Installing a windlass

[firstascent2002]

Hi guys.

I've got a 500W plastimo windlass that uses up to 60A whilst running. I plan to run cables from teh existing 110 AH domestic battery under the chart table forward. I know that I'll have to have the enging running when I use the windlass. The run fromt he chart table to the windlass control box is going to be around 8 m. What thickness of cable do I need to run forward? Also, any pitfalls that I need to avoid!

Jamie

 

[captainslarty]

Hi, 35 circ mils will be fine for that. It is used for such a short time you would probably be ok without the engine, normally you will have the engine running anyway.
Pitfalls ? use a 100A fuse at the battery end, clip the cables, avoid any sharp bends and make sure the cables are not going to chafe, use flexible cable and crimp connectors, apply vaseline to the connectors, use connector boots if possible

Hope that helps

 

[alan006]

There is a handy table for calculating cable size on the Aquafax website as follows
www.aquafax.co.uk/images/aceimages/Amp-Distance_DC.pdf
If I have got your figures right I think you need at least 50mm
sq cable for the job. Borrow a heavy duty crimper if you can to get good connections on your cable ends.
Good luck.

 

[oldsaltoz]

Cable:
You can use the cable from welding machines, check out your local scrap yard, then get your local auto electrical outlet to attach the required closed lugs for both ends.

Fitting;
Make sure the deck area is strong enough and has a good backing plate (avoid timber, it rots); backing plate should be bedded to spread the load.

Protection;
The environment inside an anchor locker is very aggressive, salt, mud, very high humidity etc, Talk to your auto electrician about a good quality coating for the underside of the winch and it's connections.

Install a fuse as per manufacturers recommendations.

Make up a cover to protect the winch and your toes.

Andavagoodweekend......

 

[DaveS]

No serious quarrels with Captainslarty's advice, but I would suggest:

1. To correctly calculate the volt drop you have to consider the complete circuit length from battery to windlass, not just the control box, (and the return path, depending on the tables used). Under heavy load the volt drop is likely to be significant unless your cables are seriously big (e.g. welding cable), and this could make the difference between getting a well-buried anchor out or failing to.

In most normal cases it won't be too critical because the windlass will not draw anything like its design load. Personally, I would prefer to know that when the proverbial hits the fan it will always work, but its an engineering decision in principle no different from choosing a light tall rig that will drive the boat well in light wind at the expense of early reefing and more anxiety when it really blows hard.

2. I would personally prefer a circuit breaker for circuit protection. Having had my breaker trip under extreme load (raising a very well buried anchor after a F9) I can confirm that pressing a button to reset it is a lot easier than replacing a fuse (100A marine fuses tend to be bolt-on jobs). OTOH if you're hooked fast you're not going anywhere so maybe time's not an issue...

3. I would favour supplying the windlass from the starter battery rather than the domestic, since it's more likely to have the high CCA rating suitable for the duty (a windlass is quite like a starter, really.) While I would agree that there should be no need to run the engine while operating the windlass, in practice it will probably be on and ticking over; in any event even drawing (pessimistically) 60A for 5 minutes, the windlass is only going to take 5Ah so sailing off the anchor shouldn't compromise starting ability too much.

4. If you don't like the answers from the volt drop / cable size calcs. in 1., it is only fair to point out that an alternative is to install a dedicated battery closer to the windlass. That has its own problems, including the need for both-ends protection of its charging circuit, but does give you another battery which could in an emergency be used for other purposes.

