Rewiring small boat, have I got this right?

PaulRainbow said:
That's correct Steve.



Generally speaking, twin core is more expensive and pretty bulky when several runs are used. It's normal to use mostly single core cable for a job like this. Obviously things like the mast light should be 2 core.



There is no -VE connection to the isolator switch, you nailed it in the first paragraph above.
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Re single/twin core, I didn't see an option for single core on 12v planet, and I don't know why lamps are obviously twin core. Can you enlighten me? And tell me which items can use single core and what else would need double? Don't all my items have +ve and -ve connections? Does using single core mean just one cable is needed from , say depth log? Or does it mean two single core cables, one from the switch box and one to the bus bar?
Sorry, I need this stuff in words of one syllable.
 
steve yates said:
Re single/twin core, I didn't see an option for single core on 12v planet, and I don't know why lamps are obviously twin core. Can you enlighten me? And tell me which items can use single core and what else would need double? Don't all my items have +ve and -ve connections? Does using single core mean just one cable is needed from , say depth log? Or does it mean two single core cables, one from the switch box and one to the bus bar?
Sorry, I need this stuff in words of one syllable.
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You want twin core up the mast.

All of the stuff inside can be single core. It's cheaper and tidier to use a pair of single wires, a handful of twin core cables quickly gets bulky. Each device will need positive and negative. Also, if you have a few devices close together you can run a single negative cable to them all, making sure it's rated for the combined current draw. In fact, in an installation where there are a few devices, say wind, depth, GPS etc, that could all be powered from a single switch, it might make sense to run a pair of cable close to those instruments, to a small fuse board, then take a pair of cables from suitable individual fuses. All saves cable and is tidier.

Cable on 12v Planet https://www.12voltplanet.co.uk/single-core-tinned-copper-thin-wall-cable.html
 
Thanks all, based on what you have told me, here is my proposed circuit diagram:

wiringdiag-bethfran-1.jpg

Any issues with this?

couple of quick questions on it. Is the inline fuse ok there? or better before the isolator (the distance between isolator and battery is under 12") and based on the kit I'm wiring up, is 20a a bit on the low side? Would 30a be better?

I have read about having seperate terminal blocks wired to the switch box, seems like extra faff & space, is this necessary?

I'm thinking 1mm single core tinned for the gps/depth/compass/usb/cig lighters; 1.5mm single core for the vhf and stereo and 1.5mm twin core for the autopilot and the plotter. Would you change any of those configurations?

Last question, if I add an extra solar panel, do I add another mppt controller? or can one controller handle 2 different solar panels?
 
steve yates said:
Thanks all, based on what you have told me, here is my proposed circuit diagram:

View attachment 79021

Any issues with this?

couple of quick questions on it. Is the inline fuse ok there? or better before the isolator (the distance between isolator and battery is under 12") and based on the kit I'm wiring up, is 20a a bit on the low side? Would 30a be better?
Click to expand...

Looks OK in general. The fuse should be close to the battery, it then protects all of the cable and the switch. If you are using 16mm cable, fit a 100a midi fuse. It might seem over the top for you equipment, but it'll never blow unless there is a short in the cable, the cable is rated at 110a and the fuse is only there to protect that cable and the switch.

Also, fit a fuse close to the battery for the solar controller, again, rate it for the cable.

I have read about having seperate terminal blocks wired to the switch box, seems like extra faff & space, is this necessary?
Click to expand...

Not usually, depends on the switch panel.

I'm thinking 1mm single core tinned for the gps/depth/compass/usb/cig lighters; 1.5mm single core for the vhf and stereo and 1.5mm twin core for the autopilot and the plotter. Would you change any of those configurations?
Click to expand...

Sensible choice with the twin core. Nothing wrong with using 1mm and 1.5mm, but, it might well work out cheaper to buy a full roll of red and black 1.5mm, especially as you plan to do some work on the Longbow. I generally use 1.5mm for everything up the that rating, then go up to 2.5mm for stuff that 1.5mm isn't man enough for.

