BruceK
Moderator Emeritus
- Joined
- Oct 31, 2011
- Messages
- 13,347
- Vessel Name
- Sojourn
- Vessel Make
- Integrity 386
Sob. Please stop it.
Last marina price here: $1.20 a liter, land filling stations down to $1.08.
Fuel questions....
- Thread starter dhays
- Start date
The friendliest place on the web for anyone who enjoys boating.
If you have answers, please help by responding to the unanswered posts.
If you have answers, please help by responding to the unanswered posts.
Last marina price here: $1.20 a liter, land filling stations down to $1.08.
psneeld
Guru
Does An Empty Tank Condensate? Photo Gallery by Compass Marine How To at pbase.com
Make up your own mind...but my experience with dozens of salvaged tanks lying around a yard and a shop for years never have enough condensate in them to spit at. My mostly empty tanks never have condensate in them. Boats from Florida, to Mobile, Al, to NJ. Not positive but maybe the most humid part of the US?
Most experts I know now admit the full tank legend mainly came from insurance companies insisting gas boats be topped off to prevent explosions...not worry about condensation.
Especially now with ethanol fuel...many old timers are saying store empty if you can, or full if you can...mostly about ethanol and moisture...not condensation. Diesel is "whatever"....
Can condensation be a problem? Maybe...never have seen definitive proof of it though.
Make up your own mind...but my experience with dozens of salvaged tanks lying around a yard and a shop for years never have enough condensate in them to spit at. My mostly empty tanks never have condensate in them. Boats from Florida, to Mobile, Al, to NJ. Not positive but maybe the most humid part of the US?
Most experts I know now admit the full tank legend mainly came from insurance companies insisting gas boats be topped off to prevent explosions...not worry about condensation.
Especially now with ethanol fuel...many old timers are saying store empty if you can, or full if you can...mostly about ethanol and moisture...not condensation. Diesel is "whatever"....
Can condensation be a problem? Maybe...never have seen definitive proof of it though.
Last edited:
Actually, I've never experienced or had knowledge of condensation in diesel tanks and I don't know if that's the fuel or the quality tanks typically on diesel boats. I do know in small gas boats on the lake it was a legitimate issue. I have known those with 25 and 30 gallon tanks to have water at the start of a season and I have seen it in smaller six gallon tanks myself. Again, I can't speak as to the why or wherefore and I have no experience seeing it on larger boats with diesel and bigger, perhaps better built, tanks.
psneeld
Guru
Or water from other sources which is more often the cause.
Have had many a marina blame it on condensation only to have the boat towed in mid season from water getting in vents, necks, fillups, etc.
Not saying it can't happen...but is more rarely an issue than a common one.
Have had many a marina blame it on condensation only to have the boat towed in mid season from water getting in vents, necks, fillups, etc.
Not saying it can't happen...but is more rarely an issue than a common one.
That's why I made it clear I'm not certain as to the cause or circumstances. Just that's where I think the concern originated rather than the type boats we're dealing with. The majority of water I've seen on larger boats has either come from the fuel supplied or in more cases come in around the fill or vent.
timjet
Guru
- Joined
- Apr 9, 2009
- Messages
- 1,920
My experience,
When I bought the boat it had not been used in some time. I thought I had a fuel biocide problem and used a tank cleaner and biocide preventive for 3 years. It turned out I had a vacuum problem. I stopped using the additives and haven't had a problem once I figured out the vacuum issue. I believe Tony Athens on boatdiesel does not recommend additives but you should check.
I try to keep my tanks full. One warning; if you store for the winter and have a plastic heat shrink cover, if the tanks are full heat can build up and vent fuel. Depending on where you store the boat that can be an expensive cleanup even if just a gallon or two vented.
When I bought the boat it had not been used in some time. I thought I had a fuel biocide problem and used a tank cleaner and biocide preventive for 3 years. It turned out I had a vacuum problem. I stopped using the additives and haven't had a problem once I figured out the vacuum issue. I believe Tony Athens on boatdiesel does not recommend additives but you should check.
