Re-Wiring Boat & Have A Couple of Querries

[ryangler]

HI Guys,

i'm working through planning the rewire of my boat and have tabled everything that will draw power totalling 300 amps. Now unless I'm sinking at night with all the lights on, using the deckwash, whilst playing with the trim tabs, pulling the anchor, with the auto pilot working all while the stereo is turned up to the max, im not going to pull this many amps. I've played with a couple scenarios and it seems I"m going to draw the most amps whilst pulling the anchor at night with a few lights on and the electronics or around 125 amp max.

There are alot of stand alone winch wiring kits on the market to retro fit winches. Instead of taking the winch wiring all the way back to the batteries at the stern I wanted to run heavy cable to a power distribution point (bus bar) in the cab with an inline 150A breaker. There I will branch out to a couple 12 gang fuse boxes.

Is there any reason to keep high amp items like an anchor winch seperate from remaining electrics/electronics?

Also I have already run some 2 b&s cable from the transom to the cab for the amp which was overkill beause I had previously planned to run a second amp/speakers/sub. I plane to run a second cable to make up the short fall in cable size to use what I have already got. Any reason why this isnt a good idea and i should just get some appropriate size cable.

Cheers

[scottar]

Only reason I can think of is voltage drop if the cables are too small - which in most rigs they are (possibly the reason for no shortage of wiring looms). That said, if you are going to duplicate the feed anyway, why not make one for the winch. A single 2B&S pair should run the rest without issue I would think.

[Dignity]

HI Guys,

There are alot of stand alone winch wiring kits on the market to retro fit winches. Instead of taking the winch wiring all the way back to the batteries at the stern I wanted to run heavy cable to a power distribution point (bus bar) in the cab with an inline 150A breaker. There I will branch out to a couple 12 gang fuse boxes.


Cheers

Maybe I have misread this but if the 150 amp breaker is before the 12 gang fuse box then when it trips while you are retrieving the anchor everything else drops out. I have had a situation where lifting the anchor tripped the overload, I would keep the anchor winch totally separate and would be much easier later in life tracking back any issues.

You've got me thinking though that an LED light for the anchor winch on the bow is a good idea.

[VictorOscar]

Hey ryangler,

The only reason I can think of isolating high drawing such as your anchor winch separate is to prevent them from potentially disturbing your other circuits (I think it's called a voltage spike) when you operate them (though this is probably rare).

[ryangler]

Thanks guys

So the oversize wire I previously installed to the amp is a 1 AWG gauge (42.4mm2 wire). Working on 150 amps over a 7m / 23ft run (6.75m actually) the Blue Sea circuit wizard calc recommends 0 gauge (53mm2 wire) where as their chart recommends 2/0 gauge (68mm2 wire). General consensus seems a max volt drop of 3% is acceptable for critical items and in the automotive industry 5% is widely used. If I type the same information into a voltage drop calc on Calculators.net (150 amps, 6.75m, 12v, 2/0 cable) it gives a voltage drop of 4.33% but the Blue Sea chart states it allows a voltage drop of max 3%

I have 14.5m of 1 AWG left on the 30m roll from before so I'm going to just run another length to just inside the cab where the amp was mounted. If I put 75 amps (half load considering 1x 1awg cable), 6.75m, 12v, 1 AWG into the calculator I get 3.42% voltage drop. Realistically the max amps will likely be 130 amps, hypothetically pulling anchor with music playing, someone using the deck wash to clean the bait board and lights going). So if I punch in 65 amps, 6.75m, 12v, 1 AWG into the calculator I get bang on 3% voltage drop so this will work well.

The plan
- 4 lengths of 1 AXG running under the gunnels to the back side of the cab wall to a 1x positive and 1x negative through panel terminals with a 150amp breaker in line.
https://www.bluesea.com/products/220...ds_%5BBlack%5D
https://www.bluesea.com/products/708...nel_Mount_150A
- From there I will run to a pair of 12 gang Blue Sea in the cab connected to the front side of the panel terminals and branch out from there.
https://www.bluesea.com/products/503...Bus_Fuse_Block
- For the amp I will run from the back side of the panel terminals (600mm) with an inline fuse
- For the anchor winch I will run from the back side of the panels terminals (2800mm) with an inline 80amp breaker that comes with the winch
- NMEA and transducer cable down other gunnel to keep it all separate

And that should do it, keeping it all neat and tidy.

http://circuitwizard.bluesea.com/
http://assets.bluesea.com/files/reso...on_chartlg.jpg
http://www.calculator.net/voltage-drop-calculator.html

[scottar]

Having the two feeds forward - load share - winch and one distribution block off one and the other blocks off the second. Only extra required is a second heavy breaker and distribution post. Split the circuits so that not all your lights are running off the one feed and try and keep "sensitive gear" off the main that is supplying the winch. Then again, if your stereo amp is drawing that much power, yours ears will be bleeding anyway - being in the dark or pulling the pick will be the least of your concerns. Make sure the breakers for the mains are down the back of the boat and you have very good chafe protection for the cables.

[ryangler]

Scottar, so load sharing is a no no? just to confirm you recommend using the existing 1 AWG for everything except the winch and then run another length of 1 AWG for the winch and keep it separate? and 80amp breaker for winch (included in winch bundle) and another 70A breaker for the other run. The batteries to the winch is 9.55m and 80 amps over that distance with 1 AWG is a voltage drop off 5.17% so I would have to purchase different cable.

I suppose I could pop into the local auto sparkie and see if he will do a swap plus cash for some heavier 3/0 gauge cable.

[peterbo3]

Could I suggest running your winch feed directly off your "start" battery. A BEP VSR or Blue Seas ACR will isolate the start battery from the house battery when using the winch plus quickly recharge it as the VSR or ACR will sense the voltage drop & all your alternator output will go to the start battery. With the winch feed coming from the start battery you will eliminate any voltage spikes to your GPS, sounder, etc.
Electronics are more resilient as far as voltage spikes go these days but if you can eliminate them do so.
If you are in Brisbane try Marshall Cameron at C.E.C.A for heavier cable. Tycab tinned & he normally has some off-cuts on hand. 38651122 - Geebung.
For heat shrink terminals & tube please take a look at my sig block.

[scottar]

Scottar, so load sharing is a no no? just to confirm you recommend using the existing 1 AWG for everything except the winch and then run another length of 1 AWG for the winch and keep it separate? and 80amp breaker for winch (included in winch bundle) and another 70A breaker for the other run. The batteries to the winch is 9.55m and 80 amps over that distance with 1 AWG is a voltage drop off 5.17% so I would have to purchase different cable.

I suppose I could pop into the local auto sparkie and see if he will do a swap plus cash for some heavier 3/0 gauge cable.

No I was suggesting rather than everything through one cable, run your sensitive circuits through one (electronics, essential lighting etc up to the capacity of 2 of the 3 junction blocks) and use the other for the winch and the rest. I would be very surprised over that distance if 1AWG gave enough voltage drop to create issues when using the winch given it is or at least should be standard practice to have the engines running while doing so to motor up so the strain is taken off the winch. Most boats in the 6 metre range, mine included use anything down to 8B&S without issue for a "standard" sized winch for the vessel

Fit one main breaker at the back of the boat to protect each positive main. Forward you have your distribution gear and the 80 amp winch breaker.