Das Boot – the power sources

Frankly, haven’t the time to draw the hull layout – this is an old layout but thereabouts- there are five beams altogether, two at each end, up high.

Purpose of this diagram is to show issues re batteries/other power.

Power supply, apart from sail, is via DC [solar trickled], AC and gas.

With DC, length of wiring is an issue in a long hull, plus hull to hull connections, so there are three batteries – at A, the central pod, at B, the galley, and at C the wet area. All areas are above sea level by a foot. On the canal, the A battery stores in the stbd wet area [locker] or can be used in tandem with either of the other batteries or used in rotation with the other two – many possibilities there.

Largest power consumers are watermakers, pumps, ovens, none of which I’m connecting to power, nor microwave.  Example is the bilge pump.  I’m using a lever pump in each cabin such as this:

… which sends outflow overboard between hulls in the wet/hatch area.  These are coupled with handheld which I already have – one for each cabin, ditto with fire extinguisher [2kg], blanket and hatchet per cabin.

For the amidships raised area of each hull, below the sole, are the waterbottles [100 by 10 litres – already have], so any water ingress below that competes with water already there.  Any overflow onto sole runs off overboard [self draining].

At this point, a reminder that each compartment is sealed by a wall, no egress or entry from other compartments – need to go up through hatches and down others.

At sea, a 35 days maximum trip [the longest I’ll ever do per leg] allows 28 litres a day of fresh water to be used – three crew plus final washes counting as one person = 7 litres a day pp – plus 50 litres per person allowance of personal drinks brought on board and stored in cabin hatch areas.  As the amount of water shipped at the start does not alter = 1000 litres or 1 tonne, then fewer days at sea obviously increases the allowance.

Some examples – 28 days takes me direct to Cape Town, same to the US via the circuitous Bahamas, about 28 days Cape Town to Fremantle because though it can be done faster, it’s better at wave speed – less sail used, rode trailed. No voyages go anything but downwind, hence the square sail as the power sail.

There is a pump action watermaker for slow-refill of containers – some each day with extension handle.

Can only be used at sea, not in rivers – too dirty, also it’s just a desalinator.  I’d expect in a river to be able to use a kind host’s domestic water [pay for it of course].

I use mechanical afap over electric – bare minimum use of DC – nav lights, houselights, radio, some appliances via inverter, e.g. I do have a travel iron and steamer for use when closing in on port.

There’s the 3000w [peak] generator and 15 hp outboard, both with AC outlets.

On that basis, 180Ah by 3 batteries is a bit of overkill, especially with the solar panels – Aldi currently sell 6w output tricklers on special by the way.

The solar panels go on the oblique sides of pods – I count the cabin roofs as pods too, although the solars only go on the inner side there, close to the battery, plus they tilt in all locations.

I aim for around 15w real output from the solars on any one battery, meaning far less than rated output of course.

House lights – being a strange man, I’m not into night lights – daytime is long enough for reading, night is for sleeping and one other thing.

However, houselights are used amidships in the convivial area of each hull and in the steering pod.

The two aft cabins use electrically inflated airbeds pictured below, the cream coloured background in the pic is memory foam bed and these go on for’ard berths over slats.

The generator sits on the cabin roof downwind of the hatch, the power lead goes through hatch and into cabin to electric motor on bed. It’s an occasional job.

2 comments for “Das Boot – the power sources

  1. ivan
    April 15, 2019 at 18:04

    Don’t forget that you will need water to clean the salt off the solar panels which should be marine quality unless you want to throw them out after a couple of months. Salt deposits from salt water spray can reduce the output of panels by up to 80%.

    Another thing, you should have a way to charge all the batteries in parallel from the full set of panels, use diodes to prevent batteries with high charge from charging flatter ones.

  2. April 15, 2019 at 18:18

    Hi James,
    I have been looking at alternatives to diesel power for a sea-going boat research project,using a combination of storage batteries and ammonia powered fuel cell. One of the hardest aspects to get a handle on is the “hotel loads” of the boat (as opposed to the energy required to move the boat at various speeds/distances).

    Do you have any views on what the typical overall electrical energy use would be per day in terms of kWh on one of your longer trips both at sea and when moored? I’m generally thinking lighting, cooking, pumps and other systems. I can appreciate that you prefer to keep a lot of stuff manual to avoid having to rely on power but it would be helpful to get some sort of steer on the level needed.

    Kind regards
    Jon Davies

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