Catalina Capri 22 Owner's Manual page 58

(
as a lightning conductor system. Where copper is used, it
should be of the grade ordinarily required for commercial
electrical work, generally designated as being of 95
percent conductivity when annealed.
Ap.6 External Ground Plate - An exterior grounding
plate of copper, copper alloys, stainless steel or aluminum
may be provided by means of a plate which has an area of
at least one square foot (0.1 m
2
)
area. The plate should be
located as nearly as possible directly below the lightning
protection mast. The boat's propeller(s), shaft(s), metallic
rudder(s), and other metallic surfaces that have the
required area, can be effectively used on small boats only
where the lightning protective mast is located at the stem,
above the in-water metallic objects to be used as the
lightning system ground. The stem mast must be tall
enough to provide a cone of protection that extends to the
bow of the boat.
Ap.6.1 Boats that use a lightning grounding plate
instead of the lightning grounding strip should ground
backstays, or other objects aft, to the engine negative
terminal, a metallic rudder, or other external ground at the
aft end of the boat. The lightning ground shall not be
routed through the boat to the lightning grounding plate
forward under the lightning mast.
Ap. 7 Grounding Strip - An external grounding strip of
copper, copper alloys, stainless steel, or aluminum,
installed under the boat in a fore and aft direction, may be
used as the earth ground connection for the lightning
system. Except for stainless steel, the strip should have a
minimum thickness of 3/16 inch (4.8mm), and a minimum
width of 3/4 inch (20mm). Stainless steel should have a
minimum thickness of 1/8 inch (3.2mm). The length of the
strip should extend from a point directly below the
lightning protection mast, to the aft end of the boat, where
a direct connection can be made to the boat's engine, but
the total length of the strip shall not be less than four feet
(1.22m). In a sailing vessel, the backstay and engine
should be connected to the aft end of the strip. The strip
should be secured to the hull with one, or preferably two,
galvanically compatible through bolts at each end. The
use of two bolts at each end, spaced one or two inches
apart, will help prevent any tendency for the strip to rotate
when the electrical connections are made inside the hull
The strip must be located so that the external strip is
submerged under all operating conditions. If the strip is
not located so as to be submerged when a sailboat is
heeled to port or starboard, then a strip will be required on
both the port and starboard sides. All connections to the
strip should be as short and direct as possible. Additional
thru-hull bolts may be located along the length of the strip
for additional connections, such as on a two masted
sailboat. Because of the possibility of stray current
E-4
12/96
corrosion of the securing bolts, the number of thru-hull
bolts should be kept to a minimum. To minimize the
number of thru-hull bolt connections, an equalization bus
can be installed.
Ap. 7.1 The aft end of the lightning grounding strip
should be connected directly to the engine negative
terminal. This will provide a path inside the hull for any
DC stray currents that might be imposed on the thru-hull
bolts that attach the lightning grounding strip where those
bolts contact bilge water.
Ap.8 Protection of Equipment - Wherever possible,
electronic equipment should be enclosed in metal cabinets
that are connected to the lightning grounding system with
a minimum #8 AWG (8.39mm
2
)
conductor. Surge
suppression devices should be installed on all wiring
entering or leaving electronic equipment.
Ap.8.1 The grounding of metal rod type radio antennas
provides some protection for boats without masts and
spars provided that
Ap.8.1.1 conductors in the grounding circuit of the
antenna have a conductivity equivalent to #4 A WG
(21.2mm
2
)
copper in accordance with E-4.5, and
Ap.8.1.2 the top of the antenna is not more than 50 feet
(15m) above the water, and
Ap.8.1.3 a line drawn from the top of the antenna
downward toward the water at an angle of 45 degrees to
the vertical does not intercept any part of the boat (see
E-4.8), and
Ap.8.1.4 the antenna loading coil is provided with a
suitable protective device for bypassing the lightning
current.
NOTES: 1. Because a loading coil presents a ltigh
impedance to the flow of lightning current, the portion
of an antenna above tlte bottom of a loading coil
is not
as effective as a liglttning protective mast
2. Non-conducting antenna masts with spiral
wrapped conductors are twt considered suitable for
lightni11g protection purposes.
Ap.8.2 In order to protect the radio transmitter, antenna
feed lines shall be
Ap.8.2.1 equipped with a means for grounding during
electrical storms, or
Ap.8.2.2 protected by lightning arresters or lightning
protective gaps.
© 1996 American Boat
&
Yacht Council, Inc.
7