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Kevin,

Could you please check out my homemade boat wiring diagram? It’s for my 17.5′ Crestliner Fish Hawk.

As you can see, I added and wired the two Attwood battery selector switches and a fourth battery to the system (Battery 2) and wired all the batteries in parallel. I also added the Blue Seas fuse block, all lighting, fishfinder, trolling motor, etc.

Click to Enlarge

My goal here is to be able to run the trolling motor off the extra battery if needed and/or to be able to start the motor with the extra battery if the main died. Also, to run all the lights off the extra battery for night fishing. I’ve yet to turn both switches to “both” because I’m not sure if that would be bad for……..everything.

I’m obviously an amateur at this so was wondering if you think it’s a safe setup assuming all the fuses, connections, wire gauge, etc. are kosher? I haven’t had any trouble yet but I’m a little nervous about burning something up.

I’d really appreciate your input if you can decipher the wiring diagram.

Thanks,

S.D.

Hi,

I would make a couple of minor changes:

• Move the trolling motor circuit protection to the trolling motor side of the switch.
• Add circuit protection for the Blue Seas fuse panel at its connection location to the boat battery switch.
• Use the same size boat battery cables for all of your battery link wires. You call out 4/0 for the positive lead (I would assume you mean 4 AWG) but not on any of the other cables.
• If the trolling motor batteries are near the bow of the boat I would consider adding circuit protection at each end of this wire to help reduce the risk of a catastrophic fault.

Hope this helps,

Kevin

Kevin,

Thanks for the help Kevin. I’ll do all of that.

Also, I was wrong about the battery cable being 4/0, its actually 1/0 welding cable.
Thanks again,

S.D.

Hi,

Most people don’t use welding cable on boats or cars because it is not oil resistant.

Kevin

Hey Kevin,

Your site is amazing. Thanks for all the info.

Now here is my boat wiring question:

We have a Native 14.5 ft Kayak. It only weighs 75 pounds and wish to power it with a 12 volt Motorguide trolling motor on some of the quieter lakes for fishing.

What are the battery options? Will a 24 volt with 93 amp hours work? And for how long? From reading your posts I learned we need a better charger than the 25 year old trickle charger we have, any gems you recommend?

Thanks again.

Hi,

Most of the time, you don’t want to discharge a boat battery below 50%, so you are only going to use 46 of the 93 amp hours available in the battery. The small, 30 lb thrust trolling motors draw about 30 amps at full power. At wide open, you can expect the battery to last about 1.5 hours. A 5 amp charger would take about 9 hours to recharge the battery after use.

Hope this helps,

Kevin

Kevin,

Could you please tell me the best place to find an oddball boat wiring harness? I need one that will fit a Johnson 75elr78c engine from the red plug in the ignition switch?

Thank you for your help.

Hi Bill,

I’m sorry, but neither of our wiring sites have anything like this. If it were me, I would try ebasicpower.com.

Good luck,

Kevin

Kevin,

I recently bought a 16 foot Smokercraft fishing boat with a 60 hp Mercury EFI 4 stroke engine. I also bought a stereo unit for the boat and was hooking it up and now I have 3 problems.

• No power tilt and trim
• No turn over of the engine with the key start
• No power to my fish/depth finder.

I have checked the fuses. Both the one of the engine as well as the one on the fish finder.

I ordered a key switch unit and a 20 amp circuit breaker. If this does not fix the problem—do you have any suggestions of where I should look next?

All of the above worked before the stereo hook-up in which I connected the power cable to the ignition.

Thanks for your help!

Leroy

Hi Leroy,

There must be a blown fuse somewhere on your boat. Is there an in-line fuse at the key or an ignition fuse on the fuse panel?

I would use a meter or test light to look for 12 volt power at the key switch and make your way back to the engine.

I don’t believe a new key switch is going to solve the problem.

Let me know,

Kevin

Kevin,

My boat’s navigation light switch is spliced into the negative wire.

Is this acceptable or should the switch be rewired into the positive wire. The positive wire is fused with a 2 amp fuse.

Your help will be greatly appreciated.

Thanks

Hi,

Although it is not a common practice, there is nothing really wrong with switching the negative lead instead of the positive lead.

The best practice is: source of power, circuit protection within 7 inches of power supply, switch, device, ground.

Hope this helps,

Kevin

Hi Kevin,

When storing a small vessel on a trailer for the winter, is it advisable to connect a ground clamp to ship’s ground, ie, the zinc on the outboard?

Regards,

Robert

HI Robert,

There is no reason to unless you are doing something on-board that may produce a large static buildup such as running a vacuum cleaner.

Enjoy your winter,

Kevin

If you need more in-depth info, be sure to check out this more comprehensive guide to all things Whaler on the same site.

Both postings are really well done and should be a great resource for our readers.

Kevin,
I have a 2010 Nitro Z7. When I tried to use the navigation lights for the first time they wouldn’t work.

I checked the fuses. The fuse box isn’t marked as to which fuse is for the lights, so I had check them all. The last fuse, a 5 amp, was blown. So I plugged another 5 amp fuse in and it immediately blew.

What is my problem?

Please help

Dean

Hi Dean,

There is a short in the circuit that is causing the fuse to blow.

Trace the wire leaving the fuse panel. It should go from the fuse, to the switch, and to the device.

If the switch is not turned on, but the fuse still blows, the problem is between the switch and the fuse. If the fuse only blows when the switch is turned on, then the problem is between the switch and the device.

Hope this helps,

Dear Kevin,

I have a Marinco 12-24/24-36 plug and receptacle installed on my boat for my trolling motor.

I have switched from a 24 volt system to a 36 volt system and noted that two of the four prongs on the male plug are larger than the other two.

The trolling motor uses two wires (black and red) for power from the batteries. Should these wires be installed on the two larger prongs, since the 36 volt system will be drawing more current than the 24 volt system. The prongs are labled A+, B+, neg, and NET on the back of the plug.

Thank you for your time.

Arthur

Hi Arthur,

I would use the larger terminals in the plug for your new trolling motor. They have more contact area and will be less likely to get hot during heavy operation.

Hope this helps,

Kevin

Thanks Kevin.

That was my thoughts. Nice to have your take.

Arthur