I try to keep my tanks full. One warning; if you store for the winter and have a plastic heat shrink cover, if the tanks are full heat can build up and vent fuel. Depending on where you store the boat that can be an expensive cleanup even if just a gallon or two vented.
FF
Guru
- Joined
- Oct 12, 2007
- Messages
- 22,552
"Most experts I know now admit the full tank legend mainly came from insurance companies insisting gas boats be topped off to prevent explosions...not worry about condensation."
Today most gasoline boats attempt to have all tanks empty , except the last tank , and will sit with that as empty as possible.
Before use the boat will be filled for the use and returns to the slip as empty as can be done.
This is because the mandated Ethanol in fuel gives gas a 30 day life at best.
The folks that have access to non poisoned fuel pay more at the pump , but have fewer fuel problems.
IF they succeed in raising the alcohol level in diesel to 15% , we all will be using a different fuel management system than today.
The old glass bowl and water sock will probably make a big comeback.
Today most gasoline boats attempt to have all tanks empty , except the last tank , and will sit with that as empty as possible.
Before use the boat will be filled for the use and returns to the slip as empty as can be done.
This is because the mandated Ethanol in fuel gives gas a 30 day life at best.
The folks that have access to non poisoned fuel pay more at the pump , but have fewer fuel problems.
IF they succeed in raising the alcohol level in diesel to 15% , we all will be using a different fuel management system than today.
The old glass bowl and water sock will probably make a big comeback.
psneeld
Guru
Those were specifically the type of boats I was towing with water in the fuel...NOT from condensation.
Condensation troubles is just not the urban legend people keep passing on.
Small tanks are even less likely, especially the ones crammed into smaller boats and wind up having less thermal swings to induce condensation.
I felt alone in this issue when everyone was blaming ethanol for engine problems...I did a lot of research and discussions with fuel distributer guys, marinas, boaters, etc.
Then Compass marine did the study and was the first "study" I had really ever seen geared towards boat tanks. That pretty much confirmed my research.
Even Pascoe who a lot of people disagree with on some things agrees on this...
The Myth of Condensation in Fuel Tanks by David Pascoe: Boat Maintenance, Repairs and Troubleshooting
Another source pointing out an empty 200 gallon tank holds less than an ounce of water...and doesn't explain that most will evaporate back as the day warms up unless you fill the tank right after the moisture condensates onto the tank....
Water Contamination in Fuel: Cause and Effect - American Filtration and Separations Society
I know condensation is scientifically possible in a tank...and some might form in some situations...but people like me have specifically looked for it for years and have never found it in amounts to even worry about or found any at all.
Last edited:
Having operated a boat yard for many years the condensation issue and tanks was one that was discussed on many occasions. Many boat owners wanted their tanks full for the winter to avoid this possibility.
Curiosity got the best of me one winter and I decided to conduct an experiment. I made it a point to stick my head inside a few tanks, using the inspection ports that left in place but not screwed down, over the course of the winter, every couple of weeks, one each steel, aluminum and FRP.
It's important to understand how condensation forms, in tanks or anywhere else. The best analogy is the cold beer bottle, on whose surface water, condensate, accumulates. It occurs because the bottle is cold and the water in their air, when it makes contact with the bottle, reaches its dew point. This scenario must exist for condensation to form, condensation does not form in humid weather unless the tank's inside surface is colder than the water laden air, cold enough again to reach its dew point. Furthermore, the moist air has to get inside the tank, through the vent. The tank can "pant" with temperature changes, however, it isn't exactly a wind tunnel of air movement.
Water can evaporate and condense on overhead surfaces, however, in fuel tank scenarios the water is trapped beneath he fuel, making this unlikely.,
Where I live, in Southern Virginia, it's a condensation-prone environment, weather patterns sweep through the area bringing extreme temperature and humidity changes for much of the winter and spring (just this past weekend it swung for 80F to 34F in one day). If the weather is cool, and a warm moist front moves through, condensation will form on many surfaces, including deck hardware, and engine blocks, objects that remain cold for some time, and even fiberglass itself. Conversely, cold air sweeping in over a previously warm surface has no such effect.