Last question, if I add an extra solar panel, do I add another mppt controller? or can one controller handle 2 different solar panels?
Click to expand...

If the controller and the wiring to the battery is rated for the combined output of the two panels, wire them in parallel to the one controller.
 
ghostlymoron said:
Thats outrageous
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It is isn't it! Not sure what I was looking at, but your comment made me look again quickly, and saw charging coils on ebay for £20! So messaged a local marine engine mechanic and he said charging could be added to the outboard for £130 if the flywheel didn't need changing, £230 if it did. That puts a whole new complexion on it! So thank you for bringing it up on the thread and making me revisit it.

I wont do it now, no budget for it, but it will go on her treat list for the future, along with new sails :)
 
steve yates said:
It is isn't it! Not sure what I was looking at, but your comment made me look again quickly, and saw charging coils on ebay for £20! So messaged a local marine engine mechanic and he said charging could be added to the outboard for £130 if the flywheel didn't need changing, £230 if it did. That puts a whole new complexion on it! So thank you for bringing it up on the thread and making me revisit it.

I wont do it now, no budget for it, but it will go on her treat list for the future, along with new sails :)
Click to expand...

The charging you get from a charging coil and rectifier on an outboard engine is usually pretty pathetic.

Usually very few amps unless the engine is running at a moderate RPM or more, even then not many and very few Ah unless you are running the engine for a good few hours. Ideally you only run the engine for a short while and at little more than a fast idle to get on or off the mooring / in or out of the marina etc.

My outboard, being the sail version, came with battery charging as standard but I still had to take the battery home periodically for recharging until I invested in a small solar panel

My advice would be not to waste money on retro-fitting a charging kit but to invest in more solar panels
 
Fair points, and I'll see how I get on in real life operating with solar panels. But I do quite long trips in the wee boat when she is in use, and I've often puttered along under outboard for 10 hour crossings on calm days, so for a hundred odd quid, and with limited deck space for panels, it's still something that might be worth doing for me. And if it saves a night in a marina & a pub cos I have enough power to anchor somewhere quiet, it would soon pay for itself :)
 
The current should go from the battery +ve, through the main fuse, in one end of the isolator switch, out the other end, through the relevant circuit breaker/fuse in the switch panel to the +ve terminal on the piece of equipment, then from its -ve terminal to the -ve bus bar in the switch panel and thence back to the -ve side of the battery.
 
If you are planning to use LEDs for the cabin, which gives a worthwhile saving in power, note that They only work one way round. if the bulb doesnt work when you first switch on, simply reverse the connecting wires. If they have two contacts on the bottom lf the bulb, (unusual!) simply put it in the other way round to get the polarity right.
 
LadyInBed said:
I thought about it but decided that as each load circuit was fused it would be unnecessary, but it would be a different story if there was an alternator involved.
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The wiring from the battery and isolator to the panel panel should be protected by a fuse , in the same way as the wiring between the battery and solar system is protected unless maybe the wiring is short and run in such a way that no short circuit is possible.
The load fuses protect the load circuits.

I don't see what difference an alternator would make.
 
My Honda BF6 has a quoted output of 5amps which is not negligible even if you get half that at cruising speed. I like the idea of having an alternative source of charge to solar. I don't know if DIY modification is feasible but that would make it quite affordable.
VicS said:
The charging you get from a charging coil and rectifier on an outboard engine is usually pretty pathetic.

Usually very few amps unless the engine is running at a moderate RPM or more, even then not many and very few Ah unless you are running the engine for a good few hours. Ideally you only run the engine for a short while and at little more than a fast idle to get on or off the mooring / in or out of the marina etc.

My outboard, being the sail version, came with battery charging as standard but I still had to take the battery home periodically for recharging until I invested in a small solar panel

My advice would be not to waste money on retro-fitting a charging kit but to invest in more solar panels
Click to expand...
 
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