn storm avoidance and intercept courses based on plotting bearings, etc.  I think maintaining proficiency with a compass helps comprehension. I can't recall off the top of my head how to do an intercept with a moving target hours away on my dash GPS, but I can get a required track and estimated heading quickly with a compass rose and simple vectors on a chart. Intercepts are a handy skill to meet another vessel for spare parts or other emergencies, even if both are moving.

    5. I have used a handheld pelorus for amazingly accurate ranges locating sunken objects such as wrecks.  I am sometimes given ranges from another vessel that had no GPS fix.  I hit a wreck some years ago within a few yards replicating accurate bearing compass sights. I used a pair of my father's old German binouculars with a compass. (I still carry them).

    4. A well compensated magnetic compass allows you to take advantage of accurate bearings for certain celestial observations if you are so inclined.  Sunrise, compass checks, what star is that, bearing and elevation?, etc...

    So its all in the eyes of the beholder...yes there is probobly not much I said can't be done on the GPS screen nowadays if you are so inclined....and yes..I could carry four more GPS units for the price of a good compensated compass.... but I for one will keep it.  

    I will say on many modern craft its appears to be a decoration...when I purchased the 35 footer last year...the big PA speaker with a nice permanant magnet was mounted on the downslope of the bridge under the running light. 3' feet away and forward of the steering compass.  Funny thing about this boat... LOLOL ......it always points North....considering it was built 35 years ago, I wondered how long the speaker had been there and if anyone ever wondered why the compass seemed a bit off.

    My personal fault......I just can't quite let go of the quaint notion that that 99.999 or whatever it is GPS doesn't need an alternate.  No batteries, just skill and common sense.  Part of it is just plain we embrace the familiar, because it always worked...and if it works..don't mess with it... 

    I always have a waterproof chart on the dash of my present location. LOL  I have never had the batteries go dead on one yet....and I can write notes to self on them whenever I want.

       
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