The results of the above-mentioned condensation test...on no occasion did I ever see a drop of condensation form. Now this is hardly scientific, but I do believe it puts things in perspective. When conducting vessel inspections I do often find condensation forming on the inside of fuel fill caps. These are on deck and subject to cooler temperatures at night, so it makes sense that condensation will form on them. That does represent water in the tank, which isn't good.
Curiosity got the best of me one winter and I decided to conduct an experiment. I made it a point to stick my head inside a few tanks, using the inspection ports that left in place but not screwed down, over the course of the winter, every couple of weeks, one each steel, aluminum and FRP.
It's important to understand how condensation forms, in tanks or anywhere else. The best analogy is the cold beer bottle, on whose surface water, condensate, accumulates. It occurs because the bottle is cold and the water in their air, when it makes contact with the bottle, reaches its dew point. This scenario must exist for condensation to form, condensation does not form in humid weather unless the tank's inside surface is colder than the water laden air, cold enough again to reach its dew point. Furthermore, the moist air has to get inside the tank, through the vent. The tank can "pant" with temperature changes, however, it isn't exactly a wind tunnel of air movement.
Water can evaporate and condense on overhead surfaces, however, in fuel tank scenarios the water is trapped beneath he fuel, making this unlikely.,
Where I live, in Southern Virginia, it's a condensation-prone environment, weather patterns sweep through the area bringing extreme temperature and humidity changes for much of the winter and spring (just this past weekend it swung for 80F to 34F in one day). If the weather is cool, and a warm moist front moves through, condensation will form on many surfaces, including deck hardware, and engine blocks, objects that remain cold for some time, and even fiberglass itself. Conversely, cold air sweeping in over a previously warm surface has no such effect.
The results of the above-mentioned condensation test...on no occasion did I ever see a drop of condensation form. Now this is hardly scientific, but I do believe it puts things in perspective. When conducting vessel inspections I do often find condensation forming on the inside of fuel fill caps. These are on deck and subject to cooler temperatures at night, so it makes sense that condensation will form on them. That does represent water in the tank, which isn't good.
psneeld
Guru
Add another "observer" with keen interest...
From my research, it is the somewhere in the mid fuel range that has the greatest chance of forming condensation...that's due to the thermal mass of the liquid compared to the air in the tank.
But again, a half full 200 gallon tank contains less than 1/2 ounce of water in the air under idea conditions. Only a fraction of that could condense and actually work it's way to the bottom of the tank. This would only occur on "perfect days"...the rest of the time, there is none forming.
Urban legend to a GREAT degree until MIT or some other lab starts a time lapse experiment (like out anchoring videos
) and I can watch it accumulate to some degree of importance. 
From my research, it is the somewhere in the mid fuel range that has the greatest chance of forming condensation...that's due to the thermal mass of the liquid compared to the air in the tank.
But again, a half full 200 gallon tank contains less than 1/2 ounce of water in the air under idea conditions. Only a fraction of that could condense and actually work it's way to the bottom of the tank. This would only occur on "perfect days"...the rest of the time, there is none forming.
Urban legend to a GREAT degree until MIT or some other lab starts a time lapse experiment (like out anchoring videos
) and I can watch it accumulate to some degree of importance. Another factor that often was misleading on boats on the lake. Boat sits all winter, mostly empty of fuel, owner gets it filled for the start of the season. Water in fuel. He's instantly told it's from condensation over the winter. It actually came from water in the marina's fuel. I've seen marinas in total denial telling owners everything they could except the truth.
sunchaser
Guru
- Joined
- Apr 9, 2008
- Messages
- 10,195
- Location
- usa
- Vessel Name
- sunchaser V
- Vessel Make
- DeFever 48 (sold)
I was on a yacht yesterday that has 7,500 gallon fuel capacity. Tank levels and cruising plans balanced with tagging fuel before and after filling is practiced. They have put their efforts into good fuel and filtration systems rather than fuss with fuel levels and condensation worries.
psneeld
Guru
In USCG Aviation....we used to do what was known as a clear and bright test when filling the helicopters...thought about doing it for the boat...just cant get motivated till I leave areas that always seem to have good fuel.
http://petrovalue.ca/sites/default/files/3/PetroValueAviation%20Fuel%20Handking%20%20Jet%20Fuel%20Quality%20and%20Test%20Procedure%20Manual%202008.2_0.pdf
1.1 Clear andBright Test:
Deliveredfuel must be clean, bright and not contaminated with free water.
