Notes on Upgrading White Knight’s Navigation Systems

Starting point.

When we bought our Contessa 32 White Knight her electronic navigation instruments were largely original. Some were not working; others were becoming unreliable. So upgrading the navigation systems was a significant part of our early refit budget.

White Knight’s Navigatorium was well appointed for its time. The teak faced chart table was still in good condition, regularly polished and covered with a canvas cloth when not in use. The crew very quickly learned and adopted the draughtsman’s creed of not to use it for cooking, drinks and eating.  The chart locker under the desk lid gets used for storing many other small things people want to “put out of the way but handy”. Regular rummaging, spring, summer, autumn and winter decluttering is gradually getting the melee under control.  Mounted above the chart table was a pair of Stowe Navigator display units and an antiquated Furuno GPS. The original VHF Radio predated GDMS but had an external speaker in the cockpit which was not working.  A NASA Navtex was out of sight in the quarter berth and the original (and much modified) switch panel beside the navigator’s seat. The domestic and engine batteries were secured beneath the Navigator’s seat with the selector switch on the front panel. Safety equipment including grab bags, flare packs and lifelines get stowed in the locker under the chart table.

Starting point, Chart table with 1970s Stowe instruments, 1980s VHF and 1990s Feruno GPS

The compass is a Plastimo Contest bulkhead mounted with an internal light. It worked, the lens was clear, and it seemed to be reasonably well adjusted when checked. There was no need to change it.

The electronic instruments were a set of late 1970s Stowe Navigator series with depth sounder, log and wind sensors, a pair of displays at the chart table and repeaters including a wind direction display in a pod over the main companion way.  The wind instruments did not work and there was no obvious fault in the wiring. The depth sounder worked well with an in-hull sensor in the forward locker. The log also worked for speed but kept losing its memory of overall distance covered.  The through-hull paddle wheel sensor was mounted to starboard of the leading edge of the keel in the heads compartment.

Starting point, Pod with 1970s Stowe depth, wind and log. Almost new Raymarine Chart Plotter AKA “The Mutts”

The Furuno GPS had been set up in the 1990s to link to a laptop and link to the tiller pilot however the system belonged to a bygone stage of GPS development and had been abandoned in-situ, superseded by Jeff’s chart plotters. For many years Jeff had sailed White Knight with a handheld Raymarine GPS 40 with a small colour chart screen mounted on a small bracket by the hatch. He had upgraded to a Raymarine A Series 9 inch Chart Plotter which he mounted on the sliding hatch. It was in prime position to be seen from the helm and block the view of the Stowe instruments in the pod. The whole electronics system predated any form of network like NMEA 0183.

What do we really need?

I have never been a fan of being totally reliant upon electronic equipment at sea. My “hierarchy of need” is

  1. First and foremost: Can I sense it myself without any instruments at all i.e. sight, sound, smell, taste or feel? In familiar water one rarely needs anything else. Polynesian navigators crossed oceans finding tiny islands without artificial aids to their navigation, but with huge skill and depth of oral knowledge. 
  2. Stand-alone easily repaired aids to senses: burgee or windex, magnetic compass, hand bearing compass, sight tube for fuel level, lead line, clock, barometer. Backed up with paper charts, almanacs, pilot books, plotting instruments and good data on the boat’s performance. I am not yet confident to navigate with a sextant but do enjoy playing with one.  Yachtsmen successfully cruised the globe with this level of navigation aids well into the later part of the 20th century. 
  3. Stand-alone electronics: echo sounder, I loved the old Seafarer flashing diode echo sounder because it was so simple, robust, reliable and easy to repair. Like an analogue watch, one can gauge the depth at a glance without having to read a digital display.  A transistor radio for time signals and weather reports. Handheld GPSs with spare batteries. Handheld VHF radio. This was our standard set up for many years on our Cornish Shrimper Daisy when sailing the Irish Sea and Clyde.
  4. A Hardwired Networked system:  To minimise the risk of a single failure bringing down the whole network in designing the new hardwired system, I made sure that each of our main networked instruments can either work totally independently or revert to a standalone aid if all the others fail.
  5. Wifi / Blutooth: data to remote displays, laptops, I Phones, I Pads, Tablets, Smart Watches etc. Definitely not “Essential” but fun to play with for those who are so inclined.

After several years of chartering boats and sailing Daisy I have built up my personal carry on board navigation tool bag. It comprises; handheld VHF radio, Garmin 72 GPS and Iris 50 hand bearing compass, pencils, eraser, dividers, Bretton plotter and pocket logbook. It also includes Imray charts, pilot books and almanacs. In addition we all had our IPhones and an I Pad each loaded with Imray chart plotters, tide data and various weather forecasting apps. I have also dabbled with a notebook computer with Sea Clear and Open CPN chart plotters linked to a blutooth GPD module. So if all else failed this bag of tricks could get us through.

