>> Steve Scherrer wrote: > I would skip the part about looking for a compass with adjustable > declination/ variation. We teach boaters to NEVER use this feature as it > will be a different bearing than the Marine compass on your deck, with no > adjustment options. Don't get confused, don't adjust variation on the > compass. I would absolutely agree with this statement with one exception. I have spent many years in the backcountry with USGS maps and also do a fair amount of land surveying in my business and career, I also own a number of different compasses and other devices for overland navigation. It is almost impossible to prevent inadvertent errors when using magnetic compasses without an declination adjustment on the compass when doing overland navigation. So if you intend to use your hand held compass for backpacking or route find inland then you must have a declination adjustment. I would almost say it is mandatory if you do any serious backcountry overland travel. When I learned about nautical navigation I was surprised to learn that there is no need to ever concern yourself with declination because the charts are all set up be able to use magnetic north exclusively (perhaps the USGS who makes the land maps could learn something from the nautical charts). If you never intend to use the hand held compass for land navigation then absolutely you do not need or want to worry about declination, it would only serve to confuse you. Especially in far North locations where the declination is very large. In my business every time I have to explain magnetic North to trainees I always get a lot of confused looks. It is actually not that easy for most people to visualize whether you add or subtract the declination when going back and forth from the map to the compass. FYI you do not use a magnetic compass for land surveying but often on remote properties we have to dead reckon to locate monuments or reface markers, or even find the property we are supposed to survey. Without the ability to locate a surveyed reference point the rest of your work is of questionable value. Unfortunately the inexpensive GPS units do not have nearly the accuracy you need to find a small metal marker in heavily overgrown forests, so very accurate navigation become essential to locate them. Peter *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************Received on Tue Feb 13 2001 - 16:35:15 PST
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