 

[captainslarty]

Hi all
Ref cable sizes, the 35 circ is no problem for a windlass in intermittent use, The engine is in use 99 percent of the time in normal conditions whilst anchoring, the voltage drop is minimal, on engine the voltage is likely to be around 14 to 14.6 volts depending on reg and battery type. for the first few minutes, otherwise around 13.6. There is no safety issue at all.
Good point re the welding cable too, excellent stuff.
Even with the engine off the voltage drop at 60 amps is neither here nor there, if everyone used 'calculated' cable sizes (usually American standard) then our kilowat winches would be supplied by cable as thick as your wrist lol.
Re the dedicated battery, this is usually more trouble than it is worth imho.
Joe

 

[alan006]

In practice I won't dissagree with the 35mm cable. As you know the cable size is for a constant rating not a short burst as might be more typical for a windlass. However it might help less experienced people to know there is a method for working out the cable size and you need to know what you are doing if you do not follow its guidelines.
I would only use a dedicated battery if there was a very long distance from your exsisting batteries to the windlass as you will need to redesign your battery charging systems to cope. Not worth it normally.

 

[Salty John]

Calculated size by American standard gives 37 circ mills for allowable 10% drop on 60 amps for 50' run. Size 4 cable.

 

[alan006]

This has raised a very interesting point, I wonder if someone on here knows the UK regs on recommended maximum voltage drop. I thought we were usually simular to the USA but I think that 10% drop would be above the UK recommendations. I had a look in John Payne's book "The Marine Electrical and Electronics Bible" and he says ideally on a 12v system 3% or 0.36 volts is a maximum. The difference between 10% and 3% is expensive when you price up the cable. Any sparkies out there know the answer?

 

[Salty John]

The American regs give two voltage drops - 3% for items likely to effect safety such as nav lights, some electronics, bilge pumps and 10% for non-critical items such as cabin lighting. I assume a windlass would be deemed non-critical and therefore I read off the 10% drop table.
As you say, there is an expensive difference in wiring to accomodate the two levels of voltage drop - at 3% maximum drop the cable size for this windlass would be 0/2.
The formula is 10.75 x current in amps x (round trip length in feet divided by voltage drop permitted in volts).
All the above from Charlie Wing's book on boat wiring.

 

[Salty John]

Of course the answer to the formula above is Circ. Mils.

 

[ShaunG]

There is a slightly different way to install the electricity for your windlass that you may wish to consider. You can install a battery near to your windlass (under Forepeak) and use heavy cable for a short run, should be min 35mmsq for upto 4m, you can then charge your windalss battrey from your main battery bank using a battery to battery charger, sterling make one as well as a couple of other manafacturers. The battery to battery charger is installed with much small cable and makes the fitment easier and the cable cheaper. On any boat over 32ft it nearly always seems to work out cheaper using the battery to battery charger route than buying long lengths of 50sqmm or above cable

 

[Danny]

I used starter motor cable from an automotive spares shop and also sourced the terminals from them. The cable comes in red and black. I soldered the terminals to the cable ends. Don't know if this is 'good practice' but it worked well for us.

 

[blackadder]

Hi,
The windlass in our boat is installed (not by me- probably from new 18 years ago) using 35mm sq welding cable. There is a 70A breaker at the control box in the engine bay, and it runs of the engine start battery. The cable run is about 11m long. It all seems to work well though I have not given it a hard time and we only go the boat this season.

There was only a control point for the windlass in the cockpit - so I wired a second control point up forward, so you could control the windlass and actually see how much chain is in/ out.

Chris

 

[alan006]

THanks for the info, John, seems a very sensible compromise.
Alan

 

[PeterGibbs]

Two quickies:

1. Although you will mount the windlass with a stout backing plate bedded in to spread the load, it will not take snub loads whilst at anchor. Have a bridle ready to take the load from the chain direct to a strongpoint - cleat etc - then you can sleep easy!

2. I marvel at the agressiveness of the corrosion encountered in this area of the boat. If the winch can be mounted under a cover, geat, or have one to place over it. Smother it in lanolin. Also the activation switch/es will need carefull siting if used, or use a demountable contoller, as I have, or the elements will soon reduce the whole shabang to a pile of soggy decomposites!

PWG

 

[kengill]

Use the biggest cable you can afford and always use a circuit breaker - not a fuse. They can get a bit expensive when the anchor is fouled and you have to get out the dinghy and row ashore and hitch a lift to an electrical supply house and buy three more fuses and take them back and they all blow....