Capstan Connection & Fuses

[MrFish]

My electrical up grade is going ok, although abit slowly, and I'm confused on a few points. Your advise would be very helpful.
Should I connect the capstan (anchor winch) to the engine start battery or the House battery system? Why?
Do I need a fuse in the engine start cable to the starter motor? 37hp 3 cylinder diesel.
The fuse at the battery end of the cable should be sized to protect the cable running from the fuse to the starter motor, but how should the fuse or circiut breaker be sized for the capstan cable? Presumably to protect the motor from burning out? How do I figure out what that should be?
Thanks - this forum is a gold mine of info!
Ian

 

[Talbot]

Windlass needs heavy cold cranking amps - your engine start battery supplies these, whereas the domestic leisure battery system would be destroyed.
Suggest you have a look at http://www.yandina.com/Bank3.htm

 

[jerryat]

Re: Capstan Connection & Fuses

'Fraid I disagree with Talbot. Depends, to some extent, on the capacity/number of your service batteries, but by far the commonest connection is to these, and there is little or no risk of any damage.

The capacity of most boats' engine battery is comparatively low compared to their service set-up, and even if, as you should, you run your engine while using the windlass, you are more likely to drain the engine battery than the service batteries, particularly if you need to anchor several times.

Can't see why you need a fuse in the cable to your starter motor. Never seen this done. Or by starter motor do you mean the windlass motor?

If the latter, yes you do, and the circuit breaker (not fuse) needs to be sized to cope (just) with the maximum load listed for your windlass motor. Fit it in the positive cable as near to the battery connection as possible.

There are various tables available to help you decide on the correct size of cable to use for the overall length/amperage/voltage drop required, but I can't post them here at the moment. Someone else will be able to help I'm sure.

Don't forget when calculating the overall length to use in the tables, that this is the length to AND from the windlass i.e. the circuit!

Cheers Jerry

 

[Stemar]

Another option is to intall a relatively small car-type battery close to the windlass. That way you don't have the heavy cables needed to power the windlass running the length of the boat. You only need cables big enough to recharge the battery. It could be a much easier installation than running a pair of starter sized cables the length of the boat, but does put more weight in the bow.

In theory, the battery compartment should be vented to the outside. The ideal is to put the battery in an anchor/chain-proof box in the chain locker, but if it had to go under the V-berth, personally, I wouldn't lose a lot of sleep over it.

 

[jerryat]

Re: Capstan Connection & Fuses

Hi Stemar,

Trouble is, if you do fit the battery forward, unless it's got to have a big capacity, you STILL need big cables for carrying the load as the engine will (should) be running.

As you suggest, the weight in the bow is a significant factor, and IMHO is to be avoided at all costs. After all, it's much simpler to run a pair of cables forward, rather than install a substantial battery box there (think of heavy weather!) with all the associated protection of connections etc. Also means you have to go forward to click in the cicuit breaker each time.

Not worth the hassle for an inferior installation IMHO.

Cheers Jerry

 

[Evadne]

Re: Capstan Connection & Fuses

It's beginning to sound like pulling the anchor in by hand is actually the easier option! You could always fit a switch which disconnects the battery from the charger when the capstan is operated. If you've got that many batteries on the boat (starter, 1 or 2 hotel load and a dedicated capstan/bowthruster) then you may have fitted a multiple output charger that would allow you to limit the current to the forward battery, or even consider a 24V system to keep the currents down. Just remember, though, that the chances of something going wrong is directly proportional to the number of components and connectors in the system.

 

[Stemar]

Re: Capstan Connection & Fuses

I often sail on to and off anchorages. IMHO, the point of the separate battery is that you don't need the engine running as you would if the windlass is wired to the start battery.

If the "charging current" when using the windlass with the engine running is a concern, a relay that disconnects the charging circuit when the windlass is in use would soon solve the problem. In fact, without doing the sums, I suspect the current would be limited by the voltage drop on thinner wire and the buffering effect of the battery, so it wouldn't matter.

