Fitting electrics.

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Fitting electrics.

Postby Jim1234567 » Tue Oct 16, 2018 4:00 pm

Hi everyone,

Over the winter id like to fit electrics and a few basic instruments to my Prelude 19. From reading some of the articles on the forum I've got a bit of picture of what other people have done but would like some clarification.

Things I think I need:
Battery (12v)? if anyone has a suggestion that'd be awesome.
Isolator Switch
Switches panel
Some wire I assume? Not sure what type.
Instruments: was thinking to start with id find some cheap eBay ones such as a GPS, chart plotter maybe, nav lights, cockpit lights, cabin lights. Any suggestions on the specification/model for all these things would be great.

Also assuming most people have a solar panel/ wind generator to keep the battery topped up?

I know pretty much nothing about electrics so any general safety tips would be great as well.

Also, many threads have said they store their battery in the 'sail locker' behind the step under the cockpit but I seem to get a very small amount of that water builds up there over time.

I stupidly burnt some of the fiberglasses with a disposable bbq. It's on the cockpit floor but hasn't compromised the integrity just stained it and the top layer is crumbling a little. (The water was already forming before this happened so the two are unrelated.) Any suggestions on how to cover this up or fix it would be greatly appreciated. I was thinking maybe a really thin decking?

Many thanks
Posts: 2
Joined: Thu Oct 11, 2018 10:44 am

Re: Fitting electrics.

Postby Garyk » Wed Oct 17, 2018 3:51 pm

Hi Jim,

I'll be looking to do the same, as I should be taking ownership of a prelude very soon. I am going to pick up a relatively inexpensive integrated fuseboard/switchboard with USB connections from Ebay - search for '12V 24V 5 Gang Inline Fuse Box LED Rocker Switch Panel 2 USB Charger Socket Boat'
and you'll find a reasonable example that includes 12v socket, USBs, and fused switches.

As far as I'm aware, you need single core wire for marine applications, and yes, a 12v battery would be best. - I'm thinking of housing my battery in one of the cockpit lockers, possibly in an enclosed battery box, you could include an isolator switch but you may need to wire in an automatic bilge pump separately if you're going to include one, so you can isolate everything else but still have the bilge pump operate if needed.

I would plan led striplights with low power consumption, and also try to limit the other accessories to low power consumption models, or ones that you can charge at home to reduce the demand on the battery. I'd be interested in other peoples take on solar chargers for a small craft - I had planned to take the battery home after use, and top it up there.

Eva teak marine decking could solve your cockpit floor problem.

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Joined: Mon Apr 30, 2018 12:31 pm

Re: Fitting electrics.

Postby Barry911 » Tue Oct 23, 2018 11:09 pm

Gentlemen, one thing to consider is if you're in an inland waterway that requires you to conform to Boat Safety Scheme (BSS) requirements. These can be found on-line, or bought as hard copies.

Even if you're not, they do offer useful guidance as to best practice and after a particularly rocky start have been refined into a genuinely useful and sensible standard.

Batteries: the cheapest form of power is a standard (vehicle) lead acid 12v battery, ideally maintenance free. These automotive batteries don't like being deep discharged, many cycles of 50% discharge will damage them. This is because the plates are designed to give a hard / fast jolt of power for starting an engine. Advantage: really cheap. Actually not a terrible option if you keep them well charged. Just be aware you can only use barely half of the power stored in there.

You'll have heard of 'leisure' batteries. These are still lead acid, but have a different internal contruction making them a little more tolerant of a deep discharge. They still can't be run very flat, but you can suck more out before doing damage. The downside is they'll be quite a lot more cash than the above automotive / car battery. Beware automotive batteries dressed up as leisure. You're then paying leisure price for a lesser product. One quick guide is if there are two pairs of terminals, one clamp on type, one threaded (often with wingnuts), it's almost certainly a genuine leisure battery.

Alternative types are gel / glass mat (still an acid battery) and then you'd be into lithium types (of which I know nowt when it comes to putting these on boats).

The battery ideally wants to be mounted away from the living area, as during charging and discharging it can potentially give off hydrogen and fumes. The ideal is in a cockpit locker with a bit of ventilation. Failing that, many batteries come with a small vent pipe, and this can be piped overboard. Hydrogen gas rises of course, so it's easier to get rid of than fuel gases (propane / butane) which are heavier than air and hang about in bilges etc. Also, the battery should be mounted in some sort of tray ideally to catch any spillage and stop it from shifting about. Mine one sits in a fibreglass battery tray that is in turn is glassed to the hull. The battery is simply tied into place with cord. It's very solid and can't shift should the boat heel over.