“Clear”is a visual condition of fuel with the absence of cloud, emulsion, visible particulatematter or entrained water. “Bright” is the quality of fuel refers to the
shinyand sparkling appearance of clean and dry fuel.
The“bright and clear” condition of the fuel is not dependent on the natural colour
ofthe fuel.
The“Clear and Bright” test is a visual check and conducted to detect water or
othersolid contaminants in the fuel. An evidence of external contaminants renders
thefuel as “not suitable for use” and points to a requirement of furtherlaboratory
analysis.
http://petrovalue.ca/sites/default/files/3/PetroValueAviation%20Fuel%20Handking%20%20Jet%20Fuel%20Quality%20and%20Test%20Procedure%20Manual%202008.2_0.pdf
1.1 Clear andBright Test:
Deliveredfuel must be clean, bright and not contaminated with free water.
“Clear”is a visual condition of fuel with the absence of cloud, emulsion, visible particulatematter or entrained water. “Bright” is the quality of fuel refers to the
shinyand sparkling appearance of clean and dry fuel.
The“bright and clear” condition of the fuel is not dependent on the natural colour
ofthe fuel.
The“Clear and Bright” test is a visual check and conducted to detect water or
othersolid contaminants in the fuel. An evidence of external contaminants renders
thefuel as “not suitable for use” and points to a requirement of furtherlaboratory
analysis.
We do that and a test for acidity. There are also tests available for ethanol. These may be useful especially for those using gas in areas where E15 is being sold.
OP
OP
dhays
Guru
- Joined
- May 26, 2015
- Messages
- 9,045
- Location
- United States
- Vessel Name
- Kinship
- Vessel Make
- North Pacific 43
PSneed, that sounds pretty much like what I used to do back when I flew little Cessnas around the countryside. Drain a bit of fuel from each wing tank and look to make sure it was clear and had no water. I actually never remember ever finding water in the fuel and it was always clean and clear. Rental aircraft that got flown a lot and a good fuel supplier I guess.
We used to dump the sample on the tarmac. I imagine that would create all kinds of trouble now.
We used to dump the sample on the tarmac. I imagine that would create all kinds of trouble now.
- Joined
- Oct 1, 2007
- Messages
- 7,331
- Location
- Texas
- Vessel Name
- Floatsome & Jetsome
- Vessel Make
- Meridian 411
No additives here. I burn it as fast as I can. I only have a 320 gallon capacity. I wish I had more.
Are Valvetech additives really added by the end seller and not somewhere upstream of that???? My Marina sells the stuff and that is what I burn most of the time. I guess I need to do some snooping around to make sure I'm not getting snowed.
Are Valvetech additives really added by the end seller and not somewhere upstream of that???? My Marina sells the stuff and that is what I burn most of the time. I guess I need to do some snooping around to make sure I'm not getting snowed.
psneeld
Guru
Check it out...but I am pretty sure it is added after the fuel goes to the local distributer....so whether he adds it at fill up at the local distributer...or only into the marina tank because half the load is going somewhere else is the question you need to ask.
Remember it IS an additive that the refiner doesn't already have in the fuel...it has to be added and the refiner is selling to everyone...not just Valvetec sellers.
At the marina I was referring to...it was the responsibility of the marina to add it.....so there ya go...how much do you trust everyone there from the manager to the fuel dock kid that was asked to do it at 5:30 on Friday afternoon after a fresh fuel load?
All fuel gets additives added at the terminal. Up until that point it's just generic. Quality of gas is heavily advertised based on the additives with detergent being the most common. Detergent is in all gas, but then some brands have triple the required amount.
Terminals have reasonably good control of their processes of adding additives. Also, brands like Valvtect do semi annual testing at the pumps to be sure their standards are maintained. I won't argue that Valvtect always arrives to your tank with the exact makeup of additives it's supposed to. However, I will argue that it generally will have those additives.
