A hand-bearing compass is most useful on a boat enabling you to easily take a magnetic bearing of a fixed point such as a lighthouse or headland, or even a star. After adjusting the bearing for magnetic variation (the difference between magnetic north and true north) and deviation (the magnetic influence of other items on the boat) a line can be drawn on the chart along the corrected bearing to the object, and you’re on there somewhere. Take bearings on two objects consecutively and where the lines cross …. is somewhere near where you are. Take bearings on three objects? Now you’re talking. A very useful item if you are near the coast.
Aboard The Aegre we first had an inexpensive one that you held at arm’s length and sighted over while pointing it at the lighthouse or whatever, and read the bearing from the magnetic card floating in alcohol to dampen its movement a bit. It was light to hold but not very precise.
But that’s not the one I’m writing about here.
It might have been in Barbados or Panama that a nearby yacht in the harbour had a garage sale, and amongst treasures going cheap we spotted a little Suunto hand-bearing compass.
It was near flat and smaller than the palm of my hand and seemed carved out of a block of stainless steel. With its short red lanyard tight around my wrist I braced it against my cheek and could sight through it, to see the floating card scale clearly projected ahead. By keeping my other eye open the scale was as if projected onto the horizon. Thus it was easy to take quite accurate bearings, the card being nicely damped in alcohol.
It was a lovely instrument to use. I treasured it and still have it.
I hadn’t anticipated using it to measure the bearings of stars, but it was perfect for that too, as I explain in the book.