boat wiring

[scottar]

The 2 B&S will only be required for starting. 6mm twin will be fine for the main supply unless you have a high current demand (30 amps plus)

[scottar]

Better practice to run all conductors from the same circuit back to the same location so your light and bait tank pump negatives should go back to the negative bus at the front of the boat.
I would also have a switch for the bilge pump & relocate it's wiring to the front of the boat.
Cable sizes, learn to talk, work & think in Metric cross sectional area, 2mm & 8mm have no meaning without further description.
An alternative to your wiring could be a fused positive plus a negative run from the battery to the front, a positive & negative link at the front, 3 switches for pumps & lights (leaving space for any extras) on the dash and use the built in switches and inline fuses that come with your electronics. Like mine it's only a small boat & there's no need to over complicate it.

"mm" is actually a gauge of cable so it does have meaning.

https://jaydeeautocables.com.au/pages/cable-size-chart

mm2 is not mm though.

[Fed]

https://jaydeeautocables.com.au/pages/cable-size-chart

Exactly the point I was making Scottar.
The 2 mm and 8 mm in the original circuit diagram aren't even listed in the chart.
I have doubt about the values listed in the circuit diagram.
Trust an auto electrician (is that a job?) to change the Pi R squared mantra into Pi D squared divided by 4.

[Tony_N]

Thanks for the further info scottar and Fed - It came to my email - but I don't see it on the Ausfish site (??)

I have modified my plan (see attached) - I'd appreciate it if you would give me the nod if I've got it right now. No idea me! Also my 60 amp circuit breakers are now looking to be a bit overkill - should I replace them with lower amp one's ?


Cheers - Tony

Attachment 119938

[scottar]

Attachment didn't work Tony. The breakers not only have to be large enough to handle the expected current, they also have to be small enough to trip before a short circuit or over current situation, should one occur, turns all your hard work into an impromptu barbeque - not a good look. As an example for 6mm twin I would normally be fitting a 30 amp fuse or breaker.

[Tony_N]

G'day

scottar has recommended that I reduce the size of my cable after the starting circuit. I have had a go at that and there should be an image beow, Both batteries will be availabe for starting either singly or together. He also suggested that the 60 amp circuit breakers were far too big. I was wondering if maybe the fuses in the switch box would protect the smaller cables and the big circuit breakers might protect the engine? - or should I chuck the 50 amp ones and buy 30 amp circuit breakers for up close to the *ve battery terminals?

I can't afford to pay someone to do this and I don't know any sparkies - I'm a bit out of my depth (bleeding obvioiusly) - so any productive advice would be gratefully received

Cheers - Tony

[blairv70]

Only thing I would add is maybe hook the bilge pump directly to the battery so it still works without the battery isolater on incase you are moored. I actually run 2 x Bilge pumps for safety and keep one fully automatic but with a manual override via a push button on the dash - also allows for testing.

Also be aware of your bait tank pump - they can drw some power if the get a blockage.

I find the BlueSea 12 way fuse boxes to be the best - https://www.bluesea.com/products/502..._Bus_and_Cover

[blacklab]

Good advice blairv on the bilge pump set up, i'm doing the same.
As mentioned before Tony, I'm near ready to start thinking about wiring and I am a complete novice when it comes to anything electrickery.
I'm using all BlueSea products, I'm buying from a bloke in Perth who is an agent for BlueSeas and an auto Electrician himself, He sells on Fleabay under the name "Madfisher". Now he has been brilliant, even makes himself available via Phone to pick his brains and get advice. In fact, he initiated a call to me after I purchased some of his switch panels. It's his business on the side, which I think he is setting it up for his retirement.
Anyhow, I'm handy with all things, but a numb skull as far as wiring, but he has helped me with general components, but has made himself available for when I'm ready for wire size and best practice, obviously with the objective of me buying thru him, which I'm more than happy because of the advice being received.
When you work with wiring, ie obviously Scott does, it becomes second nature, but when you don't, it does becomes a very daunting task getting your head around even the basics....... I'd luv to throw the coin at a local outfit just to come and do mine, but the quotes I got, made that option out of the question, with still a soft top, new fuel tank and a new 4 stroke left to get, you tend to " do what you can". Luckily I have an auto electrician across the road from my factory, so I will pay the bloke a couple of hours to come in and go over my work once it's done.
I'f you want this suppliers contact details Tony, P.M me and I'll pass it on........HTH

Col

[Tony_N]

heya again Col

Nice post fella - sounds like you have found a good support system for your journey into the unknown. I'm now well into retirement so have the time to stumble through the miasma.. Ausfish provides a lifeline for me - let us all know when you get your barque in the water

cheers

Tony

[scottar]

Circuit breakers typically aren't used in the supply lines to the main battery switch - I was thinking that was for the main accessory supply. You can fit them if you wish but they should be spec'd at the correct size for your starting requirements (if you are electric start) and your start cable size. Typically you will be talking 150 - 200 amp breakers.

[scottar]

A very basic set up.
Basic wiring.pdf

You can add a permanent bilge pump feed if you wish - personally I don't have one. Even my stereo memory goes dead when the batteries are turned off. If I want to leave my boat at anchor, the battery for house simply stays on. If you do remember to fuse it appropriately. The twelve circuit fuse blocks are available in two different versions. Some have the negative bus built in, some don't. Getting the one with the built in negative makes it a simple neat and tidy install. Neat installation is all about cable management - get some proper screw on cable tie mounts - not the single use screw on ties. If you don't have anything to screw to, resin coat some ply and sika it in place as required. If you want to install a heavy negative busbar down the back instead of having multiple terminals on the negative post, they are available but they need to be rated for your starting current. On a basic set up though it will make little difference - even less if you source batteries that have posts and terminals as you can connect to both and not have so many wires on one.

[Tony_N]

OK - thanks scottar - so people talk about fuses within 7 inches of the batteries... are they talking 150-200 amp fuses for that ?? - do you think I'll trip the breakers every time we do an electric start ? the awg 2 cable to the batteries is about 170 amps from memory - but I understood that the high amperage of the wire was to prevent amp loss over distance?? This stuff really is secret men's business - somebody should write a simple book for dummies. I'd be the prime target for that book.

[scottar]

Most boats simply don't have fuses in the start cables period. The fuses everyone is refering to are the ones for lighter cables like the sub main or accesories direct wired to the battery

[blacklab]

Tony, How have you gone with everything ?????
Mine starts in the next couple of weeks, so keen to know how you went...

Col