How long did PS article suggest it would take for these to form in old diesel. It's my understanding that diesel is much more shelf stable than a winter layup would require. Still, I also find the condensation issue, for not having a full tank, to be partly myth. At best, it's dependent on individual climate, propensity for one's tank location to warm and cool, etc, etc. IIRC, @Maine Sail tried to recreate tank condensation in a test environment and could not.

The other factor I often wonder about is overdosing witchcraft additives and conflicts between them.

 

Looks like bugs. Bleach will usually cause a color change, but not always, depending on what else is caught up in the floc (agglomeration of bugs). It is not the bugs that have color, it is whatever they absorb or floc with.

Contrary to popular wisdom--and I've spent 40 years in the petrol industry as a chemical engineer--a free water layer is not required for growth. It really helps, but is not an absolute requirement. All that is required is the finest emulsion, which you certainly do have from time to time.

There is not fixed time period for bugs. Like pouring new milk in an old jug, the bugs are in there. Other aging effect should take at least several years, unless there is free water and corrosion.

The only way to be certain is dip slide testing (Google). Alternatively, just start dosing with Biobor. You will get increase filter sludge for a while, as the dead bodies slough off.

T

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Regarding condensation, this has been observed in the fuel industry for a century and is established fact. I have observed in the field (tank inspector) to the point of ruined tank roofs and I have recreated it in the lab. Typical sailor tests feature an empty tank--that is not realistic, because the drops that fall into the diesel in a real tank stay there, sealed in by the diesel, where as any droplets in an empty tank can evaporate. The temperature changes are also different.

If you want to eliminate it, use a silica gel vent filter. I believe they are one of the cheapest fuel quality investments for the occasional sailor. Or burn more fuel--it doesn't keep forever.

That said, it is very small amount, and water in the fuel nearly always comes from a bad filler seal or a poor vent design.

 

Thanks for your comments!

What is the shelf life of Biobor JF? I've been dosing with it at every fill-up (carefully measuring based on how much fuel goes in). I did a double-dose (shock level) after last filter change. But the bottle came from PO, age unknown. Should I dump it and buy new BioBor?

I've looked at H2Out, but the install will be very difficult due to restricted space around my vent hose.

For now, I'm going to try fuel management so that my fuel is fresher (rinse the "milk jug" before refilling it). My prior top-off method prevented breathing, but the fuel was 6 months old before I'd launch, and CSTR calculations based on the consumption rate from a full tank show that average fuel age would be almost 3 years in the tank.

Is there a product that can solubilize water in diesel? I would not want to use such a product on an ongoing basis, but might put it in a couple gallons of diesel at the beginning of the season to try to remove any trace water that might be below my pickup tube. Then burn it off early in the season and put in 1/3-1/2 tank of fresh diesel.

To me, the most shocking thing was how all of that brown stuff in my picture dropped out of the pump mechanism of my Racor filter. If it's biological, there was a big colony hiding in there. I think I'm going to have to exercise that pump mechanism on a regular basis, which I had never done before.

I check my fill top O-rings regularly and the fuel tank one is pristine. Waste tank O-ring is not pristine, but I have not yet found a replacement that's the right dimensions.

 

It is the only time I am thankful that I have a smaller sized ( 20 gallon) fuel tank. We run through the fuel fairly frequently enough so we don’t have stale fuel issues. That coupled with the large amount of nautical miles we travel each year helps to also prevent fuel stagnation issues. Last year we used about 120 gallons of diesel in our 3000 nm. That represents approximately 180 hrs of engine time. I change the filters every 50 hrs.

I am a proponent of filling the tank To full before leaving for the winter. Since I have been doing that I find nary a trace of water in the fuel. I don’t douse with large amounts of biocide either.

This works for us.

I know use of your boat is limited for you right now. I have found it’s good to run our Yanmar with a good load. I’m not afraid to do that. I used to sail immediately and then all the way back to the dock. I have changed that somewhat to incorporate 1/2 hour out when leaving ( I’m in the Bay in 20 minutes from the slip) and also the same on returning. If I cant sail into an anchorage and anchor under sail I makes sure Mr Yanmar runs 20 minutes.

 

P- have 4 50g diesel tanks. Usually will run one down to 20% left then move to another one. Usually run the aft starboard first. Rarely run port forward down. Usually top off tanks once or twice a year. Have never run all tanks to empty. Haven’t had a portable polisher out to boat since inception in 2013. Haven’t had any troubles. Compulsive about biobor.

what’s best practice? Run tanks to empty?or leave 20% so you don’t have sediment/water issues?
If you’re having no problems should you polish the entire contents of your tanks periodically? At what intervals?