I'm not suggesting that "my way", for which I claim no originality, is the only, or even the best way to do it, just an alternative which may suit some boats. For me it would be easier to build a suitable battery box forward and run twin 2mm cable for charging than run a pair of 10mm or more cables.

The battery doesn't have to be huge - dropping the hook and raising it again - say 2 minutes use would give change from 4amp hours even with a 1200w windlass, so I reckon a 20AH battery would do as long as it can deliver the current.

 

[paulrossall]

Re: Capstan Connection & Fuses

I have 2 110amhr (or whatever the correct term is) domestic and 1 75amhr starter bettery. I always have the engine running when picking up the anchor and have it charging the domestic batteries which supply the windlas. It is an old Simpson Lawence windlas and I have a 75amp circuit breaker supplying the big cables that run up my shallow centre bilge to the windlas.
I would not fit a fuse/circuit breaker on the engine start supply. They don't fit them on cars do they?

 

[Talbot]

Re: Capstan Connection & Fuses

[ QUOTE ]
'Fraid I disagree with Talbot. Depends, to some extent, on the capacity/number of your service batteries, but by far the commonest connection is to these, and there is little or no risk of any damage.

[/ QUOTE ]

Thats your priveledge to disagree, however they are also your batteries so you can shorten their lives if you like I dont mind /forums/images/graemlins/wink.gif

Personally, I prefer a single battery up forward for this purpose anyway, and that battery needs to be one that is designed for delivery of reasonable cold cranking amps. The link I posted earlier gives a good set-up.

 

[DaveS]

Re: Capstan Connection & Fuses

I would largely agree with this. I use a separate battery (in my case near the mast rather than very far forward - but that was more dictated by practicalities of where I had room) with few problems. It's charged from the Domestic bank via a Shottky diode. It's worth adding that if the engine is on while operating the windlass, it is likely to be at or near tick-over and not supplying much current.

I did get caught out, however, when I discovered that if I did rev the engine to relieve the strain on the chain while lifting the anchor this could result in one of the windlass battery charging fuses blowing. I therefore uprated the charging circuit to 6 mm2 with 15A breakers at each end and it is now trouble free.

 

[jerryat]

Re: Capstan Connection & Fuses

Hi Dave,

"""I did get caught out, however, when I discovered that if I did rev the engine to relieve the strain on the chain while lifting the anchor this could result in one of the windlass battery charging fuses blowing. I therefore uprated the charging circuit to 6 mm2 with 15A breakers at each end and it is now trouble free."""

Yes, this is part of the problem. Many boats, mine included, have an alternator controller (Adverc e.g.) where, even on very low revs, there is a substantial output going to the batteries. Bet even your 6mm gets pretty warm too after trying anchor a couple of times on the trot! /forums/images/graemlins/wink.gif

As I mentioned earlier, on my little boat, which is heavily laden when we're living aboard, I don't want the relatively huge additional weight in the bows. I've already got enough up there with all the anchoring systems, spare inflatable etc!! /forums/images/graemlins/crazy.gif

My set-up, with the windlass connected to the service bank (330 amps) has been in operation now for 11 years (including seven full time cruising and hundreds of anchorings) and they are the original batteries. They still hold 12.7 - 12.9 volts too.

I am therefore totally relaxed that their lives have not been reduced!!! /forums/images/graemlins/smile.gif /forums/images/graemlins/smile.gif

Happily as always, everyone to their own.

Cheers Jerry

 

[DaveS]

Re: Capstan Connection & Fuses

Thanks for the point about the smart alternator controller - one of the jobs I was considering for this winter was to fit one. I have to admit that I hadn't spotted the implication for the windlass battery charging circuit. I think the easiest and cheapest solution will be to put a normally closed relay into the charging circuit with its coil driven from the windless circuit breaker. With that in place the original lighter duty charging circuit would have done - but I won't be re-re-wiring it!