Make sure your fuel tanks are clean ...

[Delfin]

Originally Posted by Dockhead

From once in 20 years to once in 2 days, depending on the fuel, the weather, etc.


In short, it's not possible to make a rule of thumb. I used to have my tank cleaned professionally every two years (at a cost of almost £1000 a pop), as I'm paranoid about fuel, having previously cruised in diesel-bug ridden Florida, but eventually realized that since the tank was always squeaky clean, never a speck nor a drop, it's not necessary in my particular conditions.



I would say you should have a good look inside your tanks no less often than once a year, and clean them if you ever see any visible dirt or water, but continuously keep a sharp eye on your filters (use dual Racors with the glass bowls), and if you see the slightest change in anything, pop the tank and inspect it.



Avoiding biodiesel like the plague is also important.


Better than all of this is to use a day tank -- which my next boat will have.


Some people swear by fuel polishing setups -- surely won't hurt anything, but I doubt that this is a real substitute for normal tank inspection and normal cleaning.

I'm not really sure why my tanks stay so clean. They are steel, yet I've never seen a drop of water in the Racors, and when I cracked the starboard tank, in the lowest part of the tank I found essentially nothing. No corrosion, no sludge, no water. I use no biocide, although I do add Optilube, which will emulsify water, or so it says on the label. I only refuel annually, so its not like I run through the fuel quickly.

The only thing I can think of is that whenever a tank gets down to <5% of capacity, I polish it for 10+ hours whilst out in the slop. Even then, the amount of stuff picked up in the Racors is so trivial they don't need changing, even if I do for drill. Another possibility is that I can circulate 180 gph through the filters (their max - Racor 1000), so if there is only 50 gallons left what is there runs through the filter 30 times or so over the course of a day's cruise.

I think there are more dynamics to how dirty a tank gets than just the fuel you put in - existing contamination, water, others?

[a64pilot]

Originally Posted by Delfin

I'm not really sure why my tanks stay so clean. They are steel, yet I've never seen a drop of water in the Racors, and when I cracked the starboard tank, in the lowest part of the tank I found essentially nothing. No corrosion, no sludge, no water. I use no biocide, although I do add Optilube, which will emulsify water, or so it says on the label.

What brand of fuel do you buy? As you can imagine a lot of the better fuels already have biocide in them.

I’m convinced the majority of water in fuel comes primarily from the fuel deck fill. When did you lad change the O ring?
Other source is the vent, where is it, and how is it oriented?

[Dockhead]

Originally Posted by Delfin

I'm not really sure why my tanks stay so clean. They are steel, yet I've never seen a drop of water in the Racors, and when I cracked the starboard tank, in the lowest part of the tank I found essentially nothing. No corrosion, no sludge, no water. I use no biocide, although I do add Optilube, which will emulsify water, or so it says on the label. I only refuel annually, so its not like I run through the fuel quickly.

The only thing I can think of is that whenever a tank gets down to <5% of capacity, I polish it for 10+ hours whilst out in the slop. Even then, the amount of stuff picked up in the Racors is so trivial they don't need changing, even if I do for drill. Another possibility is that I can circulate 180 gph through the filters (their max - Racor 1000), so if there is only 50 gallons left what is there runs through the filter 30 times or so over the course of a day's cruise.

I think there are more dynamics to how dirty a tank gets than just the fuel you put in - existing contamination, water, others?

I have no idea, but my experience is the same, except without the on board polishing. Except my 700 litre tank is heavy welded alu plate, not steel.



It could be that larger tanks are less affected, because less contact with the tank walls. Or something. Or that recirculation through the main engine "polishes" the fuel. I really don't know.

[KWISPEL]

GTL Fuel works well but still not eassy to find out the Netherlands and Belgium.

[a64pilot]

I think people who regularly use their boat and either treat their fuel or buy treated fuel, have clean tanks.
Ever wonder why you don’t hear of these problems with Diesel Auto’s?
It’s because most of them are frequently used, and fuel is flushed if you will through the system, it doesn’t sit for months or maybe even years.

[Delfin]

Originally Posted by a64pilot

What brand of fuel do you buy? As you can imagine a lot of the better fuels already have biocide in them.

I’m convinced the majority of water in fuel comes primarily from the fuel deck fill. When did you lad change the O ring?
Other source is the vent, where is it, and how is it oriented?

