Sumara of Weymouth

17th March 2025

Reading Time: Ten Minutes

When my boat was based primarily on the south coast of England, and, given that my sailing was mainly over the summer, the need for heating was very low down the priority list.

On the rare occasions that I was sailing in the winter, my survival method was to wrap up warm and throw a couple of potatoes into the Taylors paraffin oven. I would also leave one of the burners on the top of the stove burning on a very low setting with a cast iron plate over the top. The kettle just needed sliding across to provide a hot drink and eating the baked potatoes would warm you up from the inside out. It kind of worked, but cold feet were always an issue.

I installed a Taylors diesel heater on my previous boat, Jose of Dover, but she was 28 foot long and I managed to find the space. It was a drip fed heater, but if you accidently got the drip rate a bit too high then, unbeknown to those below, black smoke would belch out of the chimney. That was not popular with the neighbours.

It was only when I decided to sail Sumara to Spitsbergen in 2002 that I seriously researched installing some proper heating. All the pilot books insisted it was essential, although they also said a sat phone and radar were crucial too, facts which I ignored. Actually sailing in the Arctic summer is very similar to sailing in the English winter, so you could argue that heating isn’t essential. A malfunctioning heating system certainly wouldn’t stop me sailing north. The thing is that if you are properly dressed in merino thermals and thick woolen jumpers you can tolerate the cold. The problem is not so much the heat, it is the dampness. Arctic weather can be relentlessly foggy or even hi to the q to drizzly. What is really needed is not a heater, but a drier. Putting on wet clothes to start your watch will quickly sap the morale out of any crew. If your oilies are dry and warm, then you can at least try start your watch with a smile on your face.

There is nothing I would have liked more than a little solid fuel stove. The atmosphere below would be truly wonderful. That smell of burning wood or charcoal wafting in the air and the gentle glow of smouldering logs. Sadly logs are not very available in the Arctic and salt impregnated driftwood doesn’t burn very well. The radiated heat that is so appreciated by the British, but not by all. I say that because British houses are often so badly draft-proofed that we are quite used to sitting in front of a blazing fire with a scorched face while the curtains waft icy air through the single glazed sash windows to chill our necks. This is something most Scandinavians find intolerable!

But there was a problem. Sumara’s small cabin hadn’t got the space for a solid fuel burning stove without major surgery to the lovely woodwork. The other problem was that a solid stove isn’t really ideal for drying oilies. What I really needed was a diesel heater that blows out warm drying air.

In 2002 that quite quickly led me to either an Eberspacher Airtronic diesel heater with two outlets (Eberspacher D2) or the Webasto equivalent. I choose the Eberspacher, can’t remember why.

Before I bought my heater I would wander around the harbours in the winter and have a chat with boat owners who had one fitted. The boats are easy to spot by the familiar (irritating?) roaring noise coming from the exhaust. The best tip I picked up was:

“Put the heater controller somewhere in reach of your berth. That way you can fire up the heater before getting out of bed. Good advice!”

As you can see I put the controller on the bulkhead in front of my berth. I mounted one outlet in the main cabin pointing, quite coincidently, towards my berth and the other in the heads pointing at the oil skins.

That makes it sound easy, but in a small boat it was a nightmare task to fit. The heater had to be mounted transversely in the “lazarette” but access was restricted to a small round hatch in the cockpit bulkhead and through the back of a locker. Everything had to be done blind. Camera phones were very rare in 2002!

A search in 2025 would lead to various Chinese and Latvian-built heaters. Some of the Chinese heaters are so cheap that you could buy a few spare ones for the price of a German made Eberspacher. The Planar heater sits neatly between the two and would be a tempting choice had it been readily available at the time.

My Eberspacher worked pretty faultlessly until 2022, so twenty years of service isn’t too bad. Eventually it became troublesome and I thought the fault was the controller so I had one sent out to the Faroes where I was moored. The heater did then fire up, but not straight away, there was something else wrong. So last year I was confronted with a choice – repair or replace. I needed something to work as I will be heading towards Scoresby Sund in 2026.

Everyone was screaming at me to just buy a Chinaspacher, but I couldn’t quite bring myself to do it. The Latvian heaters looked good, but in the end I decided to tear out the Eberspacher and send it off for an inspection and opinion. They reported back that the heater needed a couple of sensors but was in very good condition with only a few hundred running hours, I decided to stick with it. I also decided to buy new ducting (it is very fragile), a new wiring loom and a new diesel pump. The old pump may have still been working but it was rusty and I just wanted everything to function perfectly. The costs soon added up to £535.00. I still needed to buy decent worm drive clips and a proper waterproof plug and that added an £100.

There are a few irritating things about the Eberspacher. When you are paying three or four times the cost of a Chinese version you really expect everything to be top notch but some things slightly let it down.

1. I would never use a BZP Jubilee clip on Sumara so it is a frustration that I had to saw off all the rusted clips on all of the ducting. That probably took three hours work. I do think that they should have been stainless.
2. The wiring loom isn’t tinned wire, yet it is a marine version of the heater. Surely it wouldn’t cost too much to upgrade that.
3. The new diesel pump came without a waterproof plug. The supplier said I could use spade terminals but that is not the case. It does need a waterproof plug. Luckily I salvaged my old one but to run that pump with open terminals would have been pretty dangerous.
4. The wiring diagram is in German. A yellow wire is coded GE – pretty confusing. It took a while to work out what was going on. Couldn’t they take the trouble to change the diagram, is the English speaking market really too small?
5. I was supplied with an insanely fiddly non-waterproof plug to connect the seven wires to the controller. I managed to buy a decent waterproof plug from RS Components. Plug and play with waterproof connectors would have been good.
6. The coach screw supplied to fix the pump to the bulkhead was BZP and rusted. How much more would a stainless steel fixing cost?

These are all little things but when you are paying for a premium product you shouldn’t really need to go buying your own clips and plugs.

Rant over. Next year I am heading towards Scoresby Sund so I hope the thing pumps out some warm air to keep us dry and cosy up there. I will report back!

An Alternative system

On Will Stirling’s boat “Integrity” he had installed a clever system to dry the wet weather gear. It only worked while the engine was running, but in the Arctic regions it is common to have little wind for extended periods. It involved piping water from the engine cooling system through a “car” radiator with a fan beneath it. Once the engine had warmed up it would deliver enough hot air to dry all the wet gear and keep the cabin warm. The electrical draw was of no consequence as the engine would be running. At anchor we used a coal stove (shown above).