Using a Compass to Determine When to Tack

[zz4gta]

You got it. Paper does work, but it's a natural enemy of water. A wipe board or "write in the rain" pad works really well for wet boats.

Or, you can spend $400 on a tactic electronic compass that tells you when you're lifted or headed.

[COOL]

The compass has many tactical uses,
before and during a race.
Beginning with, when arriving at the starting area
I make periodic checks of the true wind direction
by luffing head to wind until the boat is nearly stopped
and noting the compass heading. I will also sail upwind
on both tacks and note the headings always trying to
determine if the TWD is shifting.
I use the compass to determine the 'favored' end
of the start line by doing a 'wind check' near the line
and comparing the TWD to the bearing of the line
from one end to the other.
Once you are on a beat watch the compass
for lifts and headers. If the wind is oscillating you
may want to tack on the headers. But many venues have
a persistent shift, in which case it some times pays to
sail on the headed tack a little longer to gain more
leverage as it continues to shift.