Instruments refusing to talk to each other

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Hardover
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Instruments refusing to talk to each other

Post by Hardover » Thu May 24, 2018 11:23 am

Some years ago now I was a fan of old landrovers. Part of the challenge of owning an old vehicle is working out the various bodges carried out over the years by previous owners. It seems that yachts can provide the same challenge.
Paka'a, our GK29, was raced fairly extensively over the last 15 years and has been fitted out with an extensive array of electronic equipment in her time. Most of it still operational with a few exceptions.
The old Garmin GPS appeared to have problems in obtaining a fix, the GPS repeater just read "no data available", the recently installed NASA AIS engine did nothing. The Standard Horizon DSC radio kept asking for a manual input of position and the Standard Horizon chart plotter worked intermittently then would show "signal lost.
Where to start?
The installation of the chart plotter in the cockpit had been a supreme bodge. Fixed at a drunken angle using oversized screws, no attempt to waterproof the cable entry points and a GPS ariel and cabling which had to be temporarily mounted in position on the pushpit every time we went out then returned to the saloon. An afternoons work put that right. What I did discover was that the ariel cable had been damaged during the original installation and kept shorting out. That was fixed and the chartplotter started working but still wasnt receiving data from the AIS or communicating with the radio and the GPS repeater still read no data.
The AIS appeared at first sight to be connected up in the right way. I discovered that this particular model requires its own dedicated VHF ariel. It cant operate on a split/shared cable. Where was the additional ariel? It had ariel cable connected but it didnt look like RG58 50ohm coax. Tracing the cable back I discovered the previous owner had decided to utilise the Garmin GPS ariel and had split the ariel between the two units using a domestic TV ariel splitter! At last we were making ground. Not surprising we were having problems.
The previous owner had obviously realised his mistake as there was a brand new Glomex VHF ariel sitting on the saloon shelf begging to be fitted. Mounted high up on the pushpit with low loss RG58 50ohm coax and the AIS began talking to the chartplotter. It also would provide an emergency ariel should the VHF radio mast head equipment be compromised. The original GPS ariel was given back to the Garmin and instantly the repeater functioned correctly as did the DSC radio. Result. Just have to get the speed log to work now but that can wait until the yacht is craned out at the end of the season.
I wonder what other surprises are in store for me!

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Re: Instruments refusing to talk to each other

Post by Fulmar433 » Thu May 24, 2018 12:05 pm

Well done sorting out the GPS issues. You may find the log is just full of crud. Most transducers can be removed whilst afloat if you have the blanking plug to stem the flow of water while you clean the paddle wheel. I fitted a new Raymarine ST60+ log a few years ago and the Airmar transducer fitting instructions advised painting the transducer with water based antifoul. After a bit of searching I found a product called Echo Antifoul that comes in a very small pot that cost me about £17 at the time. It seemed expensive for the quantity, but since I started using it I haven't had a fouled paddle wheel. I use a small art type paint brush to get into the paddle wheel and you have to make sure there are no lumps to catch and stop the wheel spinning. As for the price, I'm still using the same pot of paint, I think it's now been 5 years. Being water based if it gets too thick, just add a drop of water and mix it in. For trouble free log operation it has been extremely good value for money.
David Metcalfe
Fulmar 433 Jeddo
Lower Halstow, Kent

Hardover
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Re: Instruments refusing to talk to each other

Post by Hardover » Thu May 24, 2018 5:16 pm

Given that she hasn't been out of the water for at least two years that I know of, it's more than likely that the paddle wheel is bunged up! I don't think I have a blanking plate but I'll have a look around. Keep finding sll sorts of goodies tucked away in the odd corner. I'm assuming the transducer will be the one just outside the heads in front of the keel? Failing a blanking plate I may let her dry out between tides against some piling then have a look. I've read that flexing of the hull can be an issue with GK29's when drying out but Paka'a has steel plates fitted internally so hopefully that wont be a problem. It'll give me the opportunity to scrape her clean too.

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Re: Instruments refusing to talk to each other

Post by Fulmar433 » Thu May 24, 2018 8:18 pm

The log really needs an uninterrupted flow of water so more likely offset from the keel. If it's removable it should have a large hand nut on top, so the centre can be pulled upwards and replaced with a plug. The blanking plug will also have a matching hand nut to hold it in place.
David Metcalfe
Fulmar 433 Jeddo
Lower Halstow, Kent

Hardover
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Re: Instruments refusing to talk to each other

Post by Hardover » Mon May 28, 2018 12:52 pm

Came across this on the web :)

"I was as concerned as you about pulling this plug thing out of the bottom of my boat and replacing it with the blank one I found neatly chained to the inner housing. So I gave myself the best chance by firstly getting comfortable in the depths of the bilge, then I arranged for plenty of light on the subject from a leadlight and finally applied a dollop of Vaseline to the bit to be inserted and put it ready to hand.

With both hands I carefully eased out the offending transducer paddle wheel holder, the incoming water squirted about 2 ft in the air straight on to the 240v lead light, blowing the bulb to bits and knocking out the pontoon fuse which plunged me into darkness. The rush of water caused me to fall over and drop the the bung which was swept away.

Remembering the story about the little Dutch boy and the dyke, I held my hand over the hole as best I could and shouted for my wife, who was reading her book on the flybridge. Either at the end of her chapter or when she realised the boat was settling in the water somewhat she rescued me and apart from yet another cuffing round the ear for being such a prat everything turned out OK in the end.
But don't worry worse things happen at sea!"

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Re: Instruments refusing to talk to each other

Post by Hardover » Wed May 30, 2018 1:22 pm

found the paddle wheel transducer. It's located in the engine compartment, just aft of the gearbox and offset to the port, complete with a wooden bung tied next to it ready for use. Must admit I baulked at removing it given that it is criss crossed with cables. I can foresee things going badly wrong! It is the very last item that is left to fix but I guess it can wait.

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Re: Instruments refusing to talk to each other

Post by Hardover » Mon Jul 02, 2018 6:14 pm

Finally summoned up the courage to remove the paddle wheel transducer. Actually I've attempted it several times but it always refused to come free. This time it began to move! I started to pull it up and was expecting water to come gushing out immediately but it wasnt until it was fully removed thagt the water came gushing in. Must admit I was mesmerised by the sight of all that water and it took me a few seconds before I managed to insert the wooden bung into the apperture and stem the flood.
I was hoping to find the paddle wheel overgrown with weed and/or crustaceans but it was fairly clean. It appeared to move freely so I replaced it and started mopping up water - about 5 litres in all.

I've carried out a hardware reset on the display and am hoping maybe that will work but I've also ordered a replacement paddle wheel just in case. Slightly confused that the trip function is working ie it logs all the nautical miles covered but no speed shown. I'll keep working at it.

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Re: Instruments refusing to talk to each other

Post by Hardover » Sat Jul 07, 2018 2:10 pm

well the new paddle wheel did the trick. The old one looked OK and seemed to spin freely but obviously not enough. The brass pin was pink and snapped in two with very little pressure.
So, as of today all the electronics work as they should. Time to buy another yacht!

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