Tanks and Containers

6th January 2023

On Sumara I need to carry three liquids in bulk – Water, Diesel and Paraffin. These are stored in fixed tanks which are supplemented with portable containers. Over the 32 years that I have owned Sumara I have learned a few lessons and picked up a few tricks. So here we go:

Water Fixed Tanks

I decided that the only space for fixed tanks would be under each saloon berth. This restricted the tanks size to only hold 17 L each. For coastal cruising on a boat with no shower this proves to be more than adequate (although many would disagree). On long offshore trips the capacity is increased with portable containers. I normally reckon 1.5 to 2 L per person per day is adequate for long sea journeys but Ian Nicholson’s Boat Data Book recommends slightly more at 2.25 L per person per day. The average person in the UK on land uses a staggering 142 L of water per day!

My consumption calculation assumes we are not carrying dehydrated foods and we have items such as tinned soups onboard. On ocean trips, we use sea water for washing ourselves and the dishes. Some sea water is also added to the cooking water where relevant, that saves having to add salt too! The small capacity of the fixed tanks results in them being frequently filled and flushed through so the water always tastes fresh. On a small boat, the main advantage advantage of having fixed tanks, over just having portable containers, is that they can be linked up to small hand pumps making dispensing water easy, especially in a rough seaway.

I made prototypes of my tanks in MDF to ensure a good snug fit and then sent them to (TBC) to be made in stainless steel. They were specialist tank manufacturers so I could be assured of reliable seam welding. I didn’t want deck fillers, so they are filled by bringing the hose down below. I specified a cross-over pipe between the tanks with cut off valves, but I’ve never opened the valves, preferring to let one tank run dry as a prior warning that I was beginning to run short. If a tank runs dry, it simply means using the other pump until the tanks can be filled again. Each tank has a large inspection hatch and a central baffle which seams to irradiate any sloshing noise. I was rather surprised to find water could get out of the breather pipes even though they were led right up to the deck head. Sumara does heel easily. I eventually fitted one-way valves to them. The tanks are held securely in place with 2″ polyester webbing wrapped under the stringers and fitted with Seasure buckles. I designed the tanks so there is a flat steel surface on top with an adequate clearance gap under the bunk boards so that I can store chilled food in Tupperware containers. It keeps the food surprisingly cold so long as the tanks have some water in them.

Picture showing the ugly but brilliant Whale sink pump and the lift out cooking pot sink

The pump in the heads is made by Whale and is as ugly as sin but the thing works a treat, and has done for thirty years.

Update July 2023: Sadly the pump is beginning to leak from the top and as they are no longer made I will replace it with the equally ugly Whale Flipper Pump).

I use a large cooking pot as a sink. It can be pulled out and used as a cooking pot when you catch a crab or need to feed hoards of people. It has two handles at the top so when it needs emptying, the pot is simply lifted out of its hole and the water is poured straight into the Baby Blake loo. Easy peasy, and without the need for an extra seacock.

The brass pumps in the galley have been a constant cause of aggravation. They all looked very nice but most would gush water out of the top or just completely seize up. It was normally necessary to pour olive oil into them to make them work at all. In spring 2022 I lashed out on a Fynspray lever pump. It was diabolically expensive but so far it has worked well. It does make a slightly disconcertingly cheap noise but that is apparently completely normal.

The super expensive Fynspray pump which seems to work well – so far at least

You may be thinking that sink shown above is mighty small and you may well be right. It was fine until I fitted the new pump and found I could no longer get the kettle under it! Maybe I’ll treat the boat to a slightly bigger sink – one day.

Update July 2023

I have now bought a new larger sink from Penguin Engineering which cost about £120.00

Update 8th January 2023

Roger Robinson has written to me to ask why I didn’t fit foot pumps. Well, it is a very good point. They are certainly easier to use when you are needing your hands to hang on to the boat. I was contemplating it but I couldn’t reconcile whether the 2D drawings would fit into the very awkward 3D space. If I could have borrowed a foot pump, I might well have fitted one. That said, I seem to manage with hand pumps, so long as they work well.

Water – Portable Containers

I do have a couple of standard 10 L “Jerry Can” type containers although I normally only carry one of them. They are rather bulky and remain that way even when they are empty. I carry most of my water in Ortlieb Water Bags

10 L Ortlieb Water Bag

The straps can be used to secure them to the boat’s stringers and they can also be squeezed into awkward spaces that wouldn’t hold rigid containers. If I am going ashore I will pop a couple of empty ones into my day sack in case I stumble upon a clean stream or available tap. On board the empty bags can be scurried away to free up space. They could also be blown up when they are empty to act as buoyancy bags. The blue ones would make useful swimming markers. They can even be used as pillows. My ones are black so they can be laid out in the sun for a luxurious hot water shower if there is any spare water. Ortlieb even sell a special shower attachment.

If you are sailing to the high latitudes where your source of water may be from ice or snow then there is a version with a roll up top, called a “Water Sack”. The wide top opening would allow ice to be collected.

10 L Ortlieb Water Sack

While on the subject of Ortlieb and water containers, I use the Ortlieb folding bowl for doing the dishes in the cockpit.

Ortlieb folding bowl for washing up in the cockpit – without waking the sleeping watch
with the clunking of enamel plates.

All the dishes are washed in seawater, except for the coffee cafetiere which is rinsed in fresh water. The mugs and tumblers are all colour coded so they don’t get washed at all!

Coloured coffee mugs with “matching” tumblers

Going slightly off track, but in our camper van we use a Decathlon water carrier with a tap on the bottom. We plonk it on a little folding table and find it very convenient. It might suit a small boat without fixed tanks. To save having to hold it right up to the tap, we have a 2ft length of hose fitted with a tap connector so the container can rest on the ground whilst it is filling up.