Round 1: Initial Upgrades and replacing what did not work

Our first upgrade was to remove the old VHF radio and the Furuno GPS and replace them with a new B&G V60 GDMS VHF radio with built in GPS and AIS receiver. The existing cabling and aerial were tested and found to be OK. The external speaker did not work so was left for another day. We carried a handheld VHF radio in the cockpit.

There is a lot of debate about where to fit a chart plotter. Jeff’s preference was to mount his to be visible in the cockpit on the companionway hatch under the spray hood. This makes a lot of sense for shorthanded sailing particularly in the cooler wetter climes of Scotland and the west coast. Others prefer to keep their Chart plotter at the chart table and rely on a tablet or I pad in the cockpit. This may be OK for larger crews and in the warmer climes of the Mediterranean or for soft southern navigation.  An IPad would not last long exposed to Scottish or Welsh rain no matter how well ruggedized.  We kept with Jeff’s choice.

Crossing the Firth of Lorne in fog. AIS on the radio gave a crumb of comfort.

This set up served us well for our first cruises around the Inner Hebrides and into the Clyde.

Round 2: Building the hard wired NMEA 2000 Network

With White Knight ashore for her first major winter refit for 20 years and with the mast down we were able to check out the aged Stowe wind sensors. We could also start to plan our new instrument layout and how we could start to link them together. First priority was to link the AIS to the Raymarine Chart Plotter to display targets on the one screen, also to be able to cancel the alarm from the cockpit. If this had been the limit of the improvements, it could have been achieved with a NMEA 0183 link between the VHF and the Chart Plotter. But the Chart Plotter had a much greater range of untapped functionality and we had also made some savings in the budget so we decided to take the plunge and install new wind, depth and log sensors to link to the Chart Plotter.

To help plan the network I drew out a single line diagram of the existing system and then started to plan in various upgrade options. Key considerations at this stage were;

  • The positions of each of the sensors on the boat (Mast head, through hull fittings, GPS aerials, engine sensors) 
  • The locations where we would need to access which data (chart table, cockpit and elsewhere)
  • Also, what systems may in the future be driven from the network e.g. tiller pilot.

Using this diagram I was able to plan out cable routes, lengths and connection points to drop cables.

NMEA 0183, NMEA 200 or Raymarine Seatalk? NMEA 0183 is gradually being superseded by NMEA 2000 protocol instruments. The Chart plotter and the VHF supported both NMEA 0183 and NMEA 2000 but since we were primarily replacing the analogue Stowe Navigator instruments it made sense to go straight to a NMEA 2000 network. Raymarine Seatalk is essentially a NMEA 2000 compatible data stream but uses slightly different connectors between the instruments and the backbone. All other manufacturers use compatible “Micro C” connectors.  Our Raymarine chart plotter came with a Seatalk to Micro C NMEA 2000 interface cable so we decided to adopt NMEA 2000 backbone and connectors as our standard for the network.  A B&G combined depth, log, and wind instruments with a Triton2 multi-functional display (MFD) and a basic NMEA 2000 backbone package was on special offer as a winter deal from Cactus Marine at a relatively attractive price.

I decided, for the initial installation, to keep the Stowe depth and log sensors and chart table displays as an independent back up system.

Over three weekends and a Covid Lockdown I installed the basic network. The first weekend was spent removing the pod and Stowe repeaters, pulling back all the disused cabling and pulling through the basic backbone cabling.  A fiddly job best done without anybody else around to distract or hear the language. By the end of the first weekend I had connected the Chart plotter to the VHF and proved the AIS interface worked. The power of the Chart plotter as an all singing MFD was demonstrated. We rechristened the Chart Plotter the “Mutts Nuts” in deference to Jonathan’s dog who had recently been castrated.

The next weekend was spent installing the new sensors. To mount the Airmar combined depth and log in the Contessa’s deeply vee’d hull we bought a specialist bronze through hull fitting from Jeremy Rogers Yachts. Boring a 50mm diameter hole vertically below the water line was a big step. It then took quite a bit of rasping and cleaning to make a good snug fit with roughened sides ready to receive the fitting and a bead of marine epoxy to bed it in. Being a cold day the epoxy took several hours to cure and had to be propped from below. Meanwhile Ian & Jonathan tackled the wind instruments. The old Stowe sensors were well and truly corroded on. But with oil, heat, brute force, ignorance and a grinder the screws were eventually removed.  The cable was pulled back along with a mousing line ready for the new cable. The new mast head mounting bracket was relatively easy to fit. But the cable connectors would not fit down the mast track. B&G’s technical department were not able to advise what size field connectors we would need to replace them. They were smaller than the NMEA200 standard “Micro C” connectors. Eventually, running out of time, we cut off the lower connector with about 300mm of cable as a tail, as this would need to be reconnected inside the cabin, we had time and spare cable to work out a suitable fix.   The new cable slipped easily down the mast.  Jonathan took the pod, Mutts and Triton2 MFD home to make a new deeply varnished dashboard to take the new instruments.  A few days later we entered the first Covid Lockdown.