I can see the refinery from where I refuel, so it is as fresh as it gets. No biocide is added, AFAIK. The filler pipes are capped with 2" pipe end caps, so no water can enter, and I routed the vent to the top of the pilot house though a "U" pipe, so no water can enter there. I am sure all of these contribute to fuel contamination elimination. I think you're correct of your suggesting that a lot of contamination comes from the weak points you mention.

[hamburking]

Originally Posted by NorthCoastJoe

When I got my Pearson 30 the first time I looked into the tank it was bad.

I also bought a 40 year old Pearson 30! However, the previous owner had some "trouble" the previous season...and told me he had the tank "cleaned" over the winter. I bought the boat with a completely empty tank. In hindsight, I think it was perhaps only flushed.

I should mention, the boat had been repowered with a volvo penta 2002 diesel (original was an A4 gas).

Sometime later, after a particularly rough day of sailing...the kind that really gets the tank sloshing around...I found the fuel filter totally filled with an organic sludge. Enough for me to replace the filter immediately, but apparently not enough to stop the engine, thank goodness.

Yes, I had the cockpit sole filler hole, but the O ring never did fail me, as far as I know. A bigger problem was that the fitting was marked GASOLINE. No service dock worker wanted to put diesel into a gas hole. I usually had to sign a waiver. Eventually, I just started using a fuel jug to top up, as I used very little fuel most of the time, being a sailboat.

No way to inspect the tank other than to peer down the hole. There was no fuel gauge. I measured the exterior dimensions of the tank, and did the math to figure it was about 70 litres. The tank, as other P30 owners will know, is a cylinder mounted horizontally. Obviously, 1/2 a tank would be 35 litres. But despite my good knowledge of math, I never could figure out how much fuel 3/4 of a tank or 1/3 of a tank was, in litres, when measured with a dipstick down the hole. The dipstick being a measuring tape.

The cockpit sole (floor), like most P30, was soft from water getting in around the rudder post. The fuel filler fitting had become the main structural element holding up the cockpit sole. I may be slightly exaggerating, due to my affliction to gravity. My kids never noticed a problem.

[leftbrainstuff]

No fluid, water, diesel, oil, enters our vessel unless I filter it.

Our tanks are inspected and cleaned by me, filters changed regularly, diesel is polished frequently and we only purchase fuel from bowsers with high turnover.

Diesel is a great host for bugs that live in the interface between diesel and water. Keep the water out, especially through your breathers and refueling and you'll rarely have problems. Breathers are a big issue. Allowing moist air in will see water condense our. Our breather is in our cockpit which is dry and warm.

I don't add biocide. Most good suppliers already add it and mixing some biocides in tanks that have water already may add to the problem.

Keep your fuel system clean and life will be good.

[Simi 60]

Zero biocide or treatments used by us but we do have a crud sump lower than the lowest point of the tank with a tap to drain off a litre, inspect for googlies and tip back in.
Fuel pick up is several inches above the sump.

Fillers and breathers are set in the cabin sides about 3 ft above the deck level so no real chance of water ingress.
Orings checked whenever we get "some" diesel and a bag of spares on standby for when needed.

This vessel had around 3500 litres (1/2 fill) of approx 10 year old diesel on board when we got her and she lives in tropical waters, so half full tanks don't seem to be an issue.
It was discoloured but didn't affect running and the crud sump ran clean.
After several months of running with zero vacuum showing on gauges we changed the filters so as I knew where we were at with maintenance and they were in as new condition.

[hzcruiser]

Originally Posted by crazyoldboatguy

The solution is a separate circulatory fuel polishing system that processes fuel at a much faster rate than your injector fuel return will. A fuel polisher like this one.

That's just another solution to fix the symptoms, not the root cause. As you mentioned yourself, it's the humidity and air borne spores that enter through the breathing line. Hence all you need is a suitable inline filter there.

[Singularity]

Points to ponder:

If you can grow biology without water you'll get a Nobel prize, the course of near and deep space exploration will be altered, and a means of reducing/eliminating human famine may be introduced. In other words, if you have growth in your tank, you have water in your tank.

The advice to keep a tank full is sound, but related to tanks that sit exposed to the elements (tractor, airplane). In those situations, quite different from sailboats, the concern is regarding the condensation specifically that occurs on the inside tank wall not in touch with fuel, such that when the tank is full, you don't get this tank wall condensation thing. But this is completely separate from the other condensation concerns/mechanisms below.

Insofar as every tank vents to the atmosphere, one cannot underestimate the power of diffusion and the dictum that water follows solute. One of my professors had the class chant "water follows solute" for over a minute to burn this into our heads. Sounds goofy, but this principle explains much of the behavior of water (on the microscale).

If we can agree that diesel is hygroscopic, then maybe we can agree that it's sort of a funny looking desiccant. So the question is, then, how does the water ever get out of the desiccant? Some of it burned with the fuel, sure. But warm fuel otherwise holds more water than cold fuel (just as warm air holds more water than cold air...the entropy thing).

Water entry through the vent is not a myth. It's an observable phenomenon that you can measure.
For the suck/trap/condense picture, see:
Water in Diesel - Clean Diesel Solutions - Donaldson
These guys don't give the calculation for measurement for the Boeing, but:
"it is estimated that as much as .14 liters of water could have been drawn through the fuel tank vent system en route to Heathrow."
https://lessonslearned.faa.gov/ll_ma...=79&LLTypeID=2
Practical Sailor did a review of vent line filters:
https://www.practical-sailor.com/iss...s_11303-1.html

As A64pilot said, water through the main fill fitting invariable is the likely culprit for most peoples' major water problem. I hate the flush-type fitting, but a thermos-style cap is not practical in most installations. If I was building a custom boat, I'd have some arrangement that was similar to an automobile fill door concealing a proper fuel cap.

The fact of the matter is that water readily collects in a place for removal...it just does so in a location that most peoples' pickup lines are not located. But clearly some boats are lucky. Regardless, assuming that fuel-water separating filter systems are not bogus, then running the filter system 24/7 while agitating the tank will remove the water from the tank to the 60-90ppm range (per the reference above). 24/7 is not practical, but it must be noted that it is possible. The $64k question is how much how often.

A dense but very good ~10 page study on the items in the title, including water aspects (otherwise comparing aluminum to SS coupons).
An Assessment of Alternative Diesel Fuels: Microbiological Contamination and Corrosion under Storage Conditions
Of note:
"Micro-organisms present in the original fuel samples were the dominant species characterized after 6 month exposure" {i.e. don't worry about your vent line introducing the bad guys}

https://pdfs.semanticscholar.org/07c...20d6bc3684.pdf

[Yak52]

Inspection hatches are a must in the tanks , so easy to look in there with a torch .
First thing I did , prevention is better than cure !

[thinwater]

Originally Posted by Dockhead

I think that's actually been busted as a myth. MaineSail did empirical tests and found no moisture being brought into a tank from "breathing".

No, it has not. Ask any licensed tank inspector. Mainesail is a brilliant guy. There are many, topics I would not challenge him on. But I've done 35 years in the refining industry as a chemical engineer and API licensed inspector, and his testing had several serious flaws. In fact, I have replicated condensation in tanks in the lab, as well as having seen thousands of examples in the field (tank roofs are notorious for corroding due to condensation--it is so common you are actually required to inspect the roof BEFORE entering the tank.


Depending on climate, tank installation, and useage, diesel tanks can be expected to absorb 1-10 ml per season. Use enough fuel and the fuel can simply absorb this. Large water accumulation are from other sources, generally filler leaks or poor vent location or installation.

[thinwater]

Originally Posted by a64pilot

I think people who regularly use their boat and either treat their fuel or buy treated fuel, have clean tanks.
Ever wonder why you don’t hear of these problems with Diesel Auto’s?
It’s because most of them are frequently used, and fuel is flushed if you will through the system, it doesn’t sit for months or maybe even years.

Bingo. Sometimes you have to point out the obvious.


Many sailors need to run the engine more, not less. Lengthening the season helps too.

[Recy]

Originally Posted by thinwater

No, it has not. Ask any licensed tank inspector. Mainesail is a brilliant guy. There are many, topics I would not challenge him on. But I've done 35 years in the refining industry as a chemical engineer and API licensed inspector, and his testing had several serious flaws. In fact, I have replicated condensation in tanks in the lab, as well as having seen thousands of examples in the field (tank roofs are notorious for corroding due to condensation--it is so common you are actually required to inspect the roof BEFORE entering the tank.


Depending on climate, tank installation, and useage, diesel tanks can be expected to absorb 1-10 ml per season. Use enough fuel and the fuel can simply absorb this. Large water accumulation are from other sources, generally filler leaks or poor vent location or installation.

What were the serious flaws in Mainsails testing?