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**noelex 77** · 06-05-2020, 08:30

Quote:

Originally Posted by a64pilot

I know as there is no way to get into the tank

This is not unusual and is another very good argument for fitting a fuel polishing system. You really want to do everything possible to keep the tank clean when access is difficult or impossible. Polishing is only one of these steps, but it is a very helpful one.

Dirty boat fuel tanks are not a figment of the imagination. Have a look at the photo posted in post #87 after only two years.

A 33 year old boat fuel tank is likely to be reasonably dirty even if you have access to clean fuel. Obviously it has not caused issues so far, but personally with a tank of this age that has never been cleaned I would want inspect the inside of the tank before embarking on any rough offshore voyage.

I have been lucky enough to own boats that have large inspection hatches in their fuel tanks, but other cruisers report some success using one of the cheap waterproof endoscope cameras. They are small enough to fit through small openings such as that required for the fuel gauge so it should be relatively easy to see if your confidence in the tank’s cleanliness is justified.

Lepke · 06-05-2020, 09:07

Fuel dock diesel pumps often have a spin on filter mounted before the hose. Usually there is a date. As a hobby, when I visit someone in a marina, I check out the fuel pumps and many times the date is a decade or more older. Water will collect in the bottom of the filter. After ten years of fuel, I'd bet the filter is mostly full of water.

**a64pilot** · 06-05-2020, 09:18

I have a borescope, plugs into a USB port I think. Bought it and never used it. It has a light as part of it.
Might be interesting to see what’s in there.
When I bought the boat 5 years ago, on delivery it clogged the pickup tube several times, right at the top of the tube where there is a 90 degree turn and the fuel shut off is installed, I got quite good at disassembling the fitting to clean it out, the clog looked very much like flesh colored Tofu, almost cottage cheese consistency, pretty obviously dead bugs. Boat had 500 hours on it in 27 years so it sat a LOT and again obviously got a bad case of bio growth.
This was happening on the ICW, so I lost sleep worrying about what would happen when we went off shore, I was afraid there was a layer about two inches deep of these dead bugs and of course rough seas would mix them up and we would be without the motor.

Didn’t happen though, I assume there had been a ‘Bug” problem, assume they had been killed with a biocide and the fuel professionally filtered / polished and they missed a few chunks.
Anyway in five years I have had no further problems, and interestingly when all that was going on the filter remained clean, it was just a few chunks.
In those five years I have put another almost 1500 hours on the motor which I assume amounts to over 1,000 gls of fuel, in a 57 gl tank. And have been in weather and seas that I didn’t enjoy, not survival situations, but enough to occasionally have her slam, and IP’s due hull shape, don’t slam, but in big enough seas, anything can occasionally, you know water over the bow, occasionally the prop ventilating as the stern gets lifted out of the water.

It’s been my experience with running Diesel fuel vehicles all my life, farm vehicles, PU trucks and boats, that if you use a biocide as a preventative measure and use the fuel you will have no problem.
Now the use of biocide for me is relatively new for me, I never used it in the days before ULSD and didn’t start using it until my experiences with aircraft, so it’s possible that it’s not needed, but it is in aircraft and of course fuel starvation in an aircraft is a bit more serious than it is in a sailboat.

I would guess that only a small fraction of boats have fuel polishers and many that do, they don’t do much if anything at all, use of a Racor 500 and a regular fuel pump and using dip tubes meant for a generator etc likely doesn’t do much at all, you really need a very high volume of fuel to get the heavy stiff sitting on the bottom of the tank moving so that it ends up in that filter, and that not happening with a little pump.

However there are many things that people became convinced they must have based on what they read on the Internet, but really don’t, fuel polishing units are I believe one of those things. Other than more possible places for fuel leaks to occur etc, I doubt that they do any harm, but I also doubt that they actually do much good, or how come the vast majority of boats that don’t have them, aren’t calling Seatow etc?
Some do, and many times it’s from a bio infestation, in fact I’d bet that the average person becomes aware of biocides through having had a bug problem.

A “proper” polishing system will remove a lot of impurities and much of any water, but it’s not going to remove biological growth, you can’t really remove most bacteria, just kill it, it’s too small to effectively filter without exotic means like centrifuges.
If you could filter down to or less than a half micron, then you could get the single bugs. But smallest filter I have seen is 2 microns and even then I’m sure it’s not an absolute 2 micron filter.