You'll certainly want to isolate your entire electrical system, so your positive lead would come out from the battery and through an isolator switch. These are large, so you'll need heavy cable to go from the battery to the isolator, with appropriate terminals. Most of these come with a removeable red 'key' which you may choose to lock below. I just leave it in place, but switched off. Usually you find post-isolator, people drop the cable size right down.

Cables, btw: vehicle multi-strand is fine. Single core is more housing and isn't designed for situations where it could be flexed or vibrated. I have a heavy duty crimp tool, and also often use heat-sealed terminals. All of this stuff can be bought from Vehicle Wiring Products (I'm not connected with them btw). If nothing else, it's worth looking at their site for this stuff, even if you then shop around. They're pretty good actually, so are my default choice.

Anyway, the positive (red) would then come out of the isolator and head off to your fuse / switch board. These are easy to find on eBay, and can have a number of switches / outlets (eBay: boat switch panel). Some might also have a voltmeter so you can monitor the battery (lead acid batteries tell you their state of charge via voltage. Hint: if it's showing 12v or less, it's heading towards being flat. There are charts online that'll tell you).

As Gary says, one exception to the above might be a bilge pump circuit. You may choose to come off the pre-switched side of the isolator, through an in-line fuse (or an individual fuseboard) and then down to a bilge pump. This means you can throw your main isolator off when you leave the boat, but still have a bilge pump at the ready. As this is still fused, you have protected everything as best you can.

On the other side of things, the negative from the battery can go straight from the battery terminal to your fuse / switch board. There's no reason why you can't also run it round all of your electrical things in one big loop, or you can give each item (light for instance) its own negative supply. The negative supply is common to all electrical devices on the boat. It's not fused and it's not switched. If your boat was metal, we'd be calling the negative the earth, and you'd simply earth (negative) every appliance (light / pump) to a bit of the boat's metal. As we've got grp, we need to get a negative supply to anything we want to power. All switching and fusing is done on the positve / red side.

You might divide your fuse / switch board to give you cabin lights, masthead light, nav lights, bilge pump and so on. It might be that you send a supply (positive from the fuse / switch) up to, say, three cabin lights, but they can then each have their own switch as well. That way you could switch the supply on at the board, and have any combination of lights on at any time. I leave all of mine 'on' when I leave the boat, but switch off everything at the main battery isolator. When I arrive at the boat in the dark, I can grope around for the (big, easy to find) isolator in the stern locker and bingo! All cabin lights greet me.

I'm running all of the above plus I've got a Propex gas warm air heating on my current Leisure 20 (soon to be a Prelude hopefully). I visit the boat around once a month for a few days each time. I run a large leisure battery (sorry, can't remember amps) and it stays well topped up with a cheap (£15h) 5 watt solar panel. I just have it resting in the cockpit and it does a brilliant job. Just big enough to keep things topped up, not so big to need an electronic regulator. There is a ratio under which you need no battery protection, over which you'd need a regulator to prevent over-charging.

If you're going to use the boat a lot, or you're going to use a lot of power over shorter times, you might want to consider a larger solar panel with a regulator.

If you're starting from scratch, these days the only lights you'd be fitting will be LED's. These are likely to be your main current draw unless you have a car stereo (don't, they are very power-hungry). Any bilge pump will rarely run I'd imagine. Therefore you'll most likely not need much charging really. Be aware however that all lead acid derived batteries will have a degree of self-discharge even if not used. As above, if left for a long enough period they will drop below their critical discharge level and start to be damaged. Therefore, even if you only use a boat a couple of times a year, you will need to allow for 'something' to replenish the battery. That might be you taking it home now and then, solar or wind. Or, of course, you might find your outboard has a charging coil fitted. If so, this can be wired in upstream of the isolator. By this I mean, straight into the battery (you'd still fuse the positive) rather than after the isolator. This means the battery would be charged regardless of the isolator's position. This prevents a situation where you've motored for three hours thinking you've been charging up, only to realise the isolator hadn't been switched on. You'd usually have a muli-plug between the outboard and boat, so that you can quickly unplug the engine for removal.

Anyway on the positive (red) side: battery, isolator, fuse / switch board, load (lights etc)
Negative (black): battery, negative bar on fuse / switch board, and / or looped round each load point.

Bilge: own power supply, can share negative with above as negative not switched at all.

Outboard: fused between outboard and battery on positive side, negative doesn't need a fuse. Might / probably runs through a pull-out plug to allow easy outboard removal.

Think that's all I can come up with at the mo.
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Joined: Sat Oct 20, 2018 10:57 am

Re: Fitting electrics.

Postby Jim1234567 » Tue Nov 06, 2018 8:17 pm

That's brilliant thank you both so much. Looks like I'm going to have a fun winter!
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Joined: Thu Oct 11, 2018 10:44 am

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