Getting on with boat re-build

[purple5ive]

I run large draw accessories such as deckwash and huge bilge pump from relays mounted right next to battery in back corner of boat and switch up front to turn on relays when needed so no need for big cable going to front of boat and then back again can post pics tomorrow in daylight if u need clarification

if im not mistaken this is what ducky suggested but this is an improved version where no bigger cables are running to helm and back because the relays are not at the helm but at the back where the batteries usually are, and which is where the deck wash will be as well..

[Gultch78]

I run large draw accessories such as deckwash and huge bilge pump from relays mounted right next to battery in back corner of boat and switch up front to turn on relays when needed so no need for big cable going to front of boat and then back again can post pics tomorrow in daylight if u need clarification

if im not mistaken this is what ducky suggested but this is an improved version where no bigger cables are running to helm and back because the relays are not at the helm but at the back where the batteries usually are, and which is where the deck wash will be as well..

Yes same as ducky has suggested with a twist

[SteveoTheTiger]

(Steveo, I shall add a bit of a basics to this reply, hope it helps)

heavier gauge wire than is required for the longer length required, especially up and back to/from the helm. For those that may not know, the longer a wire travels, the more resistance the wire has for the current (Amps) to travel through, which drops the voltage at the end AND heats up the wire, even melting it if it gets too hot.

Cheers, Bugzzzz

Thanks Bug.

I get the basics, such as how a circuit works etc. Its the details like what gauge wire to use and things like that. Like most things, i suspect it is just a matter of jumping in and having a go.

Its a bit like the trailer bearings. I have no doubt i could do it myself.. i just dont know how to. And i am weary of having a go incase i do it wrong.

Dangar Stu is a big help.

[ducky]

Yes suggestions make sense provided you can get them waterproof or close to.

In my head I’m thinking of my centre console build which will have battery’s in the console. Not up the back. 20A cable isn’t too heavy duty though.

[ducky]

Don’t forget to fuse it too. If you are throwing it up the back with the relay direct off the battery.

[Bugatti]

Yes suggestions make sense provided you can get them waterproof or close to.

In my head I’m thinking of my centre console build which will have battery’s in the console. Not up the back. 20A cable isn’t too heavy duty though.

That's right ducky, 20A (or slightly higher for the length required) isn't heavy duty as one might think like "Battery Cables" are. And you have to run wires (be it lighter gauge) to the stern to actuate the relay anyway, so for a little extra, you can run slightly heavier gauge wires to the front instead.

As you said, if the battery is in the centre console, you save on bringing primary load cables from a stern placed battery, but you still need to run load wires to the stern for the deck wash from the centre console. So for the minimal extra outlay of running 20A or slightly heavier gauge wires, in-lieu of lighter gauge relay switching wires to a stern located relay.

In other words, the same amount of wires need to run to the same specific locations, battery - console - relay - deck-wash , , , , it's only a matter of what different gauge you need or are "saving" on (coupla bucks) , for running those wires to different proposed locations of the relay and/or the deck-wash.

And as blacklab has a well organised wired helm, seems best to keep all the circuitry, components there (neater, dryer, easier access) and only run wires "to" devices/equipment to power them up, rather than "off helm" switching circuitry to power those devices up.

Cheers, Bugs


ps. When I re-wired my boat, I ran a pair of heavy gauge cables to a heavy-duty bus-bar to/at the helm, to alleviate having to run multiple cables every time. This way, with wiring additions, I access "power" from the helm bus-bar and not from the battery AND definitely not "piggy-back" off a lighter gauged OR a lighter/amped other circuit. Each addition, runs independently from an adequate Helm Power Source.

