Rewiring sailboat

Discussion in 'Electrical Systems' started by dwayne, Dec 29, 2005.

  1. dwayne
    Joined: Dec 2005
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    Location: Bradford, Canada

    dwayne New Member

    Hello everyone, this is my first post. I have a question about rewiring my boat, from stem to stern, to top of mast. Before I ask I will introduce myself:

    I live in Canada (Ontario) and last June (2005) I purchased my very first boat, not only a boat but a sailboat, which I will someday learn to actually sail. The boat is a 1973 Northern 25. Before purchasing the boat, I had it surveyed, and there were some issues, mainly the bulkheads being rotted, which I am replacing with grade 3003 Aluminum sheet, and the wiring system was rather outdated, i.e. no GFI outlets that sort of thing and some cosmetic issues which I am dealing with in the Spring. I have also passed the Boating Course with Canadian Power and Sail, so I do have a basic idea of boating, navigation, buoyage system, and boat systems.

    I have ordered the book from Don Casey, Sailboat Electrical Systems but it wont arrive for a few more days, and I am hoping the book will cover in detail the questions I am about to ask. Perhaps if someone has this book they could advise if the questions I am asking are covered in detail.

    First, I know I need a battery charger to run off the AC circuit to charge house and starting battery, and a battery selector switch, and a power distribution panel to cover the basics as I understand them. What I don't know is actually connecting all this stuff together, as well as wiring a 30W solar array, which I would LIKE to install but not necessary at this point. My other major, obstacle is the cost of the power panels. The ones that I think will serve my purpose are all at least $300 US, that really cuts into my budget but if that's what they cost...then I bite the bullet. I'm also going to replace all the Nav lights with LED's, to cut back on the load to the battery, as well as wiring in a small stereo, and a new VHF; the VHF is getting priority. I have an idea, and common sense approach to how to do this, but not sure if my there is a better way to do this.

    Thanks in advance

  2. bilgeboy
    Joined: Dec 2005
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    bilgeboy Senior Member

    Hi Dwayne,

    Just a little observation, I've made the same mistake quite a few times, even recently here.

    Your first question sounds like "Help me rewire my entire boat."
    A mighty big task! You get better responses with particular questions. In short, you are probably going to have to read the book first, and get help here. Nigel Calder has a good book too, and a writing style that appeals to me. Home wiring is easy, boats get much more complicated, lots to learn.

    The problem with the scenario is that you will be an expert boat electrician only after the job is done. Ironic, but that is how she goes.

    What a great project, best of luck.

  3. gonzo
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    gonzo Senior Member

    Navigation lights have to conform to certain standards for intensity and color. Are you sure the LEDs are compliant?
  4. Vince Hosea
    Joined: Dec 2005
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    Vince Hosea Junior Member

    Casey's book is a good starting place, I would also highly recommend Charlie Wing's Boatowner's Illustrated Handbook of Wiring and Nigel Calder's Boatowner's Mechanical and Electrical Manual. Also, get a West Marine catalog, the electrical component descriptions in the electrical section are informative.
    Don't even think about reaching for the tools. The very first thing you need to do is draw a skematic of your current system. This drawing needs to include the guage of the wires, the length of the wiring runs, the amount of amps the various components draw and the ability of your power suppy. Designing an electrical system is all about the numbers, and following the formulas of load calculation and usage. These systems only work properly when you follow the rules. For your boat, you don't have to be an engineer to do this, just educate yourself. If this is something that you're not inclined towards, then I would recommend showing your designs to an electrical engineer or a marine electrician with years of experience. If anything you will have started to build a manual for your boat, which is seemingly rare. That alone will save time and money for repair issues. Also, these kind of jobs make you really good at what you do. The above mentioned books tell you how to make these computations and design a functional system. I can't emphasize how important the design process is - that is where it starts. This should make this task less overwhelming and more organized.
  5. ABoatGuy
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    ABoatGuy Member

    And get a copy of E-11 from ABYC
  6. Theodora
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    Theodora Junior Member

    Go to and download their book "Energy Unlimited". It will giev you a good grounding in the equipment available and what it does.
  7. luckettg
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    luckettg Junior Member

  8. Ike
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    Ike Senior Member

    What Vince said. I echo that. Here is a list of the best books on boat electrical systems.
    Boating Magazine's Powerboater's Guide to Electrical Systems by Ed Sherman
    Boatowner's Illustrated Handbook of Wiring, by Charlie Wing
    Your Boat's Electrical System, by Conrad Miller and E. S. Maloney
    Boatowner's Mechanical and Electrical Manual, by Nigel Calder
    The 12 Volt Bible, by Miner K Brotherton and Ed Sherman

    Also as was said get a copy from ABYC of E-11. Http://

    Here is the page for Canada's Office of Boating Safety electrical standards for boats.

    There are some very informative links on my web site, scroll down to Electrical Systems on the right

    You might want to look at the electrical page too.

    When you have both a 12V DC and a 120 Volt AC on your boat you have two separate systems that a connected at only one point, the common ground. Each system needs to be designed separately. Start with the DC system. Decide what equipment you want to have and where it is going to go. Make a simple diagram of the wiring for these. Then figure out the length of wire to each item from the breaker or fuse panel. calculate your loads so you can size the wire. Figure out the size of each breaker or fuse. Then draw a diagram of the actual layout on the boat so you can figure where to put the wires. Remember when calculating lengths that the wires will not go in a straight line and they need to be fastened down every 18 inches or so.

    By the way, don't scrimp on the electrical panels. Cheap panels can end up being a real problem.

    Make sure you ask questions here if you need more information
  9. gonzo
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    gonzo Senior Member

    Are you sure aluminum bulkheads are proper? A harder or stronger material is often worse because it produces localized loads that will cause structural failure.
  10. luckettg
    Joined: Mar 2005
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    luckettg Junior Member

    I wonder what the old bulkhead material was? Using aluminum may cause other problems to, such as galvanic corrosion.
    Greg Luckett

    Joined: Dec 2006
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    Location: Napier NewZealand


    Rewiring sail boat


    My name is david

    I iam involved in marine electronics as a profession I can only give you two bits of advice at this point firstly as you are connecting your vessel to ac power ie shore power get yourself an isolating transformer dont rely on the battery charger as beiging your isolating transformer

    And secondly purchase this book marine diesel and electrical maintenaince

    By Nigel Calder He would be the the utmost authority in the field of marine electronics this book in New Zealand is often refered to as the sailors BIBLE
    One other tip bonding is imperative i cannot stress this enougth

    But the book will explain all and its in laymans terms

    If you want to conntact me i work for vectek electronics napier new zealand

    my email is

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