Home Made Compass Card

The compass rose cut out from a chart makes a compass card. Tape it to a board, extend its radii and place it under your compass bowl.

If you do not have a spare compass rose, or a protractor to draw one, fold a square of paper (see Figure 6.5 and Figure 6.5b), to get eight compass points. Insert

If you have no protractor you can make a compass card by folding a square of paper to find these eight principal points. All the other points have to be inserted by eye. Fortunately the human eye is quite good at halving angles.

Human Eye Xyz

SOUTH

EAST1

SOUTH

EAST1

Once you have marked out the card stick it to a sheet of eavy card or ece of plastic or wood. Failing that, place it in a clear plastic bag, tape it hut and then ape the card where it can be easily read.

6.5b A Homemade Compass Card

the rest by eye or by geometrically bisecting the angles as in Figure 6.5c. When you have all 32 points, label them, see Figure 6.6.

If you wish to work in degrees then draw a circle with a radius of 57 units. The units can be any you wish: millimetres, tenths of an inch, or the thickness of a couple of coins taped together, see Figure 6.7. The circumference of a circle with a radius of 57 units is almost exactly 360 of the same units and one unit around the circumference represents 1°.

6.6 Traditional 32 Point Compass Card

6.7 Using Coins for Small Measurements

A home made floating compass is useless for taking bearings. For doubling the angle on the bow (see Chapter 12) you may wish to make a pelorous where the bow is 0° and the card is marked 0°-180° port and starboard. When you align the 0° -180° line along the centreline of the boat, all angles measured with this pelorous are relative (see Figure 6.8).

Celestial Bodies Human Body
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