First boat project and first time boat owner all in one [long post]

Discussion in 'OnBoard Electronics & Controls' started by tommygfunk, Aug 18, 2009.

  1. tommygfunk
    Joined: Aug 2009
    Posts: 1
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Ojio

    tommygfunk New Member

    I just bought a 1976 glastex seastar 16’ try haul and well it needs TLC [tender love and cash} she seams solid, but I haven’t really torn into her. My problem at this time is that critters have made away with chunks of the wiring and being the third owner of the old girl the wiring is hacked together out of many bits. She has a 1976 evinrude 2 cylinder two stroke outboard motor on it and just the basic electoral stuff like the Bilge pump, lights, and the battery cables [one white one black]

    On the dash is a toggle switch that locks to the left and is an intermittent switch to the right with a indicator light, a push button that I’m assume is a start button. The ignition and a toggle are on the controls. There is a push pull switch that is the lights on the dash too. The wiring that is left is not worth saving and it seams that the ignition wires are safely in a sleeve that heads directly to the motor.

    Here are a few questions floating around.
    1 Does the power come directly off the battery?
    2 Is it possible to put in a small fuse box so later I can put in a radio and fish finder so I don’t have a bunch of + & - wires running everywhere?

    I have not heard the motor run yet and it has sat for two tears. It was properly winterized, but you never know. That is a post for another section.

    Tom
     
  2. Tim B
    Joined: Jan 2003
    Posts: 1,438
    Likes: 59, Points: 0, Legacy Rep: 841
    Location: Southern England

    Tim B Senior Member

    Tom,

    Apologies in advance if anything in this post is REALLY obvious to you, but I'm just trying to detail all the steps.

    You are in the convenient (and rare) position of being able to re-wire the whole boat to suit YOUR needs and the current best practices. I would start by writing down a list of all the stuff you will need. This will include:

    Battery
    Bilge Pump
    Lights (Panel+Nav)
    Switch Panel (may not be big, but should include voltmeter and ammeter)
    Engine

    Draw "pinout" (ie. which wire/connection does what) diagrams (if not supplied) of all the kit that you currently have (including the engine). This will tell you what needs to connect to the battery, ignition switch etc.

    Once you have this, consider what else you want to add, Radios, GPS/Nav etc. and do the same as above.

    With a boat this size, you only really need to worry about the total current load, not a load schedule (which makes life a bit easier). Write down the current each device takes (Batteries count as 0 and engines are 0 or negative (depends if you know the max alternator output)). Hopefully you get a number which is less than 0. This means that you have an excess of supplied power from the engine (remember that the battery is just a store). A positive figure means that you're drawing more power than you're supplying, so you will need to find an additional power source.

    Because this is a powerboat, you are not too concerned with battery life when the engine is switched off, but it's always good to do a quick sanity check. Capacity is measured in amp-hours, which is current * time. Therefore time=Capacity / Current. I suspect for this case you will be driven by the starting requirements of the engine, but it is a good idea to make sure you can run everything for a few hours with the engine off. This is especially important if you are off-shore, where having a working radio is critical for safety reasons.

    Once you've done that, you can have fun drawing up a wiring diagram. There are plenty around for different boats. What your diagram looks like will be dictated by the kit you've got. There isn't very may rules for a good wiring diagram but the following are important:

    1) Keep it simple
    2) Use different colours for different voltages and power/signal lines.
    3) Keep high-power cables as short as possible.
    4) Write the rating on the diagram. ie. signal (milliamps), 5A, 10A etc.
    5) Don't skimp for cost, marine electronics is not somewhere to save money excessively (but some kit IS overpriced, so be aware).

    It is quite a good idea to do as much of this as you can on computer. There are loads of free drawing tools and circuit design tools (Qcad for 2D drawing and Kicad (electronics) are two that spring to mind). When you have done it, keep a copy at home, and keep a laminate copy on the boat (I'll bet there's not many who do the latter). It's probably a good idea to keep the datasheets for as much equipment as you can with each copy of the electrical documents. They should be available for most kit.

    By the time you've gone through this procedure you will probably have a small book for the electrical system. This is a good thing. It shows a well thought out system, and because it has been documented properly, it's easy to work on.

    Hope the long post doesn't put you off :) It's a lot of work, but it IS worth it. Samples of global wiring layout and switchbox detail (from my 14ft racing yacht) are attached. I will post a further diagram later, showing the full circuit layout.

    Tim B.
     

    Attached Files:

    1 person likes this.
  3. Tim B
    Joined: Jan 2003
    Posts: 1,438
    Likes: 59, Points: 0, Legacy Rep: 841
    Location: Southern England

    Tim B Senior Member

    Wiring diagram attached. This is a very simple system, but it shows the basics.

    Cheers,

    Tim B.
     

    Attached Files:

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