Help with putting in a new ground to dash

[74corvette]

II have a 2001 SAN with a GT40 and I'm looking at putting in a bigger gauge wire for the ground running to the dash. Is it pretty straight forward or is there something I should know about ahead of time? Thanks for any instruction from someone that has done this before.

[DW SD]

in no particular order:
You should not see more than 10 amps draw with factory stereo, perfect pass, etc. at the dash. If you are running an impeller style pump and use relays wired under the dash, I'd then use 20 amps as your current for the voltage drop calculator. I use this calculator: http://www.calculator.net/voltage-drop-calculator.html
Probably obvious, but use: voltage ~ 14V, DC on the drop down screen.

Buy a busbar, blue sea systems makes nice ones for installation under the dash so you can expand in the future. doesn't need to be massive.
Something like (on Amazon) would be fine.

• ASIN: B000MMDL7K

I'd run something like 4 gauge. That should be overkill and not terribly expensive, unless you are wiring very large stereo amps from the dash. If you do run big amps from there, determine their potential load and add in to the voltage drop calculator and size the wiring accordingly.

use a voltage drop calculator online to check. Aim for less than 2.5% voltage drop in sizing your wiring.

use adhesive - lined shrink tubing on both ends.
used tinned lugs on both ends, too. (vs. plain copper).

[vanhanbr]

I'll add a few things:

I think 8 gauge would be sufficient.
Busbars are they way to go.
You have to redo the positive not just the negative power lines.
Use marine tinned wire as well as tinned lugs.

Look for the post by Jeff when he redid his ski Nautique, he did a real nice job on the wiring of the dash and used factory colored wire to make everything easy to follow.

[74corvette]

Got everything taken out tonight to get to the fuse box. Have a couple questions.
1) The positive and ground are running underneath through the ski locker, is it ok to run them along the side under the gunwale instead of below?

2) I'm replacing the ground and positive on the fuse box, any other wires I need to replace with larger gauge?

Thanks for the help

[DW SD]

I see no reason not to run under the gunwale and did similar for my wiring for my Hydrophase speed controller.

[DW SD]

I might route some heavier gauge from the fuse box up to under the dash, especially if you've added any other accessories there.

BTW - I did a few calculations using the above voltage drop calculator. If your dash ends up drawing 25 amps, with 30' of wiring. That's 15' each positive and negative (back to the battery), voltage drop with 8 gauge wire is estimated @ 7%. That does not even include voltage loss in distribution to the various devices.

And 25 amps doesn't seem extreme, give: Perfect pass draws 5 amps-ish. 60 Watts of stereo would be another 5. A bilge pump, 7 amps, ballast pump, 7. running lights maybe 5 or so.

Given the amount of work, I'd steer you towards spending a few more $ on heavier wire, itself.

[74corvette]

Thanks for the reply DW SD, I run a two battery system with a battery isolator in between. The second battery has the 2 Johnson pumps and the stereo equipment the other one just has the dash and starter. I am currently installing 4 gauge wire for both positive and ground. The wire is from 2 different companies so one is a little smaller then the other one. Will this cause any problems or do you think I'll be fine?

[DW SD]

Hi,
Glad to help!

Couple of thoughts:

1. In the end, voltage drop is additive, so I think you'll find an improvement over your present setup even if one of the new wires is slightly smaller. In my view, 4 gauge should be 4 gauge even if the insulation has a different thickness.

2. Do you have a digital volt meter? If not, it would be a good tool. Harbor Freight sells a cheap one for about $10. I recently compared voltage readings between that and my Fluke (more expensive professional grade tool) and at least for DC, the they were in sync to 4 digits of resolution. In fact... I bought this one to leave in my RV. $6.00 well spent! http://www.harborfreight.com/7-funct...ter-98025.html

3. The batteries should be all connected, I'd think, under charge, which I'd assume is when the stereo and the ballast pumps would primarily run. Some folks would run everything from one and keep the spare battery in case they get stranded. Others might tie them together and create a scenario where they'd be less likely to become stranded. On high end motorhomes, the coach batteries are separated from engine start. And the start batteries are only used for that. It sounds like you employ this strategy which makes sense to me.

4. If you have a digital volt meter, you could take a few measurements. I might suggest having both batteries off and measure their standing voltage at least 12 hours after you last ran the boat. If both are at 12.7 to 12.8 volts, I'd say what you are doing is working.

5. It'd be an interesting exercise to take some voltage samples while the boat is in use, too. This could help tell you determine where you might need heavier gauge wiring, in addition to what you are already doing.

6. Curious, are the ballast pumps wired with relays and powered from the dash? If considering an upgrade here, I'd use waterproof relays but drawing power from either the rear batteries, maybe the isolator, or from the alternator 12V+ lug to feed the pumps. (you still should use a circuit breaker or fuse to be safe) Not running power wires long distance would (to dash and back) would eliminate some of the loads at the dash and need for heavier gauge wiring. The only wires running to the pumps would then be the trigger wires coming from the helm. Triggers are very low current draw <1.0 amp to energize the relays.

The wiring upgrade you are making should be a good improvement and more might not be necessary..... So I'd recommend don't fix it if it isn't broken. :-) Then again, I'm all about making sure I prep my boat to enjoy the time on the water and not have to fix something on the fly.

Hope that helps and that my response doesn't further complicate!

[74corvette]

DW SD, I currently have the 2 ballast pumps wired right to the battery so they can be run without the boat being turned on. Can you walk me through which relays I need to get and how to wire them up? Thanks

[DW SD]

Sure I could draft a wiring diagram. How are the pumps presently switched and configured? Also, do they operate independently each filling and draining different ballasts?

In my 2001, I use the original dash drain fill buttons to operate my pump.

[74corvette]

I have

[74corvette]

Sorry, phone accidently sent it. I have 2 Johnson pumps, one fills the front and ski locker bags through a directional valve. The other pump fills both rear bags. I got each pump running off the switches I got from Wakemakers and wired them how they instruct to wire up the pumps to their switches. Let me know if you need any other information. Thanks again for the help. I got the positive and ground wires installed last night and notice an improvement over the stock wiring.

[DW SD]

I would follow wake makers instructions on the pumps. Given you have two separate systems, I don't think it makes sense to use the stock buttons as I'm guessing fill / drain times are different per ballast zone.

If you have a digital volt meter, you could measure voltage at the pumps under load. If the voltage drops far below that of system (say 13.5 or 14.0 while engine is running) then you might see improvements from installing relays for the pumps.

I have faith in wake makers and actually went to their site to see if there are wiring diagrams for their pumps to reference.

Hope that helps. And glad to hear you have an improvement following the heavy - gauge wire upgrade. That always feels good!

Curious, what metric do you use for improvement? Is that dash volt meter voltage increase? OR?

cheers,

Doug

[74corvette]

I forgot to check before and after voltage with my meter, but the main thing is when I used to turn on the blower, the voltage would drop 1.5 to 2 volts. Now the needle barely drops and this is with the engine not running. I also have the upgraded 100 amp Alternator which I forgot to mention. Thanks again

[DW SD]

You are welcome!

Yeah, the dash-mounted voltage gauge is a good indicator. I get a pretty significant drop when my impeller - ballast pump runs. Maybe 1 to 1.5V on the dash gauge. Unlike your setup, the pump was wired prior to my ownership to run from the dash vs. have relays close to the pump. No big deal, but I think yours is optimized.

Thankfully, the PO did a very nice job of upgrading the wiring in my case, including using large relays, heavy gauge wire to the dash and properly installing fuses in the dash.

In short, I won't be messing with mine .... unless it breaks.