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6. INSTALLATION
As was pointed out in the Introduction to this manual, this machine can do its intended
functions only if it is installed properly.
GENERAL MOUNTING CONSIDERATIONS
This radar consists of two units; the Display Unit and the Scanner Unit. The scanner unit
has been designed to withstand all the rigors of the marine environment, and if installed
properly, is thoroughly waterproof. A "domed" type of scanner unit, where the scanner
mechanism is enclosed in a thermoplastic resin dorne, ensures that halyards and other
rigging won't get tangled up in the rotating scanner.
The display unit is carefully constructed to be able to withstand the humidity and
corrosive atmosphere common in a pilothouse, but it is not designed to be used outside,
directly exposed to the environment!
Many owners will undoubtedly use this radar on small boats. The display unit must be
mounted inside an enclosed cabinet.
Corrosion can occur, espedally on the rear
connectors exposed to salt spray, unless these are taped and thoroughly sealed with putty
compounds made especially for this purpose. Most small boats are equipped with such an
enclosed cabinet, and most have clear doors so that equipment may be seen behind them.
It is rarely possible to place the scanner unit where a completely clear view in all
directions can be obtained. Thus, the angular width and relative bearing of any shadow
sectors should be determined for their influence on the radar at the first opportunity after
fitting.
(The> method of determining shadow and blind sectors is shown later in this
section.)
The scanner unit should be generally mounted as high as possible on the boat to ensure
best performance at the maximum range. But this is per haps not as im por tant as mlght
be supposed for a small boat. For example, increasing the height from IQ feet to 13 feet
off the water won't net very much if you are looking for another boat whlch also only rises
10 feet off the water. Doing so would increase the range capability from 7.7 nautical miles
to 8.3 nautical miles, an increase that may not be worth the serviceability problems
involved in mounting the scanner higher on the boat.
In addition, if your boat is equipped with a radio direction finder, its antenna should not
be positioned in close proximity to the scanner unit, since the DF would be adversely
affected. A separation of more than 2 meters is recommended.
The compass safe distance (3.1m (10.17 feet) standard compass and 1.75m (5.74 feet)
steering compass) should be also observed. If the distance is not enough, deviation of the
magnetic compass will result.
On a sailboat, the scanner unit is normally mounted up on the mast. An antenna bracket
may be optionally supplied to mount it with ease. See page 6-5. On power boats, it is
usually installed on a framework above the flying bridge. However, in many cases, the
unit can be installed directly on the top of the wheelhouse near the ship's centerline.
The display unit consumes only a moderate amount of power, so there is no need for
forced air ventilation. However it is necessary to provide adequate space behind and
around the display unit to allow some circulation of cooling air and to provide convenient
access to the rear connectors.
Even though the picture is quite legible even in bright sunlight, it is a go od idea to keep
the display unit out of direct sunlight or at least shaded because of heat that can build up
inside the cabinet.
It is a regrettable faet of modern life that small attractive electronic gear seems to attract
undue attention from thieves. In your installation planning it is a good idea to provide
means either to hide the gear when you are not aboard or take the gear off the boat
completely when you are finished for the day. Consideration should be made to provide
space for access to the mounting hardware on the side and to the connectors behind the
display unit.
SCANNER UNIT INSTALLATION
The scanner unit is completely watertight when installed correetly. It should be placed
where there is a good all-round view with, as far as possible, no part of the ship's
superstructLire or rigging intercepting the scanning beam. Any obstructions will cause
shadow and blind sectors. A mast, for instance, with a diameter considerably less than
the width of the scanner, will cause only a small blind sector, but a horizontal spreader or
crosstrees in the same horizontal plane as the scanner unit would be a much more serious
obstruction and the scanner unit would need to be placed well below or above it.
When this radar is to be installed on larger vessels, take care to consider the following
points.
1) The interconnection cable is run between the scanner unit and the display unit. If
additional interconnection cable is required for a particular installation, an unbroken
length of cable must be used (i.e., no splices allowedl), and maximum length of the
interconnection cable is 30 meters. On a sailboat where it will be necessary to step the
mast for maintenance, a junetion box may be installed at the base of the mast, under
the floorboards. The junetion box must be watertight and the wire breakout must be
kept as short as possible.
2) Deposits and fumes from a funnel or other exhaust vents can adversely affeet the
performance of the antenna, since hot gases may warp the radome. The scanner unit
must not be mounted in a position where it may be subjected to temperatures in excess
' of70"C(I58°F.)
The figure below shows typical scanner unit placement.
Fig.6-1 Typical Scanner Unit Placement
6-1
6-2
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