If you go for years without clogging fuel filters then you don’t have a problem and if you do start clogging filters, call a pro if you can’t get into the tank to clean it yourself. If your tanks are getting significant deposits in them in a couple of years, you need to get your fuel elsewhere, because most of us go decades and don’t have to have our tanks cleaned, unless we get a case of bugs, and that’s prevented by using a biocide.

**Pete7** · 06-05-2020, 09:40

Quote:

Originally Posted by a64pilot

Finally, just like any “magic” additive if it’s so darn good, why isn’t it already in premium fuels from the beginning, like say Valvtec that has a biocide added before you buy it.
Now I’d bet Valvtec actually does that in order to keep their fuel supplies pure and to save the hassle and expense of a supplier who gets a case of the bugs, think we have a problem, how about the guy with the 10,000 gl underground storage tank?

Our local marina treats diesel fuel with Soltron.

Some back ground reading on the history of Soltron which isn't straight forward:

https://xbee.com/technical-sheet/ori...t-composition/

**noelex 77** · 06-05-2020, 10:18

Quote:

Originally Posted by a64pilot

Didn’t happen though, I assume there had been a ‘Bug” problem, assume they had been killed with a biocide and the fuel professionally filtered / polished and they missed a few chunks.

If the tank has been professionally polished then that is a help. It sounds as if this fixed, or at least helped fix a tank problem.

These professional systems are quite different to installed fuel polishing systems, but providing they are well done the results seem equally good. The professional systems use high pressure and high volume pumps together with an adjustable wand that can spray in different areas of the tank. They are used infrequently, often only when a problem is detected, but some owners have the treatment done periodically, once a year or biannually.

Installed polishing systems are quite different. They use much lower volume pumps and filters, but depend primarily on the boat movement to stir up the tank. They operate much more frequently (ours runs most days) and filter much higher volumes of fuel, but at a slower rate.

Different systems, but similar goals and I suspect generally similar end results if done well.

**s/v Jedi** · 06-05-2020, 10:28

I’m now convinced that Startron is the same as Soltron. Startron is just the name that Starbrite uses for sales in the US. Bottles are the same as well.

Our resident expert Rod Collins wrote an article once where it had been used for a long time in a 30 year old tank (iirc). It failed to clean the sludge but no water and no corrosion. When you have a polishing system, enzymes are the way if you store fuel for a longer period.

Simi 60 · 06-05-2020, 10:34

Quote:

Originally Posted by s/v Jedi

If your tank is 10+ years old and you don’t have a sump with drain or a polishing system that draws from the tank bottom then I agree with Slug that crud will accumulate on the tank bottom. Using enzymes may keep tank walls clean (not when starting with a foul tank) the sludge is another matter that needs to be polished out for one part and mixed through the fuel again for the part that passes 30 micron filters. It requires circulation of the fuel incl. from the tank bottom where pickup tubes don’t reach.

The tank is 10+ years old and it does have a sump with a drain.
Samples taken every couple of months show no crud

Whilst it doesn't have a fuel polishing system as such, our engine does pull 330 litres/hour through the 10mic filters. 95% of that is returned to the tank.

Simi 60 · 06-05-2020, 10:38

Quote:

Originally Posted by slug

Gee, rather than wasting words simply open your tank and show me a picture

Hold on while I put 6000 litres of diesel in some jerry cans
Oh wait.............

How about the fact that I regularly drain the crud sump and get no crud and the filters are a couple of years old and show no vacuum when running?

**s/v Jedi** · 06-05-2020, 10:43

Quote:

Originally Posted by Simi 60

The tank is 10+ years old and it does have a sump with a drain.
Samples taken every couple of months show no crud

Whilst it doesn't have a fuel polishing system as such, our engine does pull 330 litres/hour through the 10mic filters. 95% of that is returned to the tank.

Yes, but do your engines pull that fuel from the tank bottom, or do the pickup tubes stop short of the bottom?

I had a setup like you, replaced the sump drain plugs with valves and connected the polishing system to that. Your pickup tube is probably right above the sump, stopping at the level of the tank bottom. This means you can drain the crud and water and you can use the full tank capacity. Still, a polishing system connected to the sumps is still a fantastic upgrade because it provides so many benefits besides just the polishing. Priming, pressurized fuel delivery, tapping clean fuel for filling filters, hooking up a jerry jug instead of using tanks, pumping up from drums etc. etc.

