ComNav P4 - SPU Mounting and Wiring

ComNav P4 Installation and Operation
Document PN 29010100 V1r0 - 44 -
Control Head
The P4 Control Head is typically mounted in the vessel’s wheelhouse. It can also be mounted in
more exposed locations, such as on a flying bridge, since it is fully splash-proof (however be advised
that the P4 Control Head is not submersible).
When ordered as part of a P-Series System, each Control Head is supplied with a flush mounting
kit, including a bracket for flush mounting. The flush-mount is meant to be used when the Control
Head is installed inside the boat. If using the optional Deck Mount or commonly known “Trunnion
Mount” bracket kit; the unit is generally mounted on the console or in an overhead bulkhead
location.
Complete instructions, including drilling and cutting templates for each type of mounting, are included
with each kit.
Electrical Connection
Route the Control Head cable to where the SPU will be located. Avoid running the cable parallel to
antenna cables, AC power, or DC wires/cables carrying heavy current to minimize interference.
Excess cable can be coiled up, or the cable can be trimmed to a suitable length.
See the Control Head section for details on connecting the cable to the SPU.
Signal Processor Unit
The SPU should be mounted in a clean and dry location inside the vessel, and away from heat,
moisture, and liquids of any kind. It should be somewhere central: ideally between the Control Head,
the main electrical panel, and the rudder drive system. It need not be visible during normal operation,
but it should be located so that there is easy access to it during wiring and maintenance operations.
Typical locations are next to the electrical panel, at (under or above) the Navigation station, or in a
dry storage locker in or around the wheelhouse.
The SPU should also be mounted far enough away from your boat’s magnetic compass or
compasses, so as to minimize any electrical/magnetic interference. A good rule-of-thumb is at least 1
metre (3’) away, but see the Compass Safe Distances section for specific values, if you do not have
that much space.
The SPU can be mounted vertically on a bulkhead, or horizontally on a deck or shelf.
 If mounted vertically, the SPU should be positioned so that all wires and cables will
exit from the top of the unit running left and/or right as appropriate, from the SPU
connectors, secured with terminal strip or tie wraps( customer supplied).
 If mounted horizontally, all wires and cables should have a drip loop formed in them.
Each SPU is shipped with a package of four (4) mounting feet and an instruction sheet that includes
dimensions for drilling holes to fasten the feet to the boat.
See the Wiring the System section for SPU wiring details.
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