>Is there an easy way to remeber how to allow for magnetic deviation?

This is going back into my boating training... might be a little foggy, bear with me...

Often, when people talk about "deviation", they're actually talking about "variation". I think that's probably what you're asking about. On most maps and charts, there will be a compass rose of some sort that will show magnetic and true north. The difference between them is the local [color:"blue"]variation[/color] at that point on the chart.

For example, here in Massachusetts, on the coast, I have a nautical chart that shows a variation of 15 degrees 45 minutes West. When my boat compass is reading North (magnetic), my boat is actually facing west of True North. I'm on a heading of 344 degrees 15 minutes true, even though the compass says 0. I subtracted the variation from the magnetic heading to figure out my true heading.

[color:"red"]A general rule of thumb for variation is this:
Think of variation as an error in your compass relative to finding True North. You want to correct that. If the variation is East, you add it to arrive at true north, Think CAE, Correct Add East. If it's west, like my example above, you subtract. [/color]

Deviation, is normally used to refer to the influence that electronics, wiring, and other magnetic objects have on what your compass will read. On a ship, where most of the things that might affect the compass are in a fixed location, there are methods for determining deviation. For the most part, in the wilderness, deviation is assumed to be zero if you take your compass readings away from metallic objects and electrical influences.

For instructions in a survival kit, you might not want to even worry about deviation, other than saying you should take readings away from metalic objects. For variation if they have a chart, it probably has magnetic north on it, so they can use that when plotting their courses. Half the time, in survival situations, I'd think that the compass will be used to just keep them going in the same general direction, rather than a specific one. They may not even have a map.

Sorry for the long winded answer, I'm sure there are some details I left out that someone else can fill in. I don't know the rule of thumb elsewhere, but, in the US, there is something called the "Agonic Line", where variation is zero. It runs from the North geographic pole, through the North Magnetic pole, and down through the US through a point west of Tampa, FL. Anywhere east of that line has a West variation, and if you're west of that line, you'll have an East variation. Fun eh?

There are a couple places that do a nice job of getting into the details of this. I have done a lot of hiking and orienteering , but, I learned compass and mapping skills originally through boating. Specifically, the US Power Squadron and Coast Guard Auxiliary have some great courses that help with navigation skills on and off the water. A great reference, in a book, is "Chapman's Piloting". It's the bible for boaters. For hiking, I think that several of the outdoor schools do good work with map and compass skills, but, you basically need to get out there and do it when you don't need to, so you're comfortable with it when you do.

I hope you'll share your survival kit info sheet with us when you're done. <img src="/images/graemlins/smile.gif" alt="" />