Grounding 12v system

[Ozzie]

Thanks Peter, so much confusing stuff on the web re electronics not just boats and caravans but now houses on solar. We have just had solar panels installed on our roof and the finer points of installation and commissioning raised a few questions. We got different interpretations from the company, their contract leco, who installed the isolating switch, their installation leco and our power supply authority who had to reconfigure our meter.

Go figure.

The company wanted us to post feedback on their advertising web site. After I told him about all the confusion he passed

Re my boat, I’m lucky I have a fair bit of space around my mooring but increasingly it’s becoming stacked with floating gin palaces who although they are not connected to shore power probably have a fair chunk of a house battery or two and some with solar. Could that create any issues with electrolysis for my boat ? I still have the anode I bought 16 years ago to try and fit to the swing cb before I abandoned the idea. If I ran a wire from the swing keel pivot bolt and then attached that to that anode and hung it over the stern while on the mooring would that prevent continued degradation of my zinc gal cb. Or if if was an issue would the cb have already dissolved

[Peter T]

Hi Ozzie, With the electrics set up that you have, I wouldn't bother about it. It is possible to get some stray voltages from other boats depending on how well they have sorted out their electrics, but the risks are fairly low unless you are as I said in a marina and very close. On a 38 ft steel boat we had, I was able to measure 4.5V between the prop shaft and the hull of the boat causing obvious problems.( where you have a voltage drop, you have currant flowing causing electrolysis). We overcame that by shorting the two out with a jumper lead whilst the boat was not being used. You just had to remember to take it off before running the engine. This only happened whilst the boat was in the marina.
Connecting to your centreboard bolt will do nothing good but could make it worse as the centre board bolt is insulated from the actual centre board because of the bushes that the bolt goes through but it is close to the centreboard plate which could lead to a small leakage of potential through dirt/wet between the bolt and the plate (ie a resistive path. Where there is a measurable resistance, then voltage can form across that resistance). In this case, it would be better to not connect any potential to the centreboard bolt leaving it without any +ve or -ve potential. Hope this makes sense.
Regards Peter T

[Ozzie]

Thanks Peter, well explained. I hoped I was ok . I often wonder about the boat when sitting out on the mooring during storms but as I don’t have any form of electronics on board their is not much to fry, no radio not even fm . Only things I have electronics wise like my anemometer, portable speaker go home In my sailing bag. I’m also lucky to be surrounded by taller masts these days.

Thanks again for the comprehensive explanations on this thread.

[Peter T]

That's great Ozzie, Just relax and enjoy you boat. The worst case I knew of was at Port Dalrymple yacht club quite a few years ago, there was a Hood moored which had electrics including a depth sounder mounted through the hull. It got struck with lightning via the mast which blew a hole through the depth sounder on its way to earth ( path of least resistance) All that could be seen of the boat was about two feet of the top of the mast at low tide. What a disaster.
Cheers
Peter T