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Navigation & Publications
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Accuracy, dependability and craftsmanship make
Globemaster the popular choice on the world's
finest sail and power boats. The 5"dia. PowerDamp
flat card uses a precise, lightweight gimbal system.
A fiberglass-reinforced spherical bowl with a high-
capacity roller diaphragm ensures accuracy, even
in extreme temperatures. Highest-quality sapphire
jewels and pivots and DirectiveForce magnets
make it highly accurate and fully compensatable.
Brushed stainless steel binnacle mount fits all
wheel steering pedestals. Includes 12V DC Green
NiteVu night lighting.
Globemaster SP-5C Binnacle-Mount Compass
Apparent Card Dia.:
Brushed stainless steel
7 1/4"H x 7 1/8"dia.
90, 45, 0
Do you want
How will you read
the compass card?
How big should the
apparent card diameter be?
What mounting style
do you need?
Selecting a Steering Compass
Compasses allow you to steer your boat on a
magnetic heading and to take a magnetic bearing.
One advantage of electronic compasses is that their
sensors may be mounted remotely in many cases.
This allows you to place the sensor where it will be
least affected by moving magnetic fields and the
motion of the boat. Of course, it does increase the
complexity of the installation.
What mounting style do you need?
Size and mounting style are the most important crite-
ria when selecting a compass. There are five basic
compasses are set in a cutout in a
horizontal surface with half above the surface and
compasses are highly versatile
since the bracket can be mounted on surfaces with
different tilt angles. They can also be removed easily
for storage or security.
compasses are popular in smaller
cruising sailboats (without a binnacle) and on the
dashboards of small powerboats, where they are
sized and styled to match the other instruments. The
aft bulkhead of a sailboat's cabin provides good vis-
ibility in the cockpit, but is sometimes inclined away
from vertical. Some compasses can mount at angles
of up to 45, but others require a leveling block to
make their internal gimbals work properly
compasses sit on top of a surface
and can be easily removed by pressing two buttons.
Mounting is easy, as no large holes need to be cut.
compasses also mount on a sur-
face or steering pedestal, like those used on wheel-
steered sailboats. Powerboat owners select them
when there is no room under the mounting surface
for a flush-mount compass to protrude.
How big should the apparent card
We refer to a compass card's "apparent" size
because the dome and fluid inside it magnify the
actual card size. Bigger compasses have better
performance for several reasons. They are easier to
see from a distance or under poor lighting and have
larger numerals, markers and lubberlines. With the
larger volume of the compass bowl and more min-
eral oil fluid, they have more effective damping of the
motion of the compass card.
How will you read the compass card?
There are two basic types of traditional compasses:
direct reading and flat cards.
Direct reading cards:
The heading is read from the
side of the card nearest the helmsperson. This is
more logical for some users, as you don't have to
peer into the compass to see the heading. Direct
reading cards do not bisect the compass dome,
however, and therefore have more movement in
The heading is read by looking inside
the compass dome, on the forward side of the card.
These compasses generally have lubberlines (head-
ing references located in the direction the boat is
traveling) and additional lines at 45 and 90 to the
Dual reading cards:
Read like both direct and
flat cards. These are almost exclusively bulkhead-
mounted sailboat compasses, and can be read
more easily from the sides than conventional cards.
Digital numeric displays
are how electronic com-
passes display a heading. They often use cardinal
and intercardinal (i.e., N, NW, W, SW, S, SE, E, NE)
descriptions as well. Some boaters prefer to see
their heading displayed spatially on a compass card
in the traditional manner, relative to other points on
Do you want a clinometer?
This question applies mainly to sailboat owners. A
shows your angle of heel, useful in de-
ciding when to reef or shorten sail.
sailing compasses, usually at 45 angles to your
heading, help you steer your sailboat when you're
sitting on the windward or leeward rail.
Southern Hemisphere "dip":
All compasses we
sell, whether they're steering compasses, hand
bearing compasses or those in our binoculars, are
intended for Northern Hemisphere use only. We can
provide compasses that are "balanced" to compen-
sate for the downward magnetic force that would
otherwise cause the card to "tilt" at locations south
of the equator. These are often available through
Do you want a magnetic
or electronic compass?
Do you want a magnetic or
Magnetic compasses contain a free-spinning
, which aligns with the Earth's magnetic
field and points in the direction of magnetic north.
Small onboard magnetic fields, caused by ferrous
metal (a steel steering wheel or iron engine block),
magnets (a speaker or microphone), or current-
carrying wires can divert the compass away from
magnetic north. This
must be corrected
by moving the compass away from the local mag-
netic interference (if possible) or by adjusting small
compensating magnets inside the compass (using
a process called swinging the compass). For de-
viations too large for the compensating magnets,
usually greater than 20, a deviation table may
need to be created.
Electronic fluxgate compasses
measure the rela-
tive strength of magnetic fields passing through
two coils of wire. Using sophisticated electron-
ics, these sensors can deduce the direction of
the Earth's magnetic field. They are still affected
by local magnetic fields like steel components
and speaker magnets, but they can compensate
electronically for those fields that do not change in
strength or location.
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