**a64pilot** · 06-05-2020, 10:53

Quote:

Originally Posted by s/v Jedi

Yes, but do your engines pull that fuel from the tank bottom, or do the pickup tubes stop short of the bottom?

Two schools of thought on that, one is leave a gap for junk to settle so that you don’t clog filters, I am not a proponent of that school of thought, but it’s very common most all boats are manufactured that way.
Another school is suck if from the very bottom, that way you pick up any Junk there is and put it in the filter, that’s the school of thought I ascribe to, and it’s easy, just put a proper length of rubber hose on the bottom of your dip tube ensuring it gets to the very bottom.
That way nothing builds up.

Aircraft suck from the very bottom, aircraft I flew had a total fuel capacity of 376 gls, with 375 of it usable. Military aircraft, the civilian one actually had more usable than we called its capacity to be as we didn’t count the 5 gl header tank in capacity.

Simi 60 · 06-05-2020, 13:28

Quote:

Originally Posted by s/v Jedi

Yes, but do your engines pull that fuel from the tank bottom, or do the pickup tubes stop short of the bottom?

I had a setup like you, replaced the sump drain plugs with valves and connected the polishing system to that. Your pickup tube is probably right above the sump, stopping at the level of the tank bottom. This means you can drain the crud and water and you can use the full tank capacity. Still, a polishing system connected to the sumps is still a fantastic upgrade because it provides so many benefits besides just the polishing. Priming, pressurized fuel delivery, tapping clean fuel for filling filters, hooking up a jerry jug instead of using tanks, pumping up from drums etc. etc.

The bolded bit is our setup.
Still, if draining the crud sump regularly shows no crud surely that means..........no crud.

I am sure if I busted open the hatch there probably would be something, but if its attached and not finding its way to the sump with regular use its as good as clean in my eyes.

**s/v Jedi** · 06-05-2020, 15:24

Quote:

Originally Posted by a64pilot

Another school is suck if from the very bottom, that way you pick up any Junk there is and put it in the filter, that’s the school of thought I ascribe to, and it’s easy, just put a proper length of rubber hose on the bottom of your dip tube ensuring it gets to the very bottom.
That way nothing builds up.

If tanks have no sump and there is a primary filter then yes this is the way to go. The reason many boats have tubes that stop short of the bottom of the tank is that they don’t come with a primary filter.

Our boat came with sumps that were plugged (for certification valves are not allowed so owners had to add those later) and a primary filter. Still, after emptying the tanks and opening the sump plug for the first time (10 years after delivery) crud or very dark fuel came out plus about an ounce of water.

**a64pilot** · 06-05-2020, 15:40

Yes actual bottom sump drains are not allowed, but nothing says you can’t have a top mounted tube that goes all the way to the bottom of the sump. Put an outboard squeeze bulb on it occasionally and suck some fuel out to inspect.
Above ground storage fuel tanks should be mounted at an angle with a drain at the lowest point that gets drained occasionally.
Below ground tanks can’t do that, that’s when the top mounted tube that goes all the way into a sump comes in, also there is a paste that you out on the stick when you stick the tanks, if it touches water it will turn from a goldish color to a bright purple. This paste can be used on a boat too of course.

https://www.amazon.com/s?k=water+det...b_sb_ss_i_1_21

I don’t want to, but if I have to replace my fuel and water tanks, there will darn sure be a sump drain, whether it’s an actual drain or a tube from the top, there will be a sump and a drain for it.

Back to the airplane thing, my little Maule had six sump drains, one for each tank and one for the gascolator, and an actual sump as in lowest point in the entire fuel system had a drain. To not have that in a boat is foolish, what’s more likely to get water in its fuel, an airplane or a boat?

What I have done in mine and any boat can do is hoist the dinghy on a halyard on the side of the boat, That puts it at a slight heel, then using hose meant for refrigerator ice maker water hose, use my oil change suction pump to vacuum the lowest edge of the tank, if you don’t get any water, there isn’t most likely any water to get, but you need to heel the boat so all water will go to the edge of one side of the tank.