Hi all

I think its about time I rewired my boat, It"s currently a horrible mess.

At the moment there are two house batteries and one starter battery.

On the supply side there is a wind generator and a prop generator and of course an engine alternator. I am going to add an Electric Windlass and Bow Thruster to the boat.

I will also be adding some solar panels.

Im thinking that I should keep the starter battery for just that, starting. Im just trying to get my head around the idea of say adding another house battery to compensate for the extra equipment (Windlass and Bow Thruster) or locate them in the fore cabin on their own bank.

Any advice would be gratefully received. As would a wiring diagram :)

Thanks

Chris,
One of the issues about bow thrusters and a windlass is you need a lot of amps at the bow which means chunky, heavy cable runs. One of our friends got around this by putting a dedicated battery in the fore peak fed by a 240 volt charger with slim cables. Obviously you would need an invertor or invertor/charger near your main house battery bank but this may be an upgrade you are already considering. It 's a neat way of powering a bow thruster.
Simon

Thanks Simon.

I am leaning that way myself, as the actress said to the bishop.

ChrisJ (and Simon),

I have no experience with wiring a bowthruster and/or windlass. What I do recall is that both take so much energy that you either have a very large, expensive, heavy battery pack up front or need to run your main engine while using them in order not to deplete the bow battery pack. Using a 240v link in beween does not change that.

Therefore, if you use the 240v approach (which sounds logical to me), you still need to take into account the energy usage of the invertor that provides the 240v power. If, say, the windlass / bowthruster uses 1000W, this will use ~80Amps from the battery pack. Therefore (taking into account the losses of converting 12v -> 240v -> 12v) you need maybe 100Amps at the primary batteries if you want to provide the whole power intake, or at least 50 Amps if you want to power half of the power intake from your 240v system.
That said, it seems to me that you need to check whether your alternator and main battery pack are currently up to that depletion for short periods of time. If so, no problem, if not than you need to upsize either main battery pack, alternator or both!

ERIK
I think you misunderstand. The 240 volt system just charges the battery so the current use will be minimal and depends on the size of the charger. The battery in the fore peak provides the 80 amps plus and is then recharged in the same way that you might want to use a trickle charger to maintain the the charge in an engine starting battery.
Simon

Hi Simon,

Clear. That would definitely work with a small charger.
You would need to look very carefully at the size of the front battery pack, as 80+ Amps is a lot of current to provide with a battery!

Regards
Erik

Thanks for all your help with this.
I 'm doing lots of homework on this now and the fog is slowly lifting.

Chris

An alternative some boats with bow thruster have is to use 24V. This way the cables running forward can be somewhat thinner.

Would a 24V circuit just for the bow thruster work? This probably would add some unexpected complexities. But perhaps these can be worked out.

Thanks Hasbun
I would say that the proposed 24v system would only be used for the bow thruster or the anchor windlass. I can 't see them both being used at the same time.
I 'm guessing an isolated system would be OK running at 24v, I 'll need to check that though.