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Old 11-09-2014, 06:40 AM   #21
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>They live,breed,crap,and die and that combination is what builds up and clogs your system.<

BUT,, the Bad part is their bodies and poop stick to and coat the tank walls , until a bit of big motion breaks the junk loose .

With luck it just plugs the filters and you switch over , with less luck it plugs the feed line.YRMV

The best way to solve the problem is with a genuine marine fuel tank, not a cheap box that holds fuel.

A real fuel tank will have a sump that is easy to drain.

Second best is a powered centrifugal filter and DP gauge (differential pressure) that tells when to service the filter.
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Old 11-09-2014, 09:42 AM   #22
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>They live,breed,crap,and die and that combination is what builds up and clogs your system.<

BUT,, the Bad part is their bodies and poop stick to and coat the tank walls , until a bit of big motion breaks the junk loose .

With luck it just plugs the filters and you switch over , with less luck it plugs the feed line.YRMV

The best way to solve the problem is with a genuine marine fuel tank, not a cheap box that holds fuel.

A real fuel tank will have a sump that is easy to drain.

Second best is a powered centrifugal filter and DP gauge (differential pressure) that tells when to service the filter.
FF, we are on the same page..... I still reallllllly like the idea of a day tank. That way the initial filtering is not immediately needed by the engine thereby if there are problems, as a general rule, there is a window of time available to remedy. You are not shuffling filters, mechanicanining underweigh. I am extremely afraid of my engine room with the main running in my "new"old boat. The unguarded v belt hydrolic pump off the main is frightening. It would eat you alive.

I am looking at this and stroking my chin. Really, were I installing a stern thruster I would have done an electric pump, but it has a v belt take off the main, it is what it is for now.

How right you are about a box holding fuel. Bottom bleed is good. 3/4" ports to get a polisher probe in to hi pressure fuel blast in each baffle for polishing are other good ideas.
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Old 11-09-2014, 10:57 AM   #23
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Instead of simply moving to the equator in winter, why not become a full time Arctic Tern researcher and go pole to pole and back once a year? Enjoy an Arctic summer during breeding season, then head south for a lovely Antarctic summer in the Weddell Sea, then back to the Arctic for summer, etc...

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Old 11-09-2014, 01:37 PM   #24
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Compass Marine, Yacht Survey Online, and I believe the condensation issue is largely a myth.

I have read articles that support both sides of the fence, but my practice experience supports the camp that thinks minuscule amounts of condensation form in the average boat fuel tank over the winter.

Some insurance companies have required some marinas to require filing tanks as a safety issue in case of a yard fire (partially full tanks are more dangerous). With ethanol fuel, there are some very good arguments against filling tanks in case of phase separation.

http://www.pbase.com/mainecruising/f...t_condensation
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Old 11-09-2014, 01:46 PM   #25
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I too really doubt the condensation issue really exists. I keep my tanks at low level most of the time to save weight, and have never had a drop of water in either the tank or the racor. 8yr and 2000hr. Not a drop. NC also has some serious temp/humidity swings, especially in spring and fall.

But the tank fills are under the deck hatch. And the vents go through a custom made liquid separator.

I suspect most of the water in tanks comes from leaky deck fills exposed to sea spray and weather, and poorly done vents.

Aircraft are different as the tanks get some serious temp swings with altitude changes, and tank skin usually is directly in contact with the air stream. Big temp swings. Not so much on a boat.
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Old 11-09-2014, 04:22 PM   #26
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Condensation in fuel tanks is very dependent on a lot more factors than just air temps.
As a couple of you point out the size of the tank and the exposure of the tank can influence condensation issues. I think aircraft and highway trucks and probably underground tanks are much more at risk than boat tanks.
On my boat tanks the pickup points on the 4 big storage tanks are at the lowest point of the tank so any water would end up in the filter. I think design and maintenance are much more important than if the tank if full over the winter or not. Good maintenance practices can make up for a lot of design shortfalls. Poor maintenance can, of course, defeat the best designs.
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Old 11-09-2014, 06:04 PM   #27
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My reason for pointing out the condensation issue is a lot of boating mag writers have been passing this info along for years and I have proven it to myself and have read the same opinion from other real world pros.

I think it does happen but is an urban myth for most boat tanks and all boat owners should have "the rest of the story".
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Old 11-09-2014, 06:13 PM   #28
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After building new tanks (90 gal. Total) for Panope, the boat remained inactive (on the hard) for 12 years. During this period, I used a single, 50 gallon batch of diesel to occasionally power the furnace during winter construction. The fuel remained perfectly clean and usable.

The tanks have never been full. Not a drop of water or debris has ever been found. The tanks vent directly to atmosphere (western Washington atmosphere). The fuel flows from fittings located at the extereme (V - shaped) low point of the tanks. My gut feeling is that the fuel would have been good for at least another 50 years.

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Old 11-09-2014, 06:19 PM   #29
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After building new tanks (90 gal. Total) for Panope, the boat remained inactive (on the hard) for 12 years. During this period, I used a single, 50 gallon batch of diesel to occasionally power the furnace during winter construction. The fuel remained perfectly clean and usable.

The tanks have never been full. Not a drop of water or debris has ever been found. The tanks vent directly to atmosphere (western Washington atmosphere). The fuel flows from fittings located at the extereme (V - shaped) low point of the tanks. My gut feeling is that the fuel would have been good for at least another 50 years.

