Earthed plate boat question.

[outwide1]

As some of you are aware I have just completed the build of the new Outwide 8m Performance Plate boat.
I have a question regarding a earth issue.
I think it wasn't until the engines were fitted that I now can place my test light on the plate of the boat and have a earth.
Is this right?
If not I can't think how it has happened.
The only thing I could think it would be is a wire touching that has rubbed through.
I have run the earths to buzz bars up front from the batteries and to and from the isolation switches.
Some advise would be great as I am a little concerned.
Mick.

[Back In Black]

Get a cat

[Gr0wler]

The engines will earth the hull Mick, and you want it earthed IMO.

[Gr0wler]

Oh and it's nice to see a neat wiring job.

[Nick H]

Hi Mick, the engine is grounded to the hull even if they have a earth back to the battery (pretty sure it would be near impossible to do so with an outboard) if any of your other wiring is earthed to the hull then I believe it becomes an issue due to different voltages being earthed to the same point. Voltage out put on your VHF is different to the engine etc. that's my understanding of it but I'm no marine electrician. One question I have is how did you check to see if the circuit was earthed to the hull?
Cheers Nick

[Moejoes]

Hi Mick,
Great looking wiring......
Quick question, is that the only positive wire you have feeding your fuse boxes?
If so, it looks a little under rated for the amperage you'll draw through it when everything is on.
Could be a fire hazard!!!!!
Yes, your motors are also probably earthed to the hull & batteries.
Pretty sure mine are.
You could always change the name of your boat to "Aspirin" as you could watch it dissolve it the water LOL.
Earthing should be ok if all run back to bus bars.

[lembo]

positive and negative, red and black.
no where in your boat should any electronics have a negative attatching to the hull, eg all electronics should have a negative bar and positive bar, and both those bars will go straight back to the battery positive and negative and will not be attatched to your hull in any way. but once your motors went on the 2 big starter wires going to your motor, the positive goes to a lug on your starter motor the negative goes to a bolt that is just the block of your motor once that negative went onto your block because the motor is bolted to the ally hull the whole hull is also at the same negative potential now.
where before motors went on the hull was fully isolated from the negative.
its not a problem but do not use your hull as a negative for any of your electronics, its a poor negative because of paint and because it goes through your motor, and it will cause a large amount of electrolysis in your hull. all electronic positive and negatives need to run to your battery (buzz bar) through insulated wire.
hope this helps. nothing wrong with your boat its all good and great job on wiring.

[frank100]

Great job, 100% on what Lembo said, BUT it's called a BUS bar. Hopefully the red wires come from the battery isolator, as Moejoes says the wire looks a bit small. But I suspect the fuse panel on the right has another red wire either from the "Stud" on the left or from another battery (some people like to separate gear onto different batteries ) for example I supply my motor and winch from one battery and all other gear from the other battery.
Frank

[outwide1]

Ok,Firstly at no stage have i used the boat to earth anything at all.Every thing is off buzz bars.
I ran battery size cable to the front from the house battery via the VSR unit
I just checked the wire that is a concern and it is 6-8mm.
They have run that to the first fuse box and then a separate wire the same diameter to the next fuse box off the post of the first fuse box.
Those fuse boxes only power low drawing lights and 2 bilge pumps.
All the sounders,radar,AIS,and fridge run off there own power source.
If it is a concern its a easy fix.
What size would you suggest?
As I said though it is only looking after low draw lights.

[lembo]

I didn't mean to imply you hooked up negatives to hull. I was just saying ive seen it done and its a big no no. I looked at buying a 6500 sailfish cat that was surprisingly cheap. and he had all negatives connected to big plate welded straight to hull. and man I was screwed, some of the ally wouldn't of been 1mm thick, had patches cut out and re welded. boat was dissolving like asprin.

[Moejoes]

Mick,
Not having a go at you. At first glance there appeared to be one wire running to the whole system which looked a little small in diameter, hence the question.
I now see there is a secondary one running back around. Looks great.
I'm no electrician by trade and I did do all my own wiring on Moejoes, I searched the net for information in the process to ensure wiring was adequate.
Eg: correct diameter for length run, voltage drop & expected amperage being drawn through them.
Table attached which might help.
Say you want to run 1 meter of cabling ( Including negative, so 0.5 meter Pos. & Neg. )
Acceptable cable diameter would then be 4.6mm2 which you could run a max. of 25 to 30amps through.
That's how I read it, Sparkies feel free to correct me if I'm wrong......
Last thing anyone would want is an electrical fault offshore.
Something I am paranoid about, that is why everything on Moejoes was wired independently & could be easily isolated.
I've got your back Mick

[outwide1]

Cheers for all your input guys,Sorry if I sounded like I was pissed.
Not the case at all,its why we post so we can get information.
Its funny when you read back on your replies and they could be taken out of prospective.
I went out to the boat straight away and checked.
I am so paranoid with this bloody boat.

I had Wayne(KITTYKAT) Perform the terminating,I simply ran the 300m plus of wire.
He use to do it for a living and I had faith in his work.

[Moejoes]

All good Mick,
I'm sure Wayne's all over it.
Sorry, we appear to have diverted from your original concern, earthing

[outwide1]

I went out to the garden ornament tonight and the earth seems to be more down towards the rear of the boat.
I am also chasing some advise on Anchors,I have always run the mooloolaba picks.I'm guessing it's between the sarca or manson.
Whats your thoughts?

[frank100]

All good mate, like I said great job, you only have to worry if their are any negatives joined to the boat other than the motor (s). From what you have said that's not an issue, also the wire size not an issue since the right side fuse panel has a feed from the "stud".
Would'nt mind a pic or two of your layout from the front ie sounders, eng instruments etc. I am looking for ideas.
sarca gets my vote, even though I have lost one (bugger !).
Frank