Welding cable or battery cable for windlass

[pvb]

Nobody has mentioned that welding cable isn't tinned. Tinned cable is much better in the marine environment as it resists corrosion considerably better than it's untinned counterpart.

Unless the boat is absolutely swimming in water inside, it won't make any difference.

 

[The engineer]

Use heatshrink sleeve with integral hot melt glue to seal the copper tube terminals on untinned cable. Whilst not conforming to ISO standards it will be good for years to come.

Tinned welding cable available here if required: http://www.kojaycat.com/Tinned Battery.htm

 

[oldsaltoz]

Your local scrap yard will have welding cable off cuts.

 

[Simondjuk]

There are lots of boats out there with 30 year old untinned but still perfectly functional wiring in them.

 

[nigelmercier]

Tinned cable is much better in the marine environment as it resists corrosion considerably better than it's untinned counterpart.

This is a valid point. But even if tinned cable is used, then the ends should be made waterproof with heat-shrink and contact grease.

 

[greenalien]

It would be poor installation if the engine had to run to boost the volts because the cable to the anchor windlass were not heavy enough to power the windlass without

The other problem with using undersized cable is that it will heat up, possibly quite a lot - if it drops 2 volts, at 80 Amps current draw, it will have to dissipate 160W of power as heat.

 

[prv]

There are lots of boats out there with 30 year old untinned but still perfectly functional wiring in them.

Maybe, but on the other hand my boat at half that age had untinned and horribly corroded wiring throughout. Now replaced with tinned.

if it drops 2 volts, at 80 Amps current draw, it will have to dissipate 160W of power as heat.

And that's about the size (or bigger) of many electric greenhouse heaters (those tubular ones). Would the OP pack one of those away behind his headlining or bunks?

Pete

 

[VicS]

The other problem with using undersized cable is that it will heat up, possibly quite a lot - if it drops 2 volts, at 80 Amps current draw, it will have to dissipate 160W of power as heat.

That's right. Although 160watts dissipated along 10m of cable for short periods may not be a problem.

There are two factors to take into account when sizing such cables. One is the volts drop on long cable runs. (Long probably means anything over about 2 metres.) The other is the safe working current which applies whatever the cable length.

There is a conservative rule of thumb which says that for safe working cable should be 700 circular mils per amp. (1 mm² = 1.974 x 10^9 circular mil) which gives a minimum safe cable size for 80 amps somewhere between AWG 2 (33.61mm²) and AWG 3 (26.65mm²)

 

[GrahamM376]

Is it ok to use welding cable for wiring up the power to an electric windlass? The length would be about 10 meters from the leisure batteries (through a circuit breaker) to the windlass. I assume the alternative is battery cable but this looks expensive. Steve

Welding or battery cable are both OK, one's more flexible than the other so sometimes easier to work with. The manual should state the cable size required for different lengths but remember when measuring, it's the distance there and back, not the distance from battery to windlass. I'm not a lover of batteries under bunks in the forepeak, have always used runs from engine battery (not domestics) as the engine is usually running when hauling.

 

[snooks]

I'm not a lover of batteries under bunks in the forepeak, have always used runs from engine battery (not domestics) as the engine is usually running when hauling.

I took my windlass power from my domestic batteries.

I don't like the idea of anything but the engine being attached to the engine battery. I have a VSR so when the engine is running and has charged the engine battery it links to the house battery and charges those. Most of the time the power is coming from the batteries/alternator. But if my engine fails I still have power to get the anchor up/down and a full engine battery for starting after I've attempted to repair it.

 

[prv]

What's with this assumption that everyone always motors in and out of anchorages?

[/stir]

Pete

 

[snooks]

What's with this assumption that everyone always motors in and out of anchorages?

[/stir]

Pete

Just because my engine is running, it doesn't mean I'm using it

 

[prv]

Just because my engine is running, it doesn't mean I'm using it

Seems like the worst of both worlds

Pete

 

[snooks]

Seems like the worst of both worlds

Pete

Not if something goes wrong

Something like a halyard going, wind dying, sheet jam, underestimating the tide etc.

Besides I like to check I'm not going anywhere with a big motor astern once I'm anchored.

I'd rather have the engine running and to hand if I need it then realise I need the engine and have to go below/reach into the companionway to start it.

 

[GrahamM376]

I took my windlass power from my domestic batteries.

I don't like the idea of anything but the engine being attached to the engine battery. I have a VSR so when the engine is running and has charged the engine battery it links to the house battery and charges those. Most of the time the power is coming from the batteries/alternator. But if my engine fails I still have power to get the anchor up/down and a full engine battery for starting after I've attempted to repair it.

With the engine running, my alternator is producing more power than the windlass is drawing so, it's not going to flatten the engine battery. Even in the unlikely event the engine battery was low, I can switch in 500AH of domestics anyway.

 

[Conachair]

Not if something goes wrong

Something like a halyard going, wind dying, sheet jam, underestimating the tide etc.

Besides I like to check I'm not going anywhere with a big motor astern once I'm anchored.

I'd rather have the engine running and to hand if I need it then realise I need the engine and have to go below/reach into the companionway to start it.

+1! No point pushing your luck. I've done it engineless, too stressful!

As for battery up front, wouldn't it be possible for the alternator to shove 80 odd amps up the cable anyway? (assuming a big alternator) So you would need beefy cable anyway?

 

[GrahamM376]

What's with this assumption that everyone always motors in and out of anchorages?

[/stir]

Pete

Agreed not everyone does but most do, especially when crowded with little room for cock-ups.