Steve
Thanks...more proof dispelling a huge urban myth perpetuated by articles written by people who must research their articles by reading other boating mag articles.
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Old 11-09-2014, 06:25 PM   #30
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In my experience, limited as it may be, I've never seen algae in a fuel tank, or any bugs for that matter. I have seen lots of aspertines (ashaltenes sp?) in fuel tanks and plenty of just plane old nasty sticky crud in the bottom. And lots of really clean clear looks drinkable water, even in tanks with nice red diesel. But, one big dose of that clean water (rough sea) and you are done. Tank access is still the best way to circumvent that. A sump is really good.
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Old 11-09-2014, 06:28 PM   #31
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Where I've seen condensation is not in the boat, but in the marina. In some areas, low volume marinas decide to not spend the money before the winter. No when you're talking about an underground tank which holds 10,000 to 50,000 or more gallons of gas it's a very different situation. Even then properly watched it won't be a problem. I use to watch the marina I frequented measure the water in their tanks. Often it would be four to six inches. But their pickup was a foot from the bottom.

In boats themselves, it's always been other problems with their fuel that I've seen over the winter, not condensation.
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Old 11-09-2014, 06:54 PM   #32
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" I use to watch the marina I frequented measure the water in their tanks. Often it would be four to six inches. But their pickup was a foot from the bottom. "

I hope to not fuel in a place like that just after they have had a delivery from the truck and stirred all the water in the bottom of their tank into all of the fuel in the tank.
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Old 11-09-2014, 07:05 PM   #33
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Probably more common than we all wish.
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Old 11-09-2014, 08:32 PM   #34
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I too really doubt the condensation issue really exists. I keep my tanks at low level most of the time to save weight, and have never had a drop of water in either the tank or the racor. 8yr and 2000hr. Not a drop. NC also has some serious temp/humidity swings, especially in spring and fall.

But the tank fills are under the deck hatch. And the vents go through a custom made liquid separator.

I suspect most of the water in tanks comes from leaky deck fills exposed to sea spray and weather, and poorly done vents.

Aircraft are different as the tanks get some serious temp swings with altitude changes, and tank skin usually is directly in contact with the air stream. Big temp swings. Not so much on a boat.
After 12,000 gallons or so of fuel the amount of water I have drained from my Racors is none, as in zero. The tanks are never more than half full, as I buy fuel a thousand gallons at a time, and by the time winter comes, they are frequently only 1/4 full. The initial load of fuel on the boat when I bought her was 4 years old when our refit was done, and while I polished out a bit of black stuff and noticed that the engine smoked a tiny bit more burning that fuel than fresh, there was no discernible difference between fresh fuel and stuff 4 years old in terms of performance. I replace the polishing filters for drill each year and this year there was no more than a teaspoon of black deposits on the filters, even though I polish when the tanks only have 75 gallons or so when sloshing around in a seaway. In other words, there is no moisture, no crud, nothing in these tanks. I opened the drain at the bottom of the wing tanks, also for drill and all that comes out is clean fuel.

Many myths are just that. Myths. However, if your fuel source has water, so will you. I don't because our fuel comes from the refinery 5 miles away, with natural tank condensation contributing nothing in that regard.
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Old 11-09-2014, 09:39 PM   #35
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" I use to watch the marina I frequented measure the water in their tanks. Often it would be four to six inches. But their pickup was a foot from the bottom. "

I hope to not fuel in a place like that just after they have had a delivery from the truck and stirred all the water in the bottom of their tank into all of the fuel in the tank.
That's one of the safe marinas. It's very common for underwater gas tanks to have some water. That's why checking them is important. Gas stations also monitor theirs, or the good ones do.
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Old 11-09-2014, 10:13 PM   #36
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I think the fuel quality in the SE USA is poor. I think the fuel quality in the NW USA (and Canada) is good. And that is the crux of the problem. It probably has something to do with the either the choice of cat cracking or hydro cracking and the feedstock to the refinery in the areas.

Condensation in some storage tanks is real; condensation in my boats fuel tanks is not. I suppose that hot fuel with water held in suspension will precipitate out when temperature drops, and that might be a factor in the SE fuels due to climate. I saw the compass marine trial. I thought he was daring to suggest a counterargument, but I think he is right, at least for his weather conditions.

I did have asphaltene precipitation in my old fuel when I first purchased the boat. Filter took care of it.
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Old 11-10-2014, 03:29 AM   #37
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I was told to read the MDS sheets for diesel and you will see that all diesel has some water in it from the refinery. I haven't for a long time so I do not have numbers. Add in the transfer from the tanks, pipelines, trucks etc. and you have water content. If you keep it moving or stirred it will stay in suspension and be burnt or under the correct circumstances it will support the growth of organisms.

Spinning filters take care of any present.

Measure the size of your fuel tanks, then find out how much moisture can be supported by that volume of air at winter temperatures in the tank, assuming very little air circulation and figure out for yourselves how much water will condense out of that air. Minuscule amount.
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Old 11-10-2014, 06:45 AM   #38
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it's not always a good idea to have your engine return fuel to the main storage tank. Food for though.
Where else can it go?

In Canada the law requires that diesel be returned to the tank from which it was drawn.
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Old 11-10-2014, 08:34 AM   #39
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MSDS, material safety data sheet. I've never looked at one for diesel, interesting.
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Old 11-10-2014, 12:22 PM   #40
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Where else can it go?

In Canada the law requires that diesel be returned to the tank from which it was drawn.
We return fuel to the tank the engines are drawing from to ensure that we don't overflow a tank, but I'm curious what the reason is for making it a law to return fuel the main tank? How does the law define main tank?
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