With lockdown eased it was only a few hours work to refit the pod, pull through and secure the backbone cable for the Triton MFD and the Mutts. Then tidy up the rest of the cabling and make the final connections to make sure it all worked. The through hull fitting was wet tested as we launched. No leaks, whoopee! and the depth looked reasonable, even better. Reconnecting the cut wind sensor cable was slightly trickier. All the advice was to use a field connector, if you can get one, even so it would be tricky. My brother, an electronics fiend, initially suggested using “breadboard” and soldering the very fine wires. But then suggested the wonderfully named “heat shrink butt connectors” as a more water-resistant solution and easily sourced via Amazon. I also brought some larger diameter heat shrink rope end protector to add an additional layer of protection over the butt connectors.  An electric hot air paint stripper provided sufficient heat to do the job.  All cabled up and switched on, the network all worked together.

Varnished Dashboard with linked instruments displaying on MFDs Triton and “The Mutts”

Calibration took place through our shakedown cruise around Loch Fyne. The depth was initially calibrated to match the Stowe depth gauge. The set point Zero was a seemingly random depth somewhere between the water line and the sensor head. We quickly found that the keel depth was 1.4m below the set point. Standing instruction to all helms “maintain a minimum 2m on the depth sounder”.   Initially the log over read by 30%, however the Triton2 includes a calibration to allow the through the water speed to be calibrated to the GPS. A few runs at slack water up Loch Fyne gave reasonably consistent results. We checked the log again using the distance markers off Arran. Wind angle seemed to set well right from the start. We had no way of doing an accurate measure of wind speed at the top of the mast but the readings seemed about right when checked against a hand held anemometer at deck level.  

Calibrating the Log Loch Fyne

With all the instruments talking with each other, reasonably calibrated and good displays for the helm. The Navigator was in nerd heaven for our summer cruises and delivery trip from Scotland to North Wales.   The Triton2 display next to the chart plotter was scrolled through all its many displays. Favoured display on passage was GPS position, course to next waypoint CMG and ETA.  Closing the coast the combined depth and speed display was favoured. The wind displays were called up regularly, particularly wind speed history as squalls came through. The chart plotter with AIS overlay provided reassurance particularly when visibility decreased. A short coming with the Raymarine A Series touch screen display emerges in wet weather when the touch screen controls stop working. MFDs with hard controls like the B&G Triton2 and Zeus do not suffer with this problem. 

The Navigator’s tools were stowed in a teak rack for the pencils and dividers. A teak box for the sighting compass was secured where it could be reached from the cockpit and a teak binocular box was also secured beside the chart table.  

A paper deck log (Aldard Coles Pocket Logbook) and marked up Imray passage chart were kept on the chart table along with the passage plan and an A4 spiral bound note book for radio traffic, shipping forecasts and rough notes. The fair log is kept in an A4 loose leaf folder. At this time there were no shelves suitable for A4 books and folders so they were kept in the Navigation bag, or added to the melee in the chart locker.

With this set up we completed our second summer of cruises and the delivery trip from Scotland to North Wales.

Round 3: Chart Table

With the helm adequately supplied with data it was time to consider the next round of improvements to the navigation systems. At the chart table the Navigator was being left without access to data as the Stowe displays started to become unreliable.  The small display of GPS and AIS data on the VHF was adequate but not easy to read with wet glasses and a lively motion. As a quick fix the new VHF had initially been mounted on top of the box with the Stowe displays, all of which was held to the bulkhead with a single screw. All rather wobbly and annoying. We were also finding that the Navigator was as likely to nip below and work standing at the end of the chart table as to sit facing the desk. So visibility of displays needed to work both ways.

One of my pet hates is loose fittings and dangling cabling, especially around a Navigation Station. The Contessa being a 1970s design tends to heal at 20 to 30 degrees when sailing to windward “in the groove”.  Moving around the boat safely under these conditions requires reliable grab points. As a rough guide anything a crew member may grab to prevent a fall needs to be secure, and all loose items need to have secure stowage. So in tidying up the Chart table, cables needed to be managed out of sight and secured. Accessible stowage was also needed for the charts, log books and A4 folders.

I started by relocating the VHF under the side deck to the side of the chart table. To replace the Stowe displays I got another B&G Triton2 MFD on offer from Cactus Marine. This was mounted in a marine ply box under the VHF which also kept the NMEA 2000 connectors and cables safely secured out of sight. In this location the MFD is clearly visible to a Navigator either standing at the end of the chart table or seated. The box also holds the chart table flexilight. This arrangement also kept enough space for A4 folders, almanacs and pilot books to be stowed in the cubby hole at the side of the chart table.

