With the advent of Wifi, NMEA 2000 and new ‘wide screen’ technology, our system was been upgraded to take advantage of these qualities. This included faster data transfer streams between instruments and enhanced redundancy, with ‘power saving’ manual switching.
Before we go further, IT WILL BE A LOT EASIER following this brief with a pen and paper, or even the electrical diagram shown below and a switch diagram. It does get confusing, but once drawn, shows all the redundancy aspects of the wiring. There are FOUR Switches that control all the electronics and that starts in the section 'Power Saving Switches' (namely switches A, B, C and D).
Initially, the reasons for changing the switch wiring was to effect three key areas; situational awareness (AIS), redundancy and power saving. We have had periods when sailing where items such as the transducer is not required, or even certain sail instruments where not required and given that many of these components have large power requirements, we had an electrical rethink.
Additionally, the current wiring did not allow for failure of components, if the chartplotter (or MFD - Multifunction Display) went U/S, we lost all forms of electronic navigation and the process of quickly checking wiring, was near impossible given the hiding of all components during the initial install.
We have since moved the navigation wiring to a very accessible position in the saloon (which we call ‘the navigation wiring panel’ in this document), where circuit breakers and wiring can be easily checked and covered.
Power Saving Switching
While the vessel was underway, smart switching was installed to reduce the drain on battery reserves when one or more components were not in use (or needed). With the use of a Laptop (or iPad) and Brookhouse Multiplexer (MUX), various areas could be de-energised while allowing for basic navigation and autopilot use.
The major navigation power consumers are:
- Raymarine DSM300 (P60 Transducer),
- Raymarine MFD (C90W Multifunction Function Dislay),
- ICOM VHF Radio (ICOM 422), and
- Raymarine Wheel Pilot Autopilot (Raymarine ST6002).
To provide options to isolate components (when not needed) and build in redundancy, helm switching is broken down into four areas, grouped as our 'Power Saving Switches':
- ‘Autopilot’ Switch,
- ‘C90W’ Switch,
- ‘Sail Inst. and MUX Only’ Switch, and
- ‘Radar’ Switch.
NOTE 1 : To best follow the switching below, we would strongly suggest using the 'Data Transfer Diagram'.
NOTE 2 : The dashed lines represent the various groups of electronics, including the four 'Switching Groups' mentioned above.
NOTE 3 : MUX - refers Brookhouse Multiplexer, and MFD - Refers Multifunction Display (C90W).
A/ Autopilot Switch
This switch operates the three major components of the Raymarine Wheel Pilot package:
- Raymarine Autopilot Head,
- Raymarine Wheelpilot (not shown in diagram), and
- Raymarine Autopilot Computer.
This also has its own fuse located within the Raymarine Autopilot Computer unit itself. Refer to this document ‘Electrical Diagram – Switches & Fuses’ for more detail.
Autopilot – least power position.
In its simplest form (with no other 'Power Switches' ON), the Autopilot Switch allows basic autopilot use in the ‘auto mode’ (that is without the tracking function). This is the least power position with basic autopilot assistance.
As shown in the diagram, this does not provide depth, sail instruments or navigation instrumentation. This is our barest form of autopilot use.
To engage the ‘tracking mode’, the autopilot will require heading and GPS data. This can be provided three ways:
- Switch the Power Switches (Sail Instruments and Brookhouse Multiplexer switch) - ON, and use a laptop (with its navigation data), OR
- Switch the Power Switches (Raymarine C90W switch) - ON, OR
- Switch both the Power Switches (Raymarine C90W and Sail Instruments & Brookhouse Multiplexer switch) - ON. (No laptop navigation required).
Failure of the ‘Autopilot Switch’ function
Electronically, there is none, the autopilot will be unserviceable. BUT...the autopilot clutch can still be engaged. This is a manual gadget anyway and will hold the helm wheel, so very basic autopilot control is available with visual monitoring of your course and correcting as needed.
B/ C90W Switch
This switch operates the major components of the Raymarine Multifunction Display package:
- Multifunction Display/Unit (Raymarine C90W) ,
- Depth Transducer (DSM300 and P60 transducer),
- AIS Unit (ICOM 5000), and
- Radar power to the Radar Switch (not to be confused with the other 'Power Switches - Radar Switch).
The C90W has three fuses on the navigation wiring panel, AIS, Radar and C90W. Refer to this document ‘Electrical Diagram – Switches & Fuses’ for more detail.
Multifunction Unit (C90W) – least power position.
In its simplest form (with no other switches ON), the C90W Switch allows:
- Navigation information,
- AIS information,
- Depth Information (on the Raymarine C90W Multifunction Unit only), and
- GPS position.
