Bart Bear's Blog

Scruffy and I are examining the binnacle compass on the "James Craig". In the days before GPS and radio compasses, these compasses were the main way of navigating a ship. Because the ship bounces and rolls in the waves, the compass is mounted inside a pair of hinged rings that let it stay level all the time. The compass body is made of brass. If it was made of iron it would muck up the magnetic compass needle. In fact all of the metal in the ship has an effect on the compass needle, so it has to be carefully measured and balanced out. The two metal balls on the sides of the compass stand are part of the magnetic balance system, making sure that the needle always points north. Scruff and I figured out how this one worked and had a bit of fun balancing on the moving rings as the ship rolled, but eventually the helmsman (who was a lady) made us get down so that she could see the compass without a small bear being in the way.

Labels: boats, New South Wales, Sydney