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Old 07-04-2016, 04:00   #61
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Re: How Do You Dip Your Tanks?

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Originally Posted by s/v Jedi View Post
Some random points (it's how my brain jumps back and forth

- ever since the beer brewer pipette has been mentioned you got the easiest method to take samples. Don't dismiss those posts thinking it needs to be a glass tube, because it has been posted over and over that a transparent vinyl hose can be used as well.

- there are old ways and new ways to doing things. For fuel pickup the old way was to keep the tube a distance above the bottom of the tank so that dirt wasn't drawn in. The obvious flaws of that plan are 1) you give dirt the chance to accumulate there and 2) you can't use the tank capacity
The new way is to attach a short piece of fuel hose to the end of the pickup tube so that it makes a 90 degree bend and shaped like a "J" picks up from right at the bottom level. Now you can use all fuel and get all dirt and water in the filter where it belongs instead of saving it in the tank
Thanks -- very interesting.

Concerning "new way" and "old way" -- I think the "old way" presumes that you monitor your tank and clean it often enough that the mess at the bottom won't get out of control. If you don't do that, then the "old way" is terrible for the reasons you say.

Whether the "new way" works well or not I don't know. I think I wouldn't be inclined to experiment with something like that.

So I think what I'm going to do is to just try to do the "old way" well. I'll try to do a plastic pipette like has been suggested here. I have my doubts that it will work in my very deep tank, but I'll try.

Failing that, I will try to get a sample by pumping with an outboard pump.

If I find any water or dirt (God forbid), then I'll go back to my professional tank cleaner and have it done properly, which is a real pressure wash of the inside of the tank using fuel at very high pressure, using a wand to direct the jet of fuel to every part of the inside of the tank.

I know some people, like my friend Ken, have been very insistent about just polishing the fuel and forgetting about it, and every time I get such a suggestion I think about it again, but I still think without having a way to be sure that you are really draining off everything at the bottom, this might not do the job, and at the same time tempt you to forgo actual inspections of the tank which in my opinion are absolutely essential no matter what kind of system you have.

What is crucial for a polishing system to really do the job, it seems to me, is that the tank be formed in a way to provide a real pronounced sump, with the pickup for the polishing system drawing straight down from the bottom of that.

In fact I think unless you are at high risk of getting really bad fuel, a drain at the bottom of a sump like that may be all you really need, as the fuel gets polished in any case by the return circulation of the main engine.

Nick, how often do you inspect the insides of your tanks? Do you have any easy way to get inside them?

I have a large inspection hatch, but the single tank is very deep, so I can't see absolutely every part of the inside of it, which bothers me (even though I know that if the sump is clean (which it always is), it is very unlikely that there is any problem elsewhere). My next boat will have inspection hatches, probably multiple in each tank, arranged to make is possible to really get a good look behind every baffle.

I suppose an endoscopic camera could be used . . .


I will admit once more for the record that I am paranoid about this and maybe go a bit overboard. In seven years cruising this part of the world, I have yet to find a single drop of water in either tank or filter, or any dirt in my tank. I typically change Racor filters only every two years because they are never dirty. I like to think that I am lucky with fuel because I work so hard at it, but I realize that this may not be the case . . .

In fact I think my real experience is the result of (a) the good, dry, clean, fresh fuel which is sold in this part of the world, not like Florida or the Caribbean or the Eastern Med); (b) good design of filler and vent systems on my boat, which keeps seawater out of the tank. The rest might really be probably more or less superfluous, but I'm not planning to stop, and my next boat will have a fuel system like yours, Nick, so that I won't have to fear cruising in places with dodgy fuel (or being forced to use biodiesel, if that ever happens).
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Old 07-04-2016, 04:42   #62
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Re: How Do You Dip Your Tanks?

Dockhead,

Using your engine fuel pump, existing fuel pickup and return and existing Racor is nowhere near the same process as fuel polishing. A proper polishing system will circulate the entire contents of your fuel tank in an hour or so. In our case, 3-4 gallons per minute which will also create the flow rate necessary to keep the tank bottom clean. The polishing system also takes up fuel and returns fuel to the very bottom of the tank in opposite corners, unlike your existing fuel system.
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Old 07-04-2016, 04:59   #63
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Re: How Do You Dip Your Tanks?

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Dockhead,

Using your engine fuel pump, existing fuel pickup and return and existing Racor is nowhere near the same process as fuel polishing. A proper polishing system will circulate the entire contents of your fuel tank in an hour or so. In our case, 3-4 gallons per minute which will also create the flow rate necessary to keep the tank bottom clean. The polishing system also takes up fuel and returns fuel to the very bottom of the tank in opposite corners, unlike your existing fuel system.
That sounds like a very good system, especially the cross-circulation across the bottom of the tank and the high flow rate.

Do you actually inspect your tanks to verify that it's working as you presume? If not, I would recommend that you do.
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Old 07-04-2016, 05:17   #64
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Re: How Do You Dip Your Tanks?

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That sounds like a very good system, especially the cross-circulation across the bottom of the tank and the high flow rate.

Do you actually inspect your tanks to verify that it's working as you presume? If not, I would recommend that you do.
Two very large 10-12 inch clear circular covers allow full access and viewing of the entire internal fuel tank. I just need to lift up two easily removable floor boards. It takes less than five seconds along with a torch (flashlight). The same access is provided for the fiberglass water tank.

No fuss, no mystery, no worries.
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Old 07-04-2016, 06:22   #65
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Re: How Do You Dip Your Tanks?

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Originally Posted by Kenomac View Post
Two very large 10-12 inch clear circular covers allow full access and viewing of the entire internal fuel tank. I just need to lift up two easily removable floor boards. It takes less than five seconds along with a torch (flashlight). The same access is provided for the fiberglass water tank.

No fuss, no mystery, no worries.
Excellent design, which I just took note to copy on my next boat. Excellent.

I'll make my inspection hatches tempered glass, I think.


My fuel tank, by contrast, is buried in its own enclosed compartment ahead of the engine room and aft of the companionway. You have to remove the built-in microwave (!) to get to it (although you can see it and measure its temperature for example by taking out a bookshelf, which is easier).

Then you have to reach back into the opening left by the microwave and unbolt the inspection hatch, which has about twenty thousand large bolts in it. It's a couple hours of fairly awkward work to get into it and have a good look around the inside of the tank. Not the best designed feature on my boat.
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Old 07-04-2016, 07:08   #66
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Re: How Do You Dip Your Tanks?

I would not bother with tank cleaning, polish regularly and run a fuel treatment (stops the bug + keeps everything clean)
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Old 07-04-2016, 07:09   #67
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Re: How Do You Dip Your Tanks?

this is what I do with my 4wd (150L tank) that regularly sits for weeks without use
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Old 07-04-2016, 07:09   #68
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Re: How Do You Dip Your Tanks?

Retrofitting an existing tank is obviously a difficult thing but it is amazing that so few manufacturers incorporate a sump. I would think in new construction, it would be cheap and easy.


Luckily about 8 screws to remove a small bulkhead and I can pull my tanks. I know guys with the same boat who just take them up to the car wash, pressure wash them then let them dry before reinstalling. Of course these are a pair of 18 gal tanks.
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Old 07-04-2016, 07:12   #69
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Re: How Do You Dip Your Tanks?

Problem with a drain at the very bottom of a tank is is can be broken, then all your fuel goes into the bilge and of course overboard through the pump.
You can accomplish the same thing with a dip tube, the issue is, having a sump, seems most tanks don't.
I see polishing as one of those things that can't hurt, but I don't see the necessity, unless you get a load of bad fuel, if you did you could clean it.