This is the least power position for this unit and switched on its own, it will not provide:
- Sail instruments power, and
- Radar (until the Radar switch is switched on).
To engage the autopilot, switch the Autopilot Switch to ON. This will provide basic autopilot functions in both ‘auto’ and ‘tracking’ modes.
Failure of the ‘C90W Switch’ function
Failure of this unit can be supplemented by a Laptop and use of the ‘Sail Instruments & Brookhouse Multiplexer Switch’ (refer to that switch function for further detail). However, depth and AIS will then not be available.
C/ Sail Instruments and Brookhouse Multiplexer (MUX) Switch
This switch operates the Sail Instruments and GPS electronics:
Sail Instruments (Raymarine ST60 Wind, Speed and Depth gauges),
MUX (Brookhouse Multiplexer),
GPS Receiver #2
(Humminbird GR16 - to the Brookhouse Multiplexer for GPS backup to the C90W), and
GPS Receiver #3 (Navman 1240 GPS – to power GPS position function on VHF Radio).
This switch has its own fuses (Sail Instr. and MUX) on the navigation wiring panel. Refer to this document ‘Electrical Diagram – Switches & Fuses’ for more detail.
Sail Instrument & Mux – least power position.
In its simplest form (with no other switches ON), the Sail Instruments and Brookhouse Multiplexer Switch allows:
- All sail instruments to be powered (no depth function),
- Laptop plotter/navigation information to be made available (if installed),
- Brookhouse Multiplexer,
- GPS #2 - Hummingbird GR16 (external), and
- GPS #3 - Navman 1240 (external).
This is the least power position and switched on, it will not provide:
- Multifunction C90W,
- AIS, and
Why so many GPS’s
We had found that GPS’s do have a tendency to fall over. Given that our new MFD had an internal GPS and that that GPS could be shaded at times given its installation position, a back-up would be a strong advantage. We have three GPS heads in total by default:
- GPS Receiver #1 - within the Multifunction Unit (Raymarine C90W - internal),
- GPS Receiver #2 - Hummingbird GR16 (external), and
- GPS Receiver #3 - Navman 1240 (external).
GPS Backup – primary transfer
Using the Brookhouse Multiplexer (MUX), we were able to provide this GPS redundancy. The Brookhouse MUX has a great feature that assesses the ‘GPS related data strings’ at regular intervals and when it finds the data missing (i.e. primary internal Raymarine C90W ‘GPS strings’ not being transmitted), it automatically switches to the alternate GPS (in our case, the Humminbird GR16). We are yet to get it to do this automatically, but can be done manually.
The Humminbird GR16 then continues to supply GPS data until the ‘primary GPS strings’ are again sensed. The Humminbird GR16 is then reverted back to standby via the Brookhouse MUX.
To provide GPS back-up, the following switches must be on as a minimum:
- C90W, and
- Sail Intruments & Mux.
Since installation, the GPS receiver units have taken off and in some cases, being reduced in cost. If your system has any form of 'wireless/bluetooth' integration, the cheaper portable units may be right up your alley. After all, its only as a backup that extra units may be required. Many can be wirelessly connected to iPads and iPhones and wirelessly forwarded to your MFD's.
Wireless and bluetooth technology is by far the technology of the future and should be on the 'serious consideration' list. This is however another topic.
GPS Backup – secondary transfer
Should the C90W be switched off for any reason, the Brookhouse MUX will sense a loss in GPS data (as detailed above) and automatically allow Humminbird GR16 data strings. This can then be used with laptop connection and navigation software, allowing the autopilot to navigate without using the Raymarine C90W.
The last line of defense is with the Navman 1240 GPS. This is independent to the other navigational systems and linked to the ICOM VHF RADIO only allowing GPS position data readings (off the ICOM 422 VHF radio face). It is not linked in other way to the other navigation systems and cannot be used with the autopilot directly.
Failure of the ‘Sail Instruments and Brookhouse Multiplexer Switch’ function
- Failure of this switch will stop Multifunction Unit GPS back-up (i.e. Humminbird GPS power is lost).
- GPS data to the ICOM VHF radio (i.e. Navman 1240 power is lost).
- NOTE: the power to the ICOM VHF radio itself will not be lost, this is a separate power switch.
D/ Radar Switch
This is self explanatory, for independent operation due to its power drain and simply supplies power to the radar unit.
Facts, Figures & Further reading:
Manufacturer website: Raymarine
Manufacturer website: ICOM
Manufacturer website: Brookhouse