Boat DIY??? - 12 V System installation

Discussion in 'DIY' started by cdn_spr, May 2, 2010.

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  1. Anyone have an idea on how to install a marine 12V system in a boat without one currently?

    I own a 14' runabout, which at the moment has bow and stern lights, which are haphazardly wired to alligator clips which I assume you attach to a 12V battery. However it's a mess, and I would like to replace it. I will first replace the outboard (extremely old mercury 35 hp 2-stroke) with one which contains an alternator, and I know I will need a battery, but what else, and how does it all go together? I assume a fuse box will be needed at some point? I would like to be able to have running lights, radio, fishfinder/GPS on the system.

    Any and all help is appreciated!
  2. hi

    Hows the boat clubhouse (log house) in Petawawa, I was there when we built it back in 1977

    Anyway as for boat electrics the best info is Nigel Calders books or John Payne. There is lots you can do but you will probably only need one battery for a small runabout.

    I am on Vancouver Island and both of those books are available in most library systems. I also have done lots of wiring on my boat that I live on and those books have been invaluable
  3. I got a copy of one of the sailing magazines to read on the plane on the way out last week. Can't remember which one, but it has an article in it about rewiring, things like making sure the cable you use is tinned copper wire, which connectors and fuse boxes to use.

    It was quite informative, might be worth having a troll into you local WH smiths or such like and having a flick through to find which mag it was.

    If I remember when I get back to my gaff I will PM you the title of the mag
  4. It really is not difficult electronically, as you suggest the use of fuses is one of the main things I would stress as being important. Water is your enemy here, so making sure circuits are individually isolated not only is safer but also helps when all of a sudden something just aint working so the faulty circuit can quickly be ascertained and also you will then know why the circuit has failed. Use of decent wire is also worth considering and matching it to the appliance on that circuit, no use plugging in a heater on speaker wire for instance. When I rigged up my mates boat (an old seaplane tender) I also fitted one of those big red isolator switches like they use on rally cars. That way when his boat was moored up the last thing you did was to isolate all the electrics from the battery and as such he would not be coming back to a smouldering wreck if water got in to where it shouldn't.
    There really is no limit to what you can wire in though but try where possible to wire in parrallel and keep it neat and tidy, make sure you draw yourself a circuit diagram laminate it and keep a copy near the main fuse box. Any problems you have WILL happen when it's lumpy, dark and slinging it down with rain, Mr Murphy's law ensures this!!!

    Edited due to waking up hungover lol
  5. Oh you must get one of those wind turbine thingies.I see them on lots of boats,so you should probably get one.
  6. You should be able to get a good cheap book on marine electrics from your local Chandelry, most give info on fitting a simple circuit, useing ordinary garden hose as conduit is always a good idea, to prevent water or rubbing/chaffing damage to cables, and epoxy resin is your best friend to water proof everything, but most componants, fuse boxes, switch panels ect are easily availably at all good chandelers and boat yards
  7. I’ve completely rewired a RiB dive boat and it isn’t any more difficult than a car’s electrics.

    Install conduit wherever possible, it protects the cables and makes it easier to upgrade later on (new fish finder transducer etc).

    Use Black and tan for all your ancillaries! Not only is the plastic coating pretty much bomb proof, it’s free if you know who to ask!

    Use a separate circuit for each ancillary from a bus bar and install an indicator light, switch and fuse holder on the console. It’s a lot easier to change a fuse on the console that have your head stuck under a hatch whilst a sea.

    Consider the use circuit breakers instead of fuses. They give an instant indication on what’s not working and in an emergency you can hold them in (this is a last resort measure).

    As mentioned above, definitely install a battery isolator switch (BIG RED KEY). As well as being able to isolate everything in the event of a fire, it prevents you leaving your lights on and coming back to a flat battery.

    Try and find your bits and pieces from a car parts shops rather than a chandlers, with a little silicon sealant you can make most things watertight and at a fraction of the cost.

    Plan for all your electrics and wire routing, spend the extra money on such things as bilge pumps now, it can be a bitch wiring in extra things in a years time or so.
  8. In a lot of respects you treat it like a car, but make it a bit more water proof!

    Keep the alternator/charging circuit seperate from the main electrics, if the motor is a electric start and you have space then use two batteries (one for the lights etc and one dedicated to the engine), you need to 'electrically seperate the outputs' details can be found in most good yachty electric books.