Now, while we use Valvtect as the company that delivers to us is a Valvtect supplier, I don't know that it's better than other brands. For cars I'm not convinced brands hold an advantage. For boats, I'm inclined to think they do. I think Valvtect does a good job with the biocide toward managing bacteria and algae and toward stabilizing the fuel for a longer time. I think most branded gas does benefit from the added detergent.
Now often the unbranded marina or station might actually be getting the branded fuel, buying on the grey market but not allowed to advertise it. Most marinas in the US are branded though.
I'm comfortable with most brands, more so with Valvtect. Also, when out of the country or not certain of what fuel we're getting we do add Bioguard. We do not add it when purchasing branded fuel in the US (unless a marina we're skeptical of but had no choice).
This is one of those areas I don't have a controlled trial. I can't run one engine on unbranded diesel and the other on Valvtect and compare them year by year. I just believe using a good brand of fuel to be safer and at the very least it makes me more comfortable.
Terminals have reasonably good control of their processes of adding additives. Also, brands like Valvtect do semi annual testing at the pumps to be sure their standards are maintained. I won't argue that Valvtect always arrives to your tank with the exact makeup of additives it's supposed to. However, I will argue that it generally will have those additives.
Now, while we use Valvtect as the company that delivers to us is a Valvtect supplier, I don't know that it's better than other brands. For cars I'm not convinced brands hold an advantage. For boats, I'm inclined to think they do. I think Valvtect does a good job with the biocide toward managing bacteria and algae and toward stabilizing the fuel for a longer time. I think most branded gas does benefit from the added detergent.
Now often the unbranded marina or station might actually be getting the branded fuel, buying on the grey market but not allowed to advertise it. Most marinas in the US are branded though.
I'm comfortable with most brands, more so with Valvtect. Also, when out of the country or not certain of what fuel we're getting we do add Bioguard. We do not add it when purchasing branded fuel in the US (unless a marina we're skeptical of but had no choice).
This is one of those areas I don't have a controlled trial. I can't run one engine on unbranded diesel and the other on Valvtect and compare them year by year. I just believe using a good brand of fuel to be safer and at the very least it makes me more comfortable.
Added at the local terminal. Added to all their fuel, even if they deliver some to a non-branded marina or service station. Not added at the marina tank.
I have no connection with ValvTect, however, I believe the ValvTect retail fuel supply concept has merit - the notion of guaranteed on spec, water-free fuel is hard to argue with. I've been to their facility in Chicago and the plant that makes their (and other's) additives, they seem intent on delivering a quality product and take, and investigate, customer complaints very seriously, again in my experience.
Having said that, ValvTect doesn't refine fuel, the fuel still comes from a wholesale rack supplier, one that is approved by ValvTect. ValvTect spot checks their distributors' fuel and tanks for quality and water content. When the fuel is delivered to the retailer the ValvTect cocktail is added. I've watched this process on several occasions, and photographed it. In one case, after adding about half the fuel to the storage tank, the driver of the delivery truck (not marina staff) opened a bin attached to the chassis and removed a graduated plastic measuring cup and a jug (labeled "Valvtect Marine Premium Diesel Additive with Bioguard Microbicide, the jug of gasoline additive, was labeled with a Sharpie, "gas additive") of the ValvTect additive. He poured in what I assume was the appropriate amount of additive for the diesel quantity he was delivering.
Is there an opportunity for errors to occur in this process? I would say yes. Lubricity, detergent and other retailer-specific additives are nearly always added at the "fuel rack" by the way, where fuel is dispensed into the delivery truck. You've noted no doubt that fuel being delivered to Shell, BP and Exxon gas stations isn't delivered exclusively by those refiners' own trucks (anymore), the fuel is generic and "additivised" in fuel industry parlance, with those companies' specific additives to make them unique, Shell's V-Power, Chevron with Techron etc. at the rack, and I've been told by wholesalers those additive systems sometimes fail, meaning some fuel doesn't get the additives specific to its brand. In most regions in the US there may be one pipeline or refiner that provides fuel. Where I live, virtually all truck fuel I've ever purchased for marine use comes from a refinery in Yorktown, Virginia and/or via the Colonial Pipeline (if you like this kind of stuff, the history of this pipeline, which first transported fuel in 1963, and runs from Texas to New York Harbor, passing through many major airports, is fascinating, it's actually two lines, one for gasoline and the other for jet, diesel and heating oil). Otherwise, with very few exceptions, the fuel is generic before being additivised.
