58 seamanship secrets
Card readability. Stand in front
and to the side of the compass. Move
the compass to diff erent heights to
simulate sitting or standing at the
helm. Position the compass to match
your likely viewing angle in practice.
Step back and look at the display. Is it clear and easy to read without eye-
strain? If you like what you see, go to step #2.
Off set lubber lines for sailors. Lubber lines are lines drawn onto or
fi xed to the compass glass. Th e person steering the boat lines up the course
to the fi xed lubber line. For instance, if you wanted to steer 045 degrees
magnetic, you would turn the boat until 045 lined up with the lubber line.
Some sailors prefer to use two additional lubber lines, off set by 45 degrees
to the main lubber line. Th ey use these for tacking and jibing maneuvers.- Test before you purchase
Oscillation test. Remove the compass from the box and rotate it in
a horizontal plane through 360 degrees. The card should be completely
free of friction (sticking) and not bind against any part of the housing.
Repeat the test in the opposite direction.
Recovery test. Place the compass back on the shelf and align the
lubber line with one of the numbered 30-degree markings. Hold your
magnet to one side of the compass housing. The card will begin to spin
toward your magnet. Wait until the card stops all movement, and then
quickly remove your magnet to a distance of at least 3 feet.
Smaller cards should move back to the original mark immediately.
Larger cards might make a small swing past the lubber line, but should
move back to the original mark without further oscillation. The card
should stop within 1 degree of the original reading. If not, the compass
pivot, card, or fluid viscosity could be defective.
“ZERO” A STEERING COMPASS BEFORE YOU INSTALL
You’ll want to make sure your steering compass is free of internal errors
before mounting it on your boat. Most magnetic compasses have internal
compensating magnets, which are used for aligning the compass card. These
magnets sometimes move during shipping, causing a permanent internal
error. Remove all internal error by “zeroing” the compass.
The procedure is fussy but simple. Here it is:
- Find a test area. Find a location without any nearby metals, electrical wiring,
or other magnetic infl uences. Th e fl oor or a wooden table might make a
good base for zeroing. Sometimes it’s easier to locate a good place outdoors.
Tool Needed for Testing
a Compass
X small magnet