    All batteries MUST have some form of double pole isolator.
    Take the output from the battery to some form of distribution board, any decent boat chandlers will sell you one already to go, personally I would use one that protects the individual circuits with MCB's rather than fuse's... it saves trying to pick up a very small fuse with cold fingers, in the dark and the boat being bounced around in a force 8, always good for a giggle :lol:

    Use a dedicated Neutral (negative) per circuit, don't 'borrow' it makes fault finding easier and helps to prevent volt drop fek ups etc.

    You MUST size the indiviual circuits (cable) to the expected load(s), no good trying to run a high load on cable with a small CSA, it will just melt!

    Crimps, use a decent proffesional grade crimper (system with matched crimper and crimps) that has a positive release that only release's when the crimp has been subjected to the correct pressure.

    Have fun....
  9. As Vanman said a charger is also a good idea, a wind turbine might not be practicable but fitting a solar powered charger is a doddle and will keep your battery topped up
  10. He did say in the original post that he was getting a new outboard with an alternator
  11. MY boat and my campervan both have alternators,and both are fitted with solar panels, the only time I have ever been towed in by a life boet, not my boat, by the way, it was because of a flat battery
  12. It's also a good idea to include a volt meter........but only if you are willing to look at it now and again :oops:

    Not me but a group form our dive club!
  13. Have already mentioned the wiring, and agree with the bit about breakers, but to a point. They are expensive in comparison to automotive fuse blocks, although only really to be used as an alternative to CB's on low load applications. As said above a bit of silicone sealant can work wonders.
    It's not at all Heath Robinson wiring, just cost effective. No point spending all that dollar on marine specific stuff that costs such a premium if the gear is already out there.
    I suppose it's dependant on your intended usage of your vessel but honest these chandleries can charge a hefty premium as they think you have money to burn. As for seperate earthing for circuits I do not think this is necessary for low load circuits, as long as your circuit is designed well or logically there is no need not to have a common earth for ancilliaries as long as, has been said before you have indication and protection fitted on your ancils.
    Chances are that if the others are working fine and not pratting about your earth (as long as insulated all the way to the actual earth strap point at the end of the circuit) more than likely will not be the problem.
    To be totally honest if you really think you are going to have issues wiring up a 12 vdc circuit system for you usage you really should look to some help from somebody with a bit more knowledge, rather than a book. It may cost you a few beers but not much more.
    If even you follow some of the advice given on here by myself and the other posters please if not sure do not cast off until you have had it checked out for it's integrity. Only when you have piece of mind and total faith in your electrics should you do so. You cannot not have such instruments as compass lighting, nav lights, bilge pumps and other vital stuff like the beer fridge not running correctly :D :D :D
  14. Came to the conclusion that CB's were the way ahead one dark dismal night while bouncing one of BKYC's Sigma 33's past Kiel Light in a bit of a breeze (8 gusting 9) and a ‘slight swell’ running all ways... :p

    Cabin lights went pop while trying to check the ‘alleged depth’ from the chart, the box of spare fuse’s, having been opened to get the appropriate very small fuse out was last seen flying like a demented seagull across the cabin spewing the f***n fuses everywhere… :x

    It did not help that the crew (Canadians) were whining like a bunch of old wimmen having just done a quick sail change up front at the same time as the boat tried to do an impression of a diving seal... :lol:

    In my experience, Nav Lights, while pretty important do provide the drivers on those big fek orf ferries something to aim at......
  15. Thanks so much for all the replies. Felix I like the suggestion of black and tan, I am the guy to ask for it so getting a few feet of it is no problem, and will keep the cost down.

    To be honest I guess there is a reason why you do not see wiring diagrams for this sort of thing floating freely about the internet, it is a step up from DIY and I will enlist the help of some veh sparkies at work when I'm back from tour. I literally only know you need an alternator, fuse/breakers and wiring. How it all goes together is a mystery to me.

    I should have mentioned that it's for a boat who's main waterway to navigate is the Ottawa and Mattawa Rivers in Eastern Ontario, Canada, so it's strictly for inland water usage. As stated it's a 14ft open-topped runabout so I would hesitate to even put her in one of the great lakes, let alone salt-water.

    However all the advice is much appreciated!!