Tidy and Modernised Chart Table

Round 4: Going Wi-Fi

A feature of the Raymarine A series chart plotter is that it can be linked via wifi to an IPhone using the RayView app to replicate the screen or to an IPad using the RayControl App to control the display remotely. But, this could be confusing to a helm piloting up a narrow channel while the Navigator was using the app to scroll screens and do some other navigation tasks.

Giving the Navigator independent access to the NMEA data would be an advantage. The old Furuno GPS has included a RS323 to USB link to a laptop which, with suitable software like SeaClear, could be used as a chart plotter and possibly even control the tiller pilot. Electronics have advanced significantly in the 20+ years since the Furuno system had been installed on White Knight. Open CPN seems to be the laptop navigator’s weapon of choice these days combining raster chart data with AIS overlays and a wide range of navigation functions. Tablet computer Apps are now widely and cheaply available that can display all the NMEA data in a range of formats. Navionics and Imray Chart plotter apps have the full functionality of their Chart Plotter MFD equivalents.   Programming geeks are developing new functionality all the time. Self-writing logbooks, data analytics, push button polars, the geeks are at work. All that is needed is a way to link the NMEA network to the laptop or tablet.

I chose an Actisense W2K-1 NMEA2000 to Wi-Fi Gateway again on offer from Cactus Marine. This rugged device is little larger than a credit card, about 10mm thick and includes a micro SD card which depending on how it is configured can record about 16 days of NMEA data before over writing the oldest data. Using a NMEA2000 T piece connector it can be easily added to a NMEA200 network. The Wi-Fi access is secure and password protected but does not connect to the World Wide Web. 

With a couple of minutes work sorting out the configurations I had Open CPN running on my old Netbook with GPS and AIS data from the NMEA network. I also setup my IPad to stream the NMEA data into Imray Instruments app. This app allows the user to configure their own instrument panels from a wide selection of options. With the Wi-Fi I can access this from anywhere on board.

Removing the Stowe instruments from the bulkhead leaves room for an IPad holder above the Chart table, close to a USB charging point.

Round 5: Where Next?

AIS Transponder: For the sailing we have done to date with White Knight the AIS Receiver built into the B&G V60 Radio has certainly been a valuable aid to navigation. We have not (so far) felt the need to be transmitting AIS data in the relatively quiet waters of the West of Scotland and a Covid Locked down Irish Sea. It is a real pain coming into a marina with so many AIS targets of parked yachts alarming and distracting the helm from the job in hand. Part of the joy of sailing is to get away from it all. Having family able to track our every move and get worried if they can’t see us on their mobile phone 24/7 is a mixed blessing that would not have occurred to sailors even a few years ago.  

Moving to the busier waters of the southern Irish Sea and English Channel, the safety driven argument for an AIS Transponder increases rapidly. Many vessels are now relying more and more on AIS rather than visual lookout and radar to spot potential collisions.  The mixed blessings of the family Marine Traffic watchers pale into insignificance when compared to 70,000 tonnes of bulk carrier travelling towards one at 20+ knots.

Had we known that the B&G V60B with built in AIS Transponder was coming we may have held off, but decisions are always made with what is known at the time. “If only” is after all the saddest word combination in the English language. Good NMEA 2000 Class B AIS Transponders are now available for about £600, with a VHF splitter these can be wired into the main VHF aerial. Alternatively a separate aerial would reduce the reliance on a single point of failure.  I will probably go for the splitter to get maximum range from the mast head aerial with the boxed emergency aerial kept in the chart locker just in case.

MOB Devices and Personal Locator Beacons are amazing devices in extremis. I would prefer myself and my crew not to go over the side and get into that sort of situation in the first place. A controlled dose of the fear that turns brown and smelly will I hope teach the crew to move more carefully and clip on so as not go OB.

Back to basics. We recently had an interesting exchange on WhatsApp after posting a photo of us passing through the notorious Swellies in the Menai Straits. The eagle eyed viewer spotted that the Chart plotter was in plain sight and commented that he thought we would have been glad to have it on. On the contrary we were not using it. We were navigating through these treacherous waters using the same transits described by the Caernarfon Pilots for bringing far bigger vessels through between the rocks and under Telford and Stephenson’s mighty bridges. 

Just as when driving down a motorway, I spend far more time watching the road and other traffic than glancing at the dials, these amazing aids to navigation are just that, aids.

Mark One Eyeball Navigation. Following the Transits Through the Swellies. West Abutment of Stephenson’s bridge in line with the small day mark on Prices Point gives a clearance transit for the Platters, and the Swellies Rock
Under Mr Telford’s Menai Suspension Bridge

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