The Decathlon Water Carrier that we use in the camper van

As I have a slight penchant for fizzy water there are normally a few 1.5 L plastic bottles of mineral water kicking around. The bottles normally get refilled or they are occasionally repurposed as funnels and used for collecting diesel samples from the tank drain tap.

Diesel Fixed Tanks

My fixed diesel tank is made in stainless steel. I realise there is some debate about the best material for diesel tanks with many preferring mild steel, plastic or even monel, but my stainless steel tank hasn’t caused me any problems (yet!). I am led to understand that the stainless welds can corrode if the wrong welding rods are used. I suppose using a reputable tank builder would overcome this issue. I have no idea who built my tanks but I suspect Terry did. He built the boat, and I am confident he would have got it correct. Before installing fuel tanks should be pressure tested to 34,500 newtons/square metre to check for leaks. Sumara’s tank holds 14 gallons (63 L) giving a range of around 200 nm at 2,000 rpm using 1.25 L per hour. (driving my 16 hp Beta). Fuel consumption seems to be a black art with many conflicting graphs and data tables. This consumption was calculated by filling the tank to the brim and ruthlessly recording the engines hours set at 2,000 rpm then refilling and repeating. 63 L of diesel weighs about 53 kg (One litre diesel weighs 0.84 kg)

The tank is fitted with a sight tube, water drain-off tap, deck filler and breather. The tank is triangular in shape so there is a natural low sump point for any sludge or water to collect. The breather did get blocked once with a lump of varnish and it became impossible to bleed the fuel system until it was unblocked. It took a fair while to identify the problem. Apparently breather tubes should be twice the diameter of the fuel feed pipe.

The copper breather pipe on the aft of the cockpit combing which got blocked with a blob of varnish

The tank is below the engine level (mounted under the cockpit floor) so there is an electric fuel pump in the system. I carry a spare one just in case and indeed I needed to fit it in a hurry once. I treat my fuel with Marine 16 conditioner and have never had a problem with diesel bug – now I am really asking for trouble!

The Eberspacher heater draws fuel from the top of the tank. The feed rod stops well short of the bottom of the tank so the engine always has some fuel left.

Portable Diesel Containers

Scepter 20 L Fuel Can

You might think spending almost £100 on a fuel can is a bit lavish but these Canadian Scepter Military specification fuel cans are definitely the bees knees. Cheaper fuel cans are probably OK if they are kept upright in the shed or the back of a truck but if you need to strap down your containers flat to the coachroof, and expose them to full UV whilst being constantly washed with salt water, then you need something which is pretty butch. I’ve had an old container leak when the breather cap split and I can assure you it makes a hell of a mess.

These Scepter cans have very large openings so they will accept commercial filler hoses which can be handy in places like Iceland. The problem with the large opening is that it is pretty hard to pour the diesel out without it splashing over the top of my relatively small funnel. I did buy a syphon jigger device but gave up with it and bought a reducer cap from Scepter which works a treat.

19 mm Spout for the Scepter Can

The triple handles are handy. I find every year the diesel gets slightly heavier and carrying a 20 L container from a garage on the outskirts of a town is now quite a strain. A small folding trolley would solve that problem or just carrying the container between two people making use of the triple handle design makes light work of it.

I even had a Harbour Worker in Torshavn giving admiring glances to my beautiful varnished yacht. When I said “Hi” to him, he said “Lovely Diesel Cans!”.

Paraffin Fixed Tanks

I use paraffin to cook and for some cabin lighting. I don’t carry any gas onboard. One of the good things about paraffin is that it is possible to carry a whole seasons worth of fuel in a relatively small tank. Recent problems sourcing gas have made me feel just a little bit smug. The other good things about paraffin are that it is cheap, readily available, non-explosive and a great wood preservative.

The aluminium tank originally came with sight glasses even though I asked for a tube! The days of pink paraffin are over so sight glasses are next to useless. I eventually had it rather inelegantly altered.

Sumara has two fixed paraffin tanks. The first one is a storage tank which is made from 10 SWG stove enamelled aluminium and mounted against the deck head in the forepeak. It holds about 20 L. I have a small paraffin tap over the heads “sink” so that I can fill lamps etc by gravity. The tank now has a sight tube to replace the useless sight glasses. Due to its high position I have had to fit a valve onto the breather. The breather valve can be released on a port tack or in harbour but paraffin will gush out on a starboard tack. The tank has a flexible filler tube which I stick out of the forward air vent. I then screw a stainless steel funnel onto it to fill the tank. It is a palaver, but only needed once a season. The tank was made by “The Tank Company” in Poole and it cost a stonking £461.78 in 1994.

20 L going into the tank via the hose and funnel coming out of the vent

The other fixed tank is the Taylors Paraffin Cooker pressurised tank. I moved this from using up valuable space under the cooker, to a dead space in the heads. This was a good move, freeing up space for pots and pans. The new Hanse burners operate on a lower pressure than the old burners so the tank only occasionally needs a pump. The pressurised tank holds 6.8 L (1.5 Gallons) and strangely enough also costs the stonking sum of £455.00. Keep you eyes peeled at Boat Jumbles!

Paraffin Portable Containers

I have two good quality 5 L plastic jerry cans, one for extra paraffin (in the very unlikely case that we would run out) and the other one is for methylated spirits which I use for preheating the paraffin burners.


Sorry, if you were really interested in this type of tank

or even this type of container, although I do rent one of these for all my boat paraphernalia, and very useful it is too! Normal people buy a plastic storage box from B and Q, but boat people need 20 ft containers!

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