Instrument Failure !

(Warning tech blog – may not be of interest to many)

During Vicky’s visit, we noticed, upon leaving Z’Abricot that the depth sounder was giving erroneous readings, the wind indicator had to be rebooted a few times and the NMEA information (local network) wasn’t giving any data at all. The depth and wind soon sorted themselves out but the NMEA information didn’t.

So, for those interested, Stargazer has a bespoke electronics system – well, she would, wouldn’t she… The system comprises two independent chart plotters, one radar, an AIS system a multi display, a VHF incorporating AIS, an autopilot and Tacktick instrument displays. Without going into massive detail the system was set up to still provide data if one part of it failed. For example, the two chart plotters are separate from each other. Wind and depth are separate from the NMEA data. There are two sources of AIS and the radar inputs directly to the main chart plotter.

Having satisfied ourselves that wind and depth data (which is analogue) were fine, we were faced with no NMEA information at all. This means speeds, headings, courses to name a few weren’t there. First I said to the mate, no need to worry, we have depth and we regularly check this against a rope lead line. Being old school (as I am) as long as you have depth you are OK, the rest can be estimated or worked out, especially if you have old style paper charts, which, being old school, of course we do. Nevertheless, not having data that you used to have was annoying. So I enlisted the mate’s help and together, we eliminated various things i.e. we knew the main plotter was OK, we knew the second plotter could receive data and we knew the Tacktick NMEA transmitter was OK. All the various components were receiving a good 12v supply and the Tackticks batteries and solar panels were in good shape.

The only thing left to do was to chase the wiring around and see where any connections may be broken. Sounds simple – but my oh my, what a palava. Things had to be dismantled, panels had to be removed wires had to be chased where they had changed colour after a join. On and on it went for nearly four days. Using the ships multi-meter, a decent length of small wire and a pen knife, we followed as many wires as we could. I’d scrape a bit of insulation off in places and we’d check continuity with the meter and everything seemed fine. We were getting a bit despondent and beginning to think the problem must lie in the Tacktick NMEA transmitter after all. (Very expensive and impossible to get out here!) The final thing to do was check below the steering pedestal where access was a bit of a nightmare – that’s probably why we’d left it until last. Once accessed, lots of sand fell out of a few crimped connections and one connection just fell off. How sand got in there, I’ve no idea, other than it is extremely windy out here and there always seems to be Saharan sand in the wind. A temporary connection made and lo and behold, all our NMEA data came back to our great delight. I remade all the connections fastened them up and protected them; the whole system being better than before in my opinion. Plus we now know where all the wires go and what they do – priceless!

The final thing to do was to reinstall all the panels and put all the gear away – can I have a beer please I asked the mate? The reply – only when you’ve finished…

I’ll leave this with one final point. Stargazer’s system is bespoke as I imagine a lot of boats systems are, especially older ones. If we’d have called out a marine electronics expert, they wouldn’t have known where to start either. It would probably have taken days and cost a small fortune to do what we did. So, if anyone reads this who has a boat, I’ll offer my advice on a take it or leave basis: but if I were you, I’d find a day or two and follow all my wires, draw a diagram and clean up/replace all my connections and then – have a beer J