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Post by naughtyfox on Feb 11, 2018 20:46:35 GMT
Our hull surveyor suggested we get a galvanic isolator. I don't even know what they are, but have some idea that if your boat is in a marina and you're plugged into mains electricity all the time, it's something to help your hull not corrode.
Or is it in case a nearby boat in the marina has some electrical 'leak' and is causing yours to rust?
Who here has a galvanic isolator, and why?
Are we the only ones without one?
Anyway, we are happy we had our hull surveyed - not cheap, but 10-30 years peace of mind.
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Post by Telemachus on Feb 11, 2018 20:51:25 GMT
Our hull surveyor suggested we get a galvanic isolator. I don't even know what they are, but have some idea that if your boat is in a marina and you're plugged into mains electricity all the time, it's something to help your hull not corrode. Or is it in case a nearby boat in the marina has some electrical 'leak' and is causing yours to rust? Who here has a galvanic isolator, and why? Are we the only ones without one? Anyway, we are happy we had our hull surveyed - not cheap, but 10-30 years peace of mind. Yes we have one. It interrupts the shore power lead earth wire, allowing any significant voltage to get through, but disallowing just a volt or so. Sometimes the mains earth voltage isn’t the same as the local earth voltage and without a GI, current can flow down the earth wire causing hull corrosion. Of course, it is only relevant if and when you are plugged into shore power. If you never, or rarely, plug into shore power, there is no point in having a GI.
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Post by Deleted on Feb 11, 2018 21:36:39 GMT
If it is any good I'd be very happy for someone to explain why (in fairly simple terms).
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Post by Telemachus on Feb 11, 2018 22:03:41 GMT
It's cheap and fairly nasty, but it would probably work provided there wasn't a major electrical fault (short circuit to earth) on your boat.
They work by inserting some (normally 2 each way) back-to-back diodes in the earth line. The diodes need about 0.6v across them to start conducting, so any voltage difference less than that, they don't conduct. But of course with a fault situation, and mains voltage being applied to them, they would of course conduct and allow the RCD or MCB to trip.
So firstly, how many diodes in series each way? Normally 2 is a good idea, 1 isn't really enough. Secondly, since they will start to conduct if the earth voltage is more than 0.6 or 1.2v away from local earth, you want to know about it. So decent ones have LEDs or a meter that indicates when the diodes are starting to conduct (and your hull is melting)
Thirdly, if there is a short between live and earth on the boat, a very large current will flow through the diodes until the MCB or RCD trips. OK only a few 10s of milliseconds but enough to blow under-rated diodes. I note that they mention 120A surge current tolerance, that is very low. So if the diodes fail open circuit, it means the boat is no longer connected to earth. Potentially dangerous for humans. If the diodes fail short circuit, that means the GI is no longer protecting the boat from corrosion.
So overall it is cheap, nasty and under-specced. Possibly better than nothing, but then again if it fails and the boat is no longer earthed, it is worse than nothing. At the very least, if you do get this cheapo shite, you should check the diodes are working on a regular basis, using a volt meter and light bulb PP3 battery. Why not just fit a proper one, not a huge amount of money to protect your expensive steelwork.
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Post by Deleted on Feb 11, 2018 22:12:28 GMT
Glad accounts of your 'flounce' are exaggerated. Every beanstalk needs a giant (or village an idiot) Rog
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Post by Telemachus on Feb 11, 2018 22:30:56 GMT
Glad accounts of your 'flounce' are exaggerated. Every beanstalk needs a giant (or village an idiot) Rog Why would I flounce? It is just wishful thinking from Krissypoos. And he knows full well he'd miss me if I went! He's in luuurrrrvvvvvv! Just too shy to mention it!
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Post by Deleted on Feb 11, 2018 22:46:30 GMT
Glad accounts of your 'flounce' are exaggerated. Every beanstalk needs a giant (or village an idiot) Rog Why would I flounce? It is just wishful thinking from Krissypoos. And he knows full well he'd miss me if I went! He's in luuurrrrvvvvvv! Just too shy to mention it! I believe you did actually say you were going to stay to simply disrupt the forum. Which your posts above would seem to contradict.
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Post by Telemachus on Feb 11, 2018 23:13:52 GMT
Why would I flounce? It is just wishful thinking from Krissypoos. And he knows full well he'd miss me if I went! He's in luuurrrrvvvvvv! Just too shy to mention it! I believe you did actually say you were going to stay to simply disrupt the forum. Which your posts above would seem to contradict. Oh dear, so sue me.
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Post by Deleted on Feb 11, 2018 23:19:44 GMT
I believe you did actually say you were going to stay to simply disrupt the forum. Which your posts above would seem to contradict. Oh dear, so sue me. So you're back then to regale us with your electrical wisdom? Until somebody disagrees with you on something? I don't agree with kris very often but he sure has your measure.
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Post by Telemachus on Feb 11, 2018 23:45:54 GMT
So you're back then to regale us with your electrical wisdom? Until somebody disagrees with you on something? I don't agree with kris very often but he sure has your measure. Blimey I was only busy with other things during today, and that means I’ve flounced? Well how nice to be missed!
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Post by Deleted on Feb 12, 2018 0:24:24 GMT
So you're back then to regale us with your electrical wisdom? Until somebody disagrees with you on something? I don't agree with kris very often but he sure has your measure. Blimey I was only busy with other things during today, and that means I’ve flounced? Well how nice to be missed! I'll dig up the relevant post when I can be arsed.
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Post by kris on Feb 12, 2018 10:28:36 GMT
Glad accounts of your 'flounce' are exaggerated. Every beanstalk needs a giant (or village an idiot) Rog Why would I flounce? It is just wishful thinking from Krissypoos. And he knows full well he'd miss me if I went! He's in luuurrrrvvvvvv! Just too shy to mention it! twat.
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