Simrad RC37 User manual

20221370A 1 07.06.04
RC37 RATE COMPASS
INTRODUCTION
Simrad RC37 Rate Compass is a fluxgate compass with a built in rate sensor that
significantly improves the dynamic performance of the compass. This makes it an
excellent heading source for autopilots, chart plotters, radars and other equipment that
will benefit from the dynamic characteristics of RC37.
Heading output is on sine/cosine and NMEA0183 formats.
The technical specifications are printed on page 4.
The RC37 Rate Compass (part no. 22084446) can be used as a high performance
heading sensor on the following Simrad or Robertson autopilots: AP45 and AP9MKII –
Mk3. It replaces the previous RFC35RS and is a high performance alternative to
RFC35N and RFC35NS.
RC37 comes with a 15 m (49’) open end cable wired for NMEA0183 input and output.
The internal connections of the wires are shown on Figure 2.
Notes !
1. Figure 2 shows the connections when the compass is used as a stand alone
NMEA compass. An extra cable gland is supplied for a separate supply
cable if preferred. Disconnect the grey and pink wires from TB4 and
connect the separate cable wires instead
2. For connection to IS15 instruments refer to revision C or later of the IS15
NMEA manual.
3. On AP45 and AP9MkII – Mk3 installations you need the compass connector
kit part no. 22088413. Connect the AMP connector (J2, J5) from the kit as
per Figure 3.
INSTALLATION
The RC37 contains a magnetic fluxgate sensor and great care should be taken when
deciding the mounting location.
Figure 1 Mounting

RC37 Rate Compass
07.06.04 2 20221370A
Select a location that provides a solid mounting place free from vibration and as close to
the vessel's centre of roll and pitch as possible, i.e. close to the water line. It should be
as far as possible from disturbing magnetic influences such as engines (min. 2 meters),
ignition cables, other large metal objects and particularly the autopilot drive unit.
The compass must be mounted horizontally. When the compass is deck mounted and
equipment connected to the compass has no off-set compensation, provisions should be
made to allow for mechanical alignment. In that case the compass must also be mounted
with the cable gland pointing aft.
Use the supplied mounting kit and drill holes through the centre of the slots.
Note ! The compass face plate on the RC37 is the TOP. Never mount it upside down!
On steel hull boats it should be mounted on a non-ferrous pedestal approx.
0.9 m (3 ft.) above the wheelhouse.
ELECTRICAL CONNECTIONS
RC37 is wired for NMEA connections, See Figure 2. When connected to autopilots it
must be rewired as per Figure 3 to provide heading output on sine/cosine format (swap
the wired and the unwired terminals) A separate cable gland is supplied for a second
cable that can be used for additional heading output on NMEA0183 format. See Figure
2.
Electrical connections NMEA0183 output stand alone compass
Figure 2 Stand alone NMEA compass

Installation instructions
20221370A 3 07.06.04
Electrical connections AP45/AP9MkII/AP9Mk3
Figure 3 RC37 connection to AP45/AP9MkII-Mk3
CALIBRATION
Note ! When connected to an IS15 system as per instructions, use the IS15 calibration
procedure.
The calibration is carried out using the following procedure:
1. Switch on the autopilot to supply power to RC37, or use a separate switch if it is a
stand alone compass.
2. Make two 360 degree turns to starboard within 5 minutes
after switch on. Ensure smooth and slow movements. A
minimum of roll and acceleration will give the best result.
Use 60-90 seconds each turn and make sure the boat passes
3 times through North (see figure). As soon as north is
passed for the 3rd time, there will be a confirmation in the
autopilot display (see below).
•Provided you have an AP45 with software version V1R3 or V1R4 (latest), you
will read "Fluxgate compass compensated" in the info display when the
calibration is completed. Press the alarm button to reset. There will be no
confirmation in the display if the AP45 has a software revision earlier than V1R3.
•On AP9Mk2 and Mk3 there are no verification codes. However, when passing
through north for the 3rd time, the course display shows 045 for a short moment
(less than a second).

RC37 Rate Compass
Simrad Egersund AS
P.O. Box 55
N-4379 Egersund
Norway
Telephone: [phone]
Telefax: [phone]
ALIGNMENT (Offset)
Carry out the calibration procedure, and then steer the boat on a known heading or
bearing. Slightly turn the compass until the correct heading readout is displayed.
Tighten the screws. IS15 has a built in off-set correction, please refer to the manual.
Note ! If you sail more than 15-20° north or south of the latitude of your last
calibration, the calibration procedure should be repeated. Calibration data is
stored in the RC37 and will only be deleted when a new calibration is
performed.
TECHNICAL SPECIFICATIONS
Heading output: ........ Serial and analogue
Output format: .......... NMEA183 10x/sec. and sine/cosine.
NMEA data:.............. $IIHDG,x.x,m*hh<cr><If>x.x=heading, hh = checksum
Analogue data:.......... Sine/Cosine ±2V, 2.5VDC reference.
Accuracy: ................. <1.25°rms
Repeatability:............ <0.2°rms
Calibration: .............. Automatic
Roll & Pitch: ............ ±35°
Supply:...................... 10-29 VDC, 1 W
Temperature:
Operation:.......... 0 to +55°C (+32 to + 130°F)
Storage:.............. –30 to +80°C (–22 to +176°F)
Protection:................. IP56
Mounting .................. Deck or bulkhead
Cable supplied: 15 m (49 ft.) with open end
Note ! RC37 uses the same software as the RC36 Rate Compass, hence the software
label is marked RC36.
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