Having said that, ValvTect doesn't refine fuel, the fuel still comes from a wholesale rack supplier, one that is approved by ValvTect. ValvTect spot checks their distributors' fuel and tanks for quality and water content. When the fuel is delivered to the retailer the ValvTect cocktail is added. I've watched this process on several occasions, and photographed it. In one case, after adding about half the fuel to the storage tank, the driver of the delivery truck (not marina staff) opened a bin attached to the chassis and removed a graduated plastic measuring cup and a jug (labeled "Valvtect Marine Premium Diesel Additive with Bioguard Microbicide, the jug of gasoline additive, was labeled with a Sharpie, "gas additive") of the ValvTect additive. He poured in what I assume was the appropriate amount of additive for the diesel quantity he was delivering.
Is there an opportunity for errors to occur in this process? I would say yes. Lubricity, detergent and other retailer-specific additives are nearly always added at the "fuel rack" by the way, where fuel is dispensed into the delivery truck. You've noted no doubt that fuel being delivered to Shell, BP and Exxon gas stations isn't delivered exclusively by those refiners' own trucks (anymore), the fuel is generic and "additivised" in fuel industry parlance, with those companies' specific additives to make them unique, Shell's V-Power, Chevron with Techron etc. at the rack, and I've been told by wholesalers those additive systems sometimes fail, meaning some fuel doesn't get the additives specific to its brand. In most regions in the US there may be one pipeline or refiner that provides fuel. Where I live, virtually all truck fuel I've ever purchased for marine use comes from a refinery in Yorktown, Virginia and/or via the Colonial Pipeline (if you like this kind of stuff, the history of this pipeline, which first transported fuel in 1963, and runs from Texas to New York Harbor, passing through many major airports, is fascinating, it's actually two lines, one for gasoline and the other for jet, diesel and heating oil). Otherwise, with very few exceptions, the fuel is generic before being additivised.
FF
Guru
- Joined
- Oct 12, 2007
- Messages
- 22,552
"it's actually two lines, one for gasoline and the other for jet, diesel and heating oil). Otherwise, with very few exceptions, the fuel is generic before being additivised."
This is the key , all comes from the same pipe .
If you want to be sure of your fuel, filter it for gunk and water as it comes aboard , and pour your own wonder chemicals in .
For small tanks a Baja style filter funnel will get the crud and water.
Bigger fill volume will need something like a set of Raycor 1000, clamped to the fill hose.
Fill when the fuel dock is not busy , and the extra few min it takes will not be a bother , esp if you tip the fuel hose jockey.
This is the key , all comes from the same pipe .
If you want to be sure of your fuel, filter it for gunk and water as it comes aboard , and pour your own wonder chemicals in .
For small tanks a Baja style filter funnel will get the crud and water.
Bigger fill volume will need something like a set of Raycor 1000, clamped to the fill hose.
Fill when the fuel dock is not busy , and the extra few min it takes will not be a bother , esp if you tip the fuel hose jockey.
Over the years I have heard/read numerous fuel discussions with delivery drivers, refinery chemists and station owners. Additives were added by the driver at the point of supply, which in my case, is from the Colonial pipeline. The fuel pulled from the supply was the same irregardless of Brand and the only difference might be the additive package.
In my truck, I MIGHT pour in an additive if we are going to get REALLY cold and a cold much lower than what we have been getting. Since the fuel supplier is adding anti gel to the diesel they might have only added enough for the recent temperatures and a much lower temperature MIGHT cause a problem. I have never had a problem when I have NOT used an additive.
I often use an additive in my tractor since the fuel can sit for months. The fuel could be bought in the summer and then used deep in the winter so I use an additive. I have used JD, Power Service and one other major brand I can't remember at the moment. I can say the additives have done anything good or bad or prevented anything bad.
Later,
Dan
