15 ft. Alumnium Blue Fish Pro Bass Boat Wiring Inquiry

Hello, all,

I've been doing some work on an old 15' aluminum boat with a 1999 40 hp Mercury 3-cyclinder motor ; touching up the interior, replacing the plywood deck, reforming the console, etc. And now I'm at the point where I need to wire in bow/stern lights and a plug for a trolling motor so that I can put it up for sale.

The specs of my electrical system are: I use 2 batteries that are connected via a Blue Sea Systems Battery Link ACR (ACR link:http://bluesea.com/viewresource/59) & from that system I run one 12 ga positive wire to the positive bus of my control panel. Then, from each negative pole of the 12 volt batteries, I run 2 ground wires to my negative bus bar. (There's also a ground for the acr that goes to the neg bus bar).

Ultimately, I'm wondering if I need to splice fuses into each of these wires (even the grounds?), & also I'm open to any basic suggestions anyone can offer in regard to what I should keep in mind/be familiar with as I'm wiring the lights & trolling motor plug in.

Thank in advance,

Ken

 

No you do not need to fuse the negatives. But you do need to fuse the positive. The requirement is that any wire should be fuse within seven inches of the source of power. The battery is the source of power for the positive buss. So the fuse has to be sized for the full load carried by this positive wire. The positive buss then becomes the source of power for everything down stream. So you need to fuse wires leaving your control panel sized to the load each wire carries.

I do not understand why you have two ground wires to the negative buss. How about posting a diagram of the system so we can see what is going on.

 

You have 72" to the main wire of the battery.

See below diagram. Anything electrical within 7" of a battery will become corroded in a average boat.

 

How about.

You writing a list of all the things on the boat that will need electric.
Then we can come up with a layout that is simple for resell.

Legally, you can just replace each part with a very similar part as a maintainance repair. Rather then a complete USCG approved type of setup. Electric stuff costs lots of money in a hurry.

 

The rules are (from the regulations)

Sec. 183.455 Overcurrent protection: General.
(a) Each ungrounded current-carrying conductor must be protected by a manually reset, tripfree circuit breaker or fuse.
(b) A manually reset, trip-free circuit breaker or fuse must be placed at the source of power for each circuit or conductor except:
(1) If it is physically impractical to place the circuit breaker or fuse at the source of power, it may be placed within seven inches of the source of power for each circuit or conductor measured along the conductor.
(2) If it is physically impractical to place the circuit breaker or fuse at or within seven inches of the source of power, it may be placed within 40 inches of the source of power for each circuit or conductor, measured along the conductor, if the conductor is contained throughout its entire distance between the source of power and the required circuit breaker or fuse in a sheath or enclosure such as a junction box, control box, or enclosed panel.

Sec. 183.460 Overcurrent protection: Special applications.
(a) Each ungrounded output conductor from a storage battery must have a manually reset, trip-free circuit breaker or fuse, unless the output conductor is in the main power feed circuit from the battery to an engine cranking motor. The circuit breaker or fuse must be within 72 inches of the battery measured along the conductor, unless, for boats built prior to August 1, 1985, the circuit has a switch that disconnects the battery.


I'm sorry, but where you got the idea that anything within seven inches of the battery will be corroded is simply not true.

All he wanted to know, is does he have to fuse the positive and negative wires. The simple answer is yes on positives, no on negatives.

 

Ike

Look very carefully at the + battery post of my USCG wiring diagrams. IF IF you run a MAIN 12 gauge wire from the battery post. It can be legally 72" long . The fuse or breaker must be at or before the 72" end of the wire.
That does allow a fuse or breaker panel to have a single lead back to the + battery post.

You are stating the 7" or 40" requirement. If you tap a lead off of a disconnect switch that is part of the heavy cable running to the starter motor circuit. Or if tapping off of the starter motor main terminal.

 

I helped draw those diagrams.

The rule for 72 inches is (quote from ABYC Standards
2. If the conductor is connected directly to the battery terminal and is contained throughout its entire distance in a sheath or enclosure such as a conduit, junction box, control box or enclosed panel, the overcurrent protection shall be placed as close as practicable to the battery, but not to exceed 72 inches (1.83m).

So if he wants to go 72 inches then the conductor has to be in a sheath, such as wire loom or conduit or inside an enclosure such as an electrical panel.

Here's the explanation from the USCG Boat Builders Hand book

The figure you are showing above is the Fig 25 from the USCG Boatbuilders Handbook that is referred to above. The ungrounded conductor is the positive wire.

 

1 VERY important fact of Aluminum boat hulls is they are avery good conductor of electricty. SOO I would NOT use the metal of the hull as the - return of anything. First reason is the obvious one. Any + lead or cable that accidently shorts to the hull below the water line can easily start a sinking.

Another bad thing is the current running thru the hull CAN CAUSE the hull to become a battery & get eaten away by Galvanic action.
For things like a bow light or horn # 16 guage wire is plenty. A bow anchor of 20 # weight is in the # 14 size. Only because a hung up anchor pulls easily into the 10 to 20 amp range while struggling to lift. BOTH wires of the anchor DO become + & - as the anchor is run up & down.
Fish / minnow tanks... general lighting... should be in the #16 guage range.
On my 16' Aluminum Lowe I drilled a hole into the top round tube to carry all the wiring from various equipment..................CAUTION.........DO NOT DRILL anywhere there is no Aluminum plate welded onto the tube !!!!! I drilled into the tube UNDER the the triangular 9" x 9" bow reenforcement plate & under the stern corner 9" x 9" reenforcement plates...........More EXTREME caution........ the holes drilled into the top tubes.....REQUIRE EXTREME thought about the size & shape of the opening to run the wire in.

My holes are centered & about 1/2 OF THE DIAMETER OF THE TOP TUBE DIAMETER. To gain enough opening to put all needed wires into the tube I made the opening 2" long UNDER THE PLATES. Put some of ...Electrical Splicing Pads.... Around the sharp edged oval opening edges......Buy it a HD / Lowes Or a real electrical store...........

You MUST carefully cover the edges of the Aluminum holes......No excuses or shorts WILL HAPPEN.

I BEGGED all the wire & splicing pads from a professional electrican. Guy could not help me enough. Used THHN plastic coated wire. It is a stranded wire. Brought him Coffee & Dough Nuts. Great guy.

I used those cheaper black fuse strips to protect all the equipment in the boat. See a left over piece from a larger fuse strip in the picture below.
Caution. I did run the NOISE sensitive negative wires DIRECTLY to the stud on the - battery post. Some wiring of boats get away without doing that. I had the time & 15 cents to run them to the battery post. Most people do just fine by installing a 1 piece - buss bar for all the - leads.

 

Cyclops is right on. Never use the hull as a conductor. Bad things can happen.

 

Wiring Diagram

Thanks for all the help, fellas. I can see this thread has taken on a life of its own, but I have a few more questions/details to offer to the conversation.

First, my wiring diagram should show up - If so, you'll be able to see that I plan to wire in 3 switches (2 for the lights, 1 for trolling motor; I know I could easily connect the lights together behind one switch, but for my purposes (I don't want to buy another positive bus bar today) I'm just going to separate them. Having said that, feel free to offer suggestions/advice in regard to the set up & feel free to ask for clarification if anything on the diagram is unclear.

Thanks!

** I just noticed that I didn't draw in a ground wire for the small neg bar on my control panel- I will be including that.

 

Considering the load on a trolling motor, you'll need a relay to shunt the 12 VDC load to the motor without going all the way to and from a switch.



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