Heating is important to be  able to prolong the season here in Norway. I just wished I had installed it before the boat was sailed from Denmark to Norway in November, arriving in Oslo at 03:00 at night in northern gale (headwind) and on top of that it was snowing!

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I chose a 5.5KW's Webasto  heater - that according to the specs should be enough for around the year sailing in Svalbard (Spitsbergen)!

The heater is mounted on the backside of the bulkhead of the aft SB cabin. It's mounted in a 45? angel, that makes routing of the ducts and exhaust tube easier. The hot air outlet is pointing down towards the channel in the middle of the boat, going between the two aft cabins and leading to the engine, and this is the duct that the hat air duct is following.

The hot air duct is split in to 2 thinner ducts just behind the engine.

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One duct continues on SB and the other goes thought the bulkhead to the port aft cabin, along the water heater, under the small bench, where is splits up, one to a vent in the cabin and the other through the bulkhead into the aft head compartment. This means that half of the heat can go into the aft head compartment, which also doubles as drying locker.

On the starboard side there are 5 outlets, one in the aft cabin, 2 in main cabin and one each in the forward head and the f'castle.

All the vents can be adjusted, (open/closed and rotated), except the one in the main cabin, which must always be open, or else the heater will overheat and shut down.

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The heater control is integrated in the instrument panel.

Notice the small switch to the left of the temperature control, this selects heating or ventilation.

wiring diagram

Have a look at the wiring diagram below; the supply for the heater is connected directly to the battery (via a fuse), not via the main switch. A relay is used to ensure that the heater is turned off when the mains are disconnected, but the heater will still have power to do a controlled run-down, in order to cool-down and prevent soothing of the burner.

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click on the diagram for a better resolution

holding tank

The holding tank is mounted aft in the starboard side.

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The tank is held in place by 2 screws, and is also laying against a wooden block on the lowest point. In addition to this rudimentary fastening, I used expanding Poly Urethane foam.

An overrun/breathing hose is lead through the hull.

The drainage is through a whole in hull just above the waterline, where a ball valve is fitted. Behind the valve is a electrical bellow pump. The alternative to this was a grinding pump (a   macerator), but this type of pump clogs up very easily!

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Behind the pump is three-way valve, that is operated from the platform aft, and makes it possible to either use the bellow pump or a suction hose ( the black plug to the right of the shower) to empty the tank.

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The access from the platform makes it easy to fill the tank with fresh water for cleaning etc.

Only the aft head is connected to the holding tank, because I want to reduce the length of the hose and also the risk of leakage, and leakage from a holding tank is literally shit!


Under the sink in the aft head, another three-way valve is mounted so it is possible to choose between the holding tank or straight out to the sea.

extra holding tank

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The main holding tank holds 65L and serves the toilet aft, the toilet in the forecastle would be used during night, but without a holding tank in a nice natural harbour - No!

A mould made of cardboard was used to verify that the 12L tank could be fitted before it was ordered at  Watski.


The tank is fitted above the waterline and is using gravity to empty itself. The supply tube is fitted with a gooseneck and an overrun/breathing hose is lead through the hull just below the railing.

The drain hose is using existing fittings, and since no new valves where fitted, the tank is in permanent operation.

The tank is held in place by expanding Poly Urethane foam.


hot water meter

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How much hot water is left? Good question!

For how long was the engine running?

When was that?

How much hot water is used?

Well, my Oracle is a small digital thermometer from Clas Ohlson, mounted in the secret compartment in the port aft cabin. The picture is taken during the winter and the empty water heater has a temperature of  2°C.

The placement was chosen because the cable for the sensor was only 3 m, and the cable cannot be extended without recalibration.