[blacklab99]

Well explained Bugs,
Yes, two options, position the relay down back, which would mean the existing switch at the helm can be used, run a smaller cable down back to the activate the relay, then have a shorter thicker cable, with water proof fuse, direct to the wash pump.
OR, have the relay up front, and run a thicker cable down back direct to the wash down pump, but still being able to use the existing 15 amp switch.
I haven't decided as yet which way to go, I don't mind having to run thicker cable from the helm, to the back corner, I think that way my wire cluster is kep't at the helm, don't need a water proof fuse and keeps the back cleaner of wire clusters.
I will have to do a tally up, of what power I already have running up from the back to the Pos. Buzz bar I have at the helm. it's a 150 amp Buzz bar, so should handle all of my electrical needs. It's surprising how all the loads add up... I am keeping a tab on it.
Stevo, I've gone into this, with an absolute hate for anything electrical, but, so far haven't had to worry about wire ratings yet as it's all been close quarter stuff at the helm, with the furtherest I've had to run is about 2 meters, I've used 22 amp rated wire so far, with the highest amp device only drawing 10 amps,some only drawing a few amps, I decided to keep it all the same gauge, overkill for some items yes, but it's kept it uniformed. Running wires, 6 meters down back, is just a case of up sizing the wire thickness to compensate for voltage loss over that distance, going bigger, it's only adding a relatively little cost in the scheme of things, so I prefer doing that to be safe and sure.
I do want every switch at the helm, I can see the sense of having it down the back, where the deck wash is, but I prefer control at the helm.
The hardest thing so far with this re wire, has been crimping and soldering, that took me a fair bit of practice to get right, the second hardest thing, is routing the wires, making it neat and functional and easily got too for any repairs, that's taken the most brain wattage to get my head around...

Col

[ducky]

Couple of things. I know it’s not AC but the theory remains the same.

You can wire a house with 150A worth of loads on a let’s say 63A supply legally provided your main switch is a corcuit breaker sized to protect the incoming mains. Ie a 63A circuit breaker. It’s called max demand by limitation.

Also when calculating max demand for the sizing of mains you don’t assume everything is running at once. For a house/commercial premises there’s charts you can follow to determine what the likely max demand is.

Obviously your boat won’t follow a chart. But you can make your own to determine what you are likely to be drawing. I’d be very surprised if you went anywhere near the limits of your bus.

Let’s say the deck wash draws 18A and the bilge draws 10A. It’s not a far reach to expect these to be on at the same time. But highly unlikely they are going to be both on at the same time that you are operating your anchor winch for example. Just protect your supply using a rated circuit breaker just below the max for the cable and obviously sized appropriately for what you’re drawing and everything will be sweet.

On a similar note. You aren’t going to get ridiculously large voltage drop over a 6m cable run. That’s still a very short cable run even though the voltage drop over distance on DC can be quite substantial. Dont oversize your cables too much...

[blacklab99]

Thanks Ducky,
Yeah, I figured that there wasn't really a time that everything was going to be on at the same time. I probably didn't need my Pos. buzz bar to have such a large amp capability, it wasn't that much more in going up to that larger one.
My anchor winch is on a separate fused switch direct to the battery, so that's out of the way.
The only reason I kept the wiring the same up front was purely for the ease of having the same connectors connecting to the switch panels, I know some blokes change wire size for every electrical item to suit, I just kept it all at the 4mm auto tinned ( 14 awg from memory).
For cable running down the back, I'll get conformation from the supplier, he said he would do the maths for me when I give him the lengths I need.
It's been a big learning curve doing this, and in all honesty, I would have been absolutely dead in the water pryor to this, if I ever had an electrical issue out wide, so in that respect, it's definitely been a great learning curve....

Col

[russellh2]

Hi Col - Good to see you are progressing with re-build - As we have discussed before - The wiring can be quite a challenge - I see that you seem to be getting on top of it - Do not forget to create a schematic of ALL of the wiring - Identify every separate circuit with a number on it, where it starts and where it goes to as well as the Insulation colour. Keep a copy in a waterproof container on boat at all times as well as spare fuses - Never know when you might need them - Keep a copy on your computer as well.