Diesel - How much to carry

[StevenJMorgan]

My boat has a relatively small (100l) diesel tank. Other boats that I have looked at of similar design and length (37 ft) seem to have between 300 and 450 litre diesel tanks.

Given that I am slowly preparing for some extended cruising I feel that I should increase my range and therefore tankage. My Volvo 2030 seems to use 2 litres an hour max which with the current tankage gives me a range of approx 300 nm which I feel is not enough.

So how much would one consider a reasonable amount of diesel to carry on board for extended cruising possibly in some unaccessible parts of the world and potentially a red sea passage. Space is not an issue - current tank is in the port quarter with loads of extra space available - but I am concerned about the extra weight.

So assuming I need to increase capacity should this be done with 1 new large tank or should I retain the existing tank and add an additional ?? If the way forward is to add an additional tank should this be conneced live to the current tank or should the new tank be a holding tank which then can be used to fill the existing tank? - All questions I'm afraid.

Any views appreciated.

 

[cliff]

Have you considered using your sails to increase your cruising range?

Personally, I find them wonderful things and they really do save on the diesel.

Joking aside, I carry 100l diesel in the main tank and about another 50l or so in jerry cans which more than covers my needs.
If I was planning to do the Red Sea I would be more concerned with storage of "passage tokens" (cartons of Marlboro cigarettes) for the Suez canal unless you plan to go the long way round.
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"Artificial intelligence is no match for natural stupidity"

 

[ChrisE]

Interestingly, we have a similar sized boat, tankage and fuel consumption and we went AWOL for a year thought about this a bit.

The answer, I think, comes down to your sailing philosophy. On longer passages, say 4 day plus, we start getting bored when the boat speed falls below about 4 knots and usually have the engine on if it drops to 3 knots for any length of time.

In addition to the 135l in the tank we carried an additional 150l in 6 25l jerries. This gave us a motoring range of about 150 hours which is the best part of a week or 900 miles of steady motoring probably nearer 1200 miles of motor sailing in light winds with lower revs. We've thought of upping our tankage and decided to stick with jerries that are more convenient for fillling up when you are miles from the nearest marine diesel pump and have to collect fuel from garages.

In the event we only really got near to draining the tanks on two occasions once when we foolishly sailed into the Azores high in an effort to get to the Azores and ened up motoring for a day and a half to reach some wind and later when our forestay snapped miles from nowhere.

 

[mike_bryon]

We use our sails but carry around two and a half thousand litres of fuel! It like money in the bank. On previous smaller boats we always carried an extra 100 or so litres in cans.

There is more than cruising range to consider. Will you charge batteries by daily engine running is another consideration. It’s also about independence from unsure quality of supply and availability and whether or not you can arrive somewhere any time or need to use the engine in light airs to keep to commitments like crew changes, visits from friends and family and so on. We converted a water tank to fuel on a previous boat and fitted a water maker so that we could extend our cursing time between water refills.

On our current boat we fill with diesel once a year (we burn diesel for heating) and shop around for the best rate.

Best wishes with the plans.

 

[TigaWave]

As others have said, big plastic cans are the answer....but a useful point is to work out an easy clean and water tight way to get fuel from the can to the tank even in roughish weather. I've been on a boat where this hadn't been considered, fuel filler on sloping transom and trying to pour fuel into a funnel with short pipe, spilling quite a bit and getting water in the tank at the same time.

We set up a screw top that had two pipe holes sealed, one went to old avon foot pump the other from the bottom of the can to the tank filler, a few pumps and the syphon had started. We didn't even have to untie the cans from the rail to re-fill. The filler pipe was a very good fit on the tank filler hole so even with quite a bit of water around hardly any could get into the tank.

If you're motoring because you've lost your rig it could be rough and wet and the last thing you want then is water in your fuel.

 

[Amphitrite]

Why not go for a second diesel tank? This will be a lot less hassle than jerry cans (however, some will be needed for refilling at remote places) and you will not have the problem of stowing the cans (smelly inside the locker, danger of loosing them overboard when stowing along the rail). Additionally, it will give you a backup tank if you somewhere got dirty diesel/water in the first tank etc....

 

[claudio]

Machine Mart sells fuel transfer pump to make this job easier see Here

 

[bazobeleza]

Belt and braces is my policy, I have about 1500l in two tanks and am considering fitting a third, each tank with its own filter so if youre in rough seas and the crud in the bottom of the tank gets churned up (as it it did with me) I just swap tanks a by means of of a couple of taps and continue, last thing you need to be doing at the end of a passage is wallowing about near the shore in rough weather changing filters and bleeding the engine.

My advice is to keep your existing tank put in another with its own filter and increase your range, by the way your method of calculating range is suspect, if your tank has 100l you've probably only got 50/60l usable, rough seas slosh it around and you end up sucking air/crud and your 2l/hr will probably double against wind and/or tide, so you may have as little as 75-120 nM range dependent on conditions. hope this helps.

 

[StevenJMorgan]

Chaps - thanks for the comments.

I guess what I'm really looking for is thoughts on how much one should really carry. Yes I like to sail where I can but depending on time constraints and location would consider motoring if boat speed fell below 3 knts.

I don't like filling up with jerry cans because its messy, water can get in when filling up and when they are tied to the rail, and you have a lot of weight on deck.

I suppose inadvertantly I have answered my own question and the answer is to increase tankage but to how much? Should I rip out the existing tank and start again or just add another ??? I'm thinking that if I added another tank this could be isolated from the main tank and kept empty when coastal cruising and filled when planning a long cruise - the new tank could be linked to the existing with a pipe and a seacock and used to 'refill' the main tank - would this work - assuming new tank above main tank??

 

[bazobeleza]

Transfer pumps are expensive about £90-£120 and the best way to link them is with a dip from the top of the tank that does go to the bottom of the tank therefore no crud gets transfered (hopefully) though this is less of a problem with plastic tanks that don't rust, but remember most storage tanks in marinas are big rusty old steel things with god knows what inside them. I filled one tank with 700l in a marina and it came out as 680l diesel and 20l water and a large amount of crud. I was not a happy bunny! three large buckets of water in your tank is no joke.

If you transfer fuel make sure that it passes through a filter. then if a tank gets contaminated at least you can use most of the diesel in it.

Another good idea was a Day Tank a clear PU tank of about 20l in PBO some months back. above the engine and fuel transfered into it from the main tanks enough for the days sailing.

 

[jerryat]

Yep, we're similar to you Chris, but have only circa 90 litres in the fixed tank. We find that, with our small engine, a further 6 X 25 litre plastic cans gives us plenty of range.

We only carry this number of cans on the longer distance passages though and reduce them to two or three if the passages are only 3-5 days.

Re the other posts, transfer is simple. We use those horrendously expensive (circa £1.50 each!!!) plastic syphon thingys, where one leg goes into the can, the other into the tank, and you squeeze the bulb at the top 'till the stuff flows. Absolutely no mess and no waste.

We have topped up our tanks lots of times in lumpy weather using this method with no problem. Mind you, our diesel filler is in the cockpit under the teak gratings, so it's alway a safe, easy job.

 

[ChrisE]

Jerry, you beat me to it. We used a syphon and a little battery driven pump that must have cost all of £10.

I should have added that we used to keep the cans on deck, now we keep them securely tied below decks. We found that keeping them on deck meant that the plastic cans degraded in the sun and were worried about losing the cans and the gaurdrail in heavy seas.

 

[davidbains]

I would have thought that 100litres plus some cans is enough
unless you're going to cruise the Pacific for a year.
I have a 12 gallon tank and two 5gallon cans and I have never run
out of fuel. All the extra weight is just slowing down your sailing speeds
especially light air performance. Do you have a lightweight "multi purpose
genoa". In hot summers we carry much more water than diesel.
Where are you planning to cruise?

 

[snowleopard]

The best fuel transfer device I have seen is a 3/4" plastic tube with a ball valve in one end. You put the valve end into the can and jiggle it up and down half a dozen times which fills the pipe and starts the syphon. The large size of the pipe means I can transfer the contents of a 35 litre can in under 5 minutes.

I bought it at a boat jumble for around a fiver.

 

[hlb]

I had the same problem. Though I suppose I burn more than you. I looked at s/hand truck tanks, but the fittings were all the wrong size. In the end I decided on the quick easy, cheap solution. 45 gallon oil drum mounted in a cradle and strapped down. Standard BSP fittings and an inline pump. Wish I'd done it years ago, means I fill up where I want to, rather than having to. Might even fit another one!!