do i need one!!!!

[Amulet]

Interesting reading, however, would I be safe using one of these View attachment 37012 from shore power to the boat?

If you use it for running mains appliances which have no connection to the boat's DC (normally 12 volt) system you have no galvanic problems. If you use it in any way that connects the earth from the mains supply to the earth (-ve) of the boat's system then you should in principle have a galvanic isolator in the earth lead for the reasons explained succinctly by VicS and confusingly by me. My battery charger, for example, causes such an link between the boat and mains earth. I, sloppily, wouldn't bother if it was just for sporadic use - however my battery charger is connected all the time when I'm not on the boat.

 

[sailinglegend420]

And when the marina supply is reversed you electrocute yourself.

If you get it wrong you may not kill yourself but anyone swimming or falling in the water around your boat. There are many examples of this - see Nigel Calder.

AC on board a boat can be lethal which is why Sailorman is correct when he says get a Pro to install it. If you have to ask questions about Galvanic Isolators then your knowledge is lacking. If you can't understand explanations you have read how can you understand other texts that you will have to read before installing AC on board.

If you do install AC then you should install a battery charger, or have solar, to keep the batteries up to 100%. This is another complicated area, and a cheap Halfords car charger, or similar, should never be installed on a boat.

 

[VicS]

. My battery charger, for example, causes such an link between the boat and mains earth. I, sloppily, wouldn't bother if it was just for sporadic use - however my battery charger is connected all the time when I'm not on the boat.

Something to be very aware of.
My portable (automatic, multistage ) charger has no connection between its output and earth. In fact it has an all plastic case and only a two wire mains connection. Even a couple of old ( very old) basic chargers with earthed metal cases have isolated outputs.

Presumably some reason why chargers intended for fixed marine use have a non isolated output ????

If you get it wrong you may not kill yourself but anyone swimming or falling in the water around your boat. There are many examples of this - see Nigel Calder.

AC on board a boat can be lethal which is why Sailorman is correct when he says get a Pro to install it. If you have to ask questions about Galvanic Isolators then your knowledge is lacking. If you can't understand explanations you have read how can you understand other texts that you will have to read before installing AC on board.

If you do install AC then you should install a battery charger, or have solar, to keep the batteries up to 100%. This is another complicated area, and a cheap Halfords car charger, or similar, should never be installed on a boat.

Swimmers are most at risk in fresh water I believe.


What is needed to maintain batteries at 100% is an automatic multistage charger. Not to be confused with basic chargers, Halfords or otherwise. Halfords do sell automatic multistage chargers, both their own brand and others although maybe not intended or suitable for permanent installation on a boat. Mine was bought, on a whim, from Halfords, although not their own brand nor for use on the boat .... no shorepower out at my mooring !

 

[bikerbill]

If you use it for running mains appliances which have no connection to the boat's DC (normally 12 volt) system you have no galvanic problems. If you use it in any way that connects the earth from the mains supply to the earth (-ve) of the boat's system then you should in principle have a galvanic isolator in the earth lead for the reasons explained succinctly by VicS and confusingly by me. My battery charger, for example, causes such an link between the boat and mains earth. I, sloppily, wouldn't bother if it was just for sporadic use - however my battery charger is connected all the time when I'm not on the boat.

Thanks Amulet, am I right in thinking that if I disconnect the DC wiring that supplies the lights & NASA instruments from the battery (easy to do), before I connect a battery charger from the mains, it should be safe enough?