The story of Mojo and the Magic Reserve Diesel Tank

Mon 3 May 2021 12:17
30:11N 20:51W
Two reefs as the forecast early morning 8 knots turned up as 19knots. Target destination is SE at 103 degrees but at the moment I'm pointing sideways at 42degrees cos the wind is still to sort itself out and turn to come from the North, and let me go across it to the south east. Zipping along at up to 8 knots though, wind sometimes up to 20knots and sometimes down to 12 knots.

Mojo was in Lanzarote last year but the covid lockdownery meant that many others weren't there at all. This badly affected all the tourism things of course .... but it did mean that all the boatfixing types were relatively free to work on Mojo.

Ace boat engineer Wes runs the Catlanza team. Catlanza is a series of day-trip catamarans that sail out of Marina Puerto Calero every day and back, very good fun, apparently the most popular tourist excursion on Lanzarote. In a normal season there can be several boats in operation, and there's a fair bit of organising to make it all happen - coaches to pick up the customers and drop them back again afterwards, and perhaps toughest of all is to keep the boats running all day every day. Hence it's very handy that Wes is boat engineer type with lathes, welding gear, machine tools all that.

So anyway, with a quieter summer, I suggested to Wes that he do a Big Refit on Mojo? And he said Yes Okay. There wasn't much more of a contract than that, really. And of course there can't be, because so much of the work seems easy and then is awkward, getting parts etc ... while some other stuff might seem really difficult but then be easy.

One thing I specially wanted Wes to sort out was extra fuel tanks. These Fontaine-Pajot Eleuthera boats could be fitted (at original build time) with 1200litre tanks (under the cockpit floor) instead of standard as-Mojo 600litre tank (fine for coastal crusing) but once built there's no access to retrofit bigger tanks under there, darnit. But there's loadsa space in the engine room, how about that Wes? Hmm, Wes doesn't like it - with tanks in there the boat could NEVER get approval as a commercial charter boat, and it's not a great idea kinda warming the fuel actually inside the engine rooms is it? Not really. Wes finds space for two add-in tanks at the back of the bridgedeck, much better.

By mid-october last year these were ready, two specially-made alloy tanks, joined together, mounted all properly, cushioned and strapped down internally and a deck filler, plus a little pump to move fuel from these isolated tanks to the main tank from which the engines draw the
fuel they need. Perfect. How big are the tanks? Wes reckons 500-600 litres. Very good.

Of course, I don't really need this much fuel for crossing the Atlantic, not really. It's just lazy or impatient of me, or a bit of both. Lots of people cross in sailing boats and never use the engine at all. But they usually take a fair bit longer than the 16days so far it has taken to get with 400miles of Lanzarote from St Martin. But for anywhere outside the Atlantic - Pacific for example, I definitely will need to be able to carry more fuel. The more the merrier, really.

On the outbound trip in November with the Adventure Girls (one of whom Jess has gone and bought herself a ferro-cement boat PENELOPE in the Pacific, three others are somewhere S America) I took full tanks (1100litres?) and some jerrycans too. But I never used the reserve tank at all, and the fuel taken in Gran Canaria was all still in there in St Martin before leaving : with big solar panels, Mojo almost never needs to run engines to charge the batteries.

So on this transat trip, I filled the jerrycans and used those to refil the day tank. Maybe that wasn't the best idea - cos i still didn't really know the capacity of the reserve tank, nor (really) the main/day tank - it says "600litres" but I have no idea how much of that 600litres I can use - how high is the pump in the tank? And 600litres sounds a bit rounded, hm? It would be a lot more believable to read it as "594 litres" or "613", I think.

So anyway I ran the pump to transfer the fuel, and all fine. The pump is rated at 3litres a minute. I ran it for 60 mins. There's a timer so I don't forget about it like that time with a previous boat i ran the tank and transferred a load of fuel from one tank into er, the marina, ahem. Then again 40 mins and then 33 minutes and that makes 400litres. Then I ran it another 33minutes making 500 litres, plus a bit more and the guage seemed to level off.

Then I had a think, and using a PELA vacuum pump I hand-pumped the tank to get the dregs out, and I got a whole 6 litres into the pump. Fair enough really, big tanks. So i handpumped again and got another 6 litres. I think I handpumped another 8 times and got 60 litres. Very Hm.

Now I'm running the electric transfer pump again, and I can hear it fuel going in, it seems. The pipe "beats" which i think it would only do if pumping fuel. There's a lot more than any 500 litres in that tank. Maybe it's a Magic Tank, that just supplies diesel for as long as you like? Growing up with two older sisters meant that there always a ton of fairy story books around the house, and I read them all in great detail - very useful for expanding the imagination and understanding the human condition, but no need to go there.

Anyway, I'm pretty sure that there's no such thing as a Magic Reserve Diesel Tank, except in yet-to-be written and probably-never-to-be written Blokey Fairy Story. Meanwhile the pump is still going and the tube still beating as though it's pumping fuel. Yes, just like that never-ending salt mill that makes the sea salty.

I kinda need a way to calibrate the tanks. I think I need to fill them, and then progressively empty the main tank into jerrycans - and as soon as the engine stops I'll know the true capacity of that tank. Same with the reserve tank really. One of the more boring boat projects there I must say, but harmless I suppose, aside from splashing diesel around the place. Mainly, though, I should hold back the jerrycans - that way I know exactly what I have as "spare" - as soon as it's in a big tank, I don't really know anything, not exactly.

The pump is still running and the pipe still pulsating. The reserve tank gauge is up to 3/4 and that moves as though there's a float in there.

And so, dear reader, the never-emptying Magic Diesel Reserve Tank is the reason why boats always smell a bit dieselly. Or whatever, some other unlikely conclusion, work it out yourself okay? And they all lived happily every after. Oh yes they bloody well did! Fairy story innit so I don't have to "tie up loose ends" see? Not yet anyway.