 

Thats a lot of fuel/tanks to manage.
A big plus when needed

I would think...
Carry what you might use over 6 months..or x time period

Access to the inside of tanks seems to be a problem with many
Difficult to cure problems

Access to most things 'boat' is a pain

 

Access is actually quite good. All are under the sole. Just unlock and lift out a dedicated section for that purpose. Then unscrew access plate.
That’s not the issue rather was looking forward to pdq advice on best practices. Many boats top off where and when they can. Old is mixed with new. Boats commonly go quite a long time on a fill or top off. Especially where it’s windy. Sure you add biobor or like product but what else is advised to keep tanks clean, fuel that will burn nice and keep your engine happy.

 

Access is actually quite good. All are under the sole. Just unlock and lift out a dedicated section for that purpose. Then unscrew access plate.
That's not the issue rather was looking forward to pdq advice on best practices. Many boats top off where and when they can. Old is mixed with new. Boats commonly go quite a long time on a fill or top off. Especially where it's windy. Sure you add biobor or like product but what else is advised to keep tanks clean, fuel that will burn nice and keep your engine happy.

There is no simple answer for keeping fuel fresh for >3 years, particularly when fresh fuel is being added to an inoculated tank. It's tough. The reasons trucks have fewer problems is that they burn the fuel!

I've done long-term testing, and although most fuel will keep in a sealed bottle for 10 years, some "turns" in a just few years under perfect conditions. If there is some air exchange, some water present, a few bacteria, and a few copper and zinc ions, the fuel is at high risk of changing in 3-5 years. The best you can do is:
* Silica gel vent filter. We can debate whether there is significant condensation, the fact of the mater is that the gel does absorb a few ounces per year. I think it is a good deal. Vent filters also reduce the amount of air moving in and out of the tank by convection (currents).
* Replace fill o-rings and put a little grease on them. If they are in a low spot, move the fill (I had a boat with a badly positioned fill that was in a rainwater path--it leaked no matter what and I moved it).
* Treat regularly with Biobor JF or any other biocide that is listed as a pesticide. I've tested many, and they all work. Biobor is my first choice. Do NOT wait until you have an infestation. Not only will you have to clean the tank, the dead bodies will go through your injectors, which is bad.
* Use double filtration, like a Raycor.
* Polish or don't. The evidence seems mixed (it treats the problem, but it's not clear it prevents the problem).
* Run the motor more. There is no substitute for turnover.
* To fill or not to fill. If you use a silica gel vent filter, I think there is no good argument in favor of filling. And the vent filter is cheaper than a fill-up!! Getting fresh fuel is better.
* Use a good anti-corrosion additive. It is the ions that make the fuel unstable (much testing, by ASTM, engine makers, and Practical Sailor).https://www.practical-sailor.com/issues/37_32/features/Diesel-Additives_11083-1.html
* Avoid zinc and galvanized. Minimize copper alloys. I'm not sayin' rip stuff out... unless it is copper tubing fuel lines. The USCG got that all wrong, just ask the engine makers.

 

What reasons would preclude having and using a vent line shut off/closing valve

 

If the fuel or air expands due to heating the tank could burst. Many (most) tanks are not built to withstand any pressure. Damage can also be done by cooling. The damamge can be gradual fatigue of a welded seam. This is a real fundamental need.

 

Yes, but is the pre-treated Valvtect fuel sufficient to not needing more biocide?

 

Another curiosity. How long does BioBore last? You need very little. A quart bottle would last me an estimated 10 years!

 

No, I can't think of a reason to add more biocide.

I have tested samples of Biobor as old as 8 years. Carbamate types tend to crystallize after 3-5 years, but that is not a hard and fast rule. Personally, I give away additives that are more than 5 years old. My marina has a free-cycle bin, and they disappear in a few days.

 

The fuel pickup tube is typically some distance up from the tank bottom and that's where the creatures and water will lurk if you have them. On my friend's boat he had water it seems from a leaky filler cap. He wasn't getting any crud into his 500FG Racor filter but his fuel line actually got plugged right above the tank by greenish foliage once he got into a seaway. The Racor bowl was still pristine so those might not tell you so much. That little bit of stuff we see in your first photo would not be a problem for the filter element but if that exists in your tank there is trouble brewing. If your fuel is clean you could go 4 years on one filter element.
I used a brass plunger pump with a metal/rubber suction tube and sampled liquid from the very bottom of his rather tall 40g tank into glass jars to see where it was at. It was loaded with algae florets and he clearly needed polishing. Perhaps his steel tank is at some risk from possible corrosion -- in retrospect. There was a recent article in a magazine ('This Old Boat'?) about a skipper that built his own fuel polishing rig.
If the fuel pickup tubes on tanks actually went down to the very bottom I think we would not have a hiding zone for cultures to grow and the primary filter could do its job continuously rather than intermittently. This practice seems to be a misplaced attempt to simulate tanks that have collection sumps and drains which can avoid these issues. Yanmar actually offers tanks for above-deck installation with these features meant for small fishing boats.

 

We have owned this boat since 1994. There has never been a trace of water or any visible crud in the bowl in our Racor, on the former Universal diesel engine or the Betamarine I replaced it with in 2018.
I do add a bit of 'bug killer' with each fill.

This last summer, tho, I did have to remove the tank and have a microscopic hole welded up. This was from a drop of water that stayed in one place on the low side of the tank bottom. After talking to a couple of boatwrights, I do believe that emulsified water does come in sometimes with fuel and can then separate out inside the tank. Out tank outlet is at the lowest point, but this point is about a half inch above the bottom.

With 2020 hindsight, I should have removed the inspection ports at least every other season and swabbed out the low corner with some water-absorber material.
My intuition is also that more movement of the boat when under power stirs up the fuel well and water drops (and small solids) get trapped in the Racor. We have not been on an extended offshore passage since 2014, so there's another reason to go offshore more often!

No new wisdom here, except to take measures against water/moisture as well as potential dirt and 'critters' in your fuel.

 

Are the non-alcohol based water absorbing additives effective? Alcohol/ehtanol are awful, as I understand them. This is advertised by USAFuel. Possibly Xylene, but that may be the cleaner, not the water absorbent. A few boatyards around here swear by the stuff to clean up small amounts of water in the tank.

 

I think you will find that all engine manufacturers advise against water absorbing additives. I know some of the engineering department guys (for 20-30 years) and they really don't like the idea. They would prefer you use a Raycor, sump the tank, eliminate leaks, and burn enough fresh fuel to suck up the rest. You won't get a recommendation. They prefer additives that create a clean break. Star Tron is good that way. Also helps with corrosion. Stabil Diesel is good against corrosion.

 

Pdq you are a resource. Thanks for sticking around. Also learn good useful stuff when you post.

 

This is a great thread!

I am happy to see that someone else agrees with me about how condensation, especially when the tank is partially full, can lead to water in your fuel. The only additional advice that I can contribute is to close the vent (I use blue painter's tape) when the boat is laid up for several months to keep moisture out.

 

Thats is my thinking.
Id go 1 wrap of elec tape...easy to bust out...low pressue
Could also stopper/cork the hose

 

A quick update, comments, and a few questions:

Regarding my bleach staining test in my original post, it occurred to me that having the muck saturated with diesel fuel might have prevented the bleach from actually reaching the fibers (due to its insolubility in diesel fuel), and thus skewed the results. So I allowed the sample to dry for a few days and applied some more bleach to the dried sample. There's still no change in color, so I think the sample has at least some asphaltenes.

Out of an abundance of caution, a few days ago I ordered some fresh Biobor, since my current 16 oz bottle is of unknown age, but it's likely >10 years old. During my boat's late October journey to winter storage I was using untreated diesel fuel, so yesterday I treated the ~5 gallons of fuel remaining in the tank with 1/2 tsp of Biobor and 2 tsp of Star-tron Enzyme (with about a quart of diesel fuel as chaser). I have no way to mix this up with the boat on the hard (unless there's an earthquake), so I'm letting it sit for a couple of days and then will pump it through my fuel loop using the manual pump on my Racor filter. After that hope I can get access to my fuel tank to pull off the gauge sender and reach in to pump out the fuel tank contents for storage at home, where I'll inspect it and decide whether to dispose of it or try to manually filter it.

The discussion here brings up the valuable question of what "cocktail" of additives we should use for protection against bacteria, corrosion, water contamination, and lubricity replacement for newer ULS fuel. Pre-treated Valvtect fuel is no longer available around here, so I need to find additives. (Note also in the attached report that Valvtect Diesel Guard addtivite actually makes lubricity worse than untreated ULS fuel.) And, FWIW, I buy all my fuel at busy land-based fuel stations because I always think that they are less likely to have water contamination than marinas.

The discussion of using multiple additives is potentially complicated because of the potential for them to attack each other with competing chemistries. In another post last fall I referred to the old Steven Wright joke about putting a humidifier and a dehumidifier in the same room together.

For the first year with my current boat, I used Biobor JF and Star Brite EZ Store EZ start, which were the two additives that the previous owner left behind. Then, after reading the well-known lubricity additive study (see attached picture), I replaced the EZ Store with Opti-Lube XPD, which was rated very high for lubricity properties. I was concerned that the two might interfere with each other because EZ store says it's an emulsifier, while Opti-Lube says it's a demulsifier. I've run out of the Opti-Lube, so will either order more for spring launch or find something else based on recommendations that I get here.

After re-reading the Practical Sailor articles, I've added the StarTron Enzyme additive for corrosion protection in addition to the BioBor JF. These seem consistent with Practical Sailor's recommendations, though I'd appreciate comments on whether to re-order the Opti-Lube or find another lubricity additive.

 

^^^ The color can also come from corrosion products (rust and other).

 

Good point, I should have said "something other than bacteria".

I'm curious what would cause a brown corrosion product. My tank is aluminum, which I think would have white corrosion solids. There are some brass fittings on the hose barbs on the Racor Which could be red+green=brown, and I know from your multiple articles that brass is a bad actor. What else should I look for? For now, I've started using the Startron enzyme. Are there other anti-corrosion additives I should try?

 

Been advised to
Use biobor at the conditioning dose at every fill.
Never fill shortly after fuel dock gets new fuel. Crap in the bottom of their tank(s) gets stirred up so better to wait until that settles. Also ask when they last got new fuel and how much is left. You don’t want to get fuel just before they’re due for a refill.
Fill at a high volume turn over fuel station. In most places that means that’s where the commercial crowd goes.
Use startron enzyme.
Avoid using return from one tank to fill a different tank. We have 4 tanks so could easily use this technique to put fuel in windward tanks to improve trim while sailing. Told a bad idea as you could transfer bugs and contamination.
Drain, replace filters, refill your racors periodically.

What I don’t understand is how often you should prophylactically replace racor filters?
Is there any benefit to prophylactically polishing all your fuel with a dockside device?
PDQ posts have been most helpful. But the devils is in the details.

 

People talk about before filling their tanks taking some to fill a glass jar and waiting to see how it looks. We carry glass for this purpose but haven't been able to do this. Fuel dock people just want to move you along. There’s often other boats waiting in line as you fill.
Does anyone know a quick way to check out fuel?

BTW we used to always have dish detergent to drop into the water to break up any small spills. Have stopped doing that as told it really doesn’t help but may rather make things worse. Better that fuel sits on the surface than be dispersed into the water. Thoughts?

 

While one should take every precaution not to allow fuel into the water, a few drops of diesel or gasoline from a vent just isn't an environmental disaster. It will evaporate. Apologize to Poseidon and move on.

 

While shamefully discredited these days, Bill Cosby had an old skit on why kids could do such amazing gravity defying feats. It was because no one had taught them about gravity yet!

Good parallel to all the witchcraft we put in our fuel. Biocide in diesel makes sense. What doesn't make sense is that ALL marine diesel doesn't come inoculated. However, I bet everyone is guilty of doing just fine, until they read of a latest additive concept and then they have to have it.

 

RE: @outbound query about fuel filter replacement; here is a data point

I am still using the 50u filter in the Facet fuel pump, the R24p (30u) primary, and the WIX 33390 (10u) secondary filters that I installed in 2014, approximately 6 years and 450 engine hours ago.​

I have never found water or gunk in the bottom of the Racor. My M25 burns about 0.30 gallons per hour, and my aluminum tank holds 30 gallons. I fill the tank if it reaches ½, and add Sta-Bill for diesel every time add fuel. I cover the fuel vent with blue painter's tape every winter, and I have replaced the deck fill cap after 4 years - before the seal shows any signs of age (I also keep a spare aboard).

I believe that a common way that water enters the fuel system is from a degraded O-ring on the filler cap.

 

I just recalled a scenario, where I found a bunch of black sediment in the bottom of my Racor. It was enough that it was clogging the drain and I had to remove it all, disassemble and clean it out. I used the occasion to rebuild the Racor with new gaskets, etc.

Once nice and clean, I decided I better have the tank pumped, the fuel polished and the tank cleaned. They found very little contaminants in the tank, less than I found in the filter. I asked the vendor about my filter observation and he said "your filter did it's job, don't worry too much about it". Not bad advice.

 

I finally made it to the boat and drained the fuel tank yesterday.

I had hoped to pump the tank out by removing the fuel gauge sensor and putting a battery powered pump in the opening. (Other Catalina 34 owners have done this.) Unfortunately, I discovered that my tank compartment is too tight to do this, so I had to pull the hose off the Racor inlet and drain it by gravity. I pulled the first couple pints into a clear container so I could inspect it. It looked very clean.

I also discovered that my fuel tank is plastic, so that would seem to blow away any theory that the muck in my Racor is corrosion.