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Author Topic:   Aluminum Boat 12-volt Electrical
fishnchips posted 04-21-2007 06:54 AM ET (US)   Profile for fishnchips   Send Email to fishnchips  
Is there any conditions I have to be aware of when installing a depth sounder, VHF radio, guages, and so on, on an [aluminum] alloy boat?I have a brand new hull which has nothing installed yet. I am doing this myself. Any help will be cool thanks guys
HAPPYJIM posted 04-21-2007 08:17 AM ET (US)     Profile for HAPPYJIM  Send Email to HAPPYJIM     
Boston Whaler doesn't make a metal boat so it might be best to try some other site supporting metal boat construction.

Here's a site I found using GOOGLE.COM It has some good stuff to read about metal boats. metal_boats.htm

jimh posted 04-21-2007 10:00 AM ET (US)     Profile for jimh  Send Email to jimh     
This discussion area is not limited to topics involving Boston Whaler boats. Also, Boston Whaler has made aluminum boats for commercial customers, although they are rare.

To the best of my knowledge--which is limited on this topic--I have never seen or read of any special considerations regarding 12-volt wiring on boats with aluminum hulls. Generally the hull will be bonded to the negative terminal of the battery through the engine block.

Probably the best source of information on this will be the recommendations of the American Boat and Yacht Council (ABYC). I do not have a good cite for that information.

Most of the devices you mention are constructed with non-conductive enclosures, and whether or not you mount them on a metal panel or a non-conductive panel makes no difference. For example, all of the gauges on my boat are mounted on a metal panel, but I have made no special provisions to bond that panel to the rest of the electrical system.

As a general rule to prevent galvanic corrosion, you want all elements of the hull and its metal fittings to be at the same electrical potential. If you are uncertain of the electrical connection between any metal components of the hull, it would be a good idea to bond them together with a suitable bonding conductor.

Whether or not it is common practice to bond the negative terminal of the battery to the hull of an aluminum boat with a dedicated bonding conductor is something which I do not know. Perhaps others can offer advice based on recommended practices in the boating industry.

jimh posted 04-21-2007 10:02 AM ET (US)     Profile for jimh  Send Email to jimh     
Also see:

HAPPYJIM posted 04-21-2007 11:09 AM ET (US)     Profile for HAPPYJIM  Send Email to HAPPYJIM     
I was a shipboard electrician on a 213 foot ocean-going tugboat for 19 months. The low voltage 12- and 24-Vdc had dedicated [negative power return] wires. They were not [bonded] to the hull.
jimh posted 04-21-2007 01:19 PM ET (US)     Profile for jimh  Send Email to jimh     
A vessel's hull should never be used as part of the power distribution wiring.

About the only place that I can think of where power is distributed and a chassis is used as the common is on a trailer; the trailer frame is used as the negative common for the lighting circuits. We all know that sort of wiring practice is very unreliable.

To get back to the original question, installation of a SONAR, a VHF Radio, or engine gauges is not particularly affected by the hull being made from aluminum alloy.

roloaddict posted 04-21-2007 10:33 PM ET (US)     Profile for roloaddict  Send Email to roloaddict     
For some radios that lack a seperate ground lug, sometimes bonding the negative lead to the hull wil improve performance. If your electronics do have a ground lug then a short stap to ground will provide a path for static and other forms of interference. I use a stainless washer between the copper strap or plated terminal lug and the aluminum.
fishnchips posted 04-22-2007 04:22 AM ET (US)     Profile for fishnchips  Send Email to fishnchips     
Thank you guy's for the help. so my unterstanding is just wireing up a buss bar for + and a bus bar for - and just connect the power from the battery to the bus bar's and i dont have to earth it, as the - acts as the earth, interference i understand as i work with ham and cb alot here in nz. just not alloy boats lol :) cheers and thanks again :)
HAPPYJIM posted 04-22-2007 09:03 AM ET (US)     Profile for HAPPYJIM  Send Email to HAPPYJIM     
Do you have a picture of your boat?
jimh posted 04-24-2007 12:44 AM ET (US)     Profile for jimh  Send Email to jimh     
If you are in New Zealand, consult with BEP. They have extensive marine 12-volt wiring devices and technical literature.
Plotman posted 04-26-2007 11:00 PM ET (US)     Profile for Plotman  Send Email to Plotman     
I had an aluminum sailboat at one point. As I recall the negative bus at the main panel was bonded to the hull. The main concern with an aluminum boat is stray voltage that turns your boat into a battery that eats away the aluminum over time. Zincs are a must.

Get a copy of the 12-Volt Bilble by Brotherton (make sure you get the 2003 version). It is a good introduction to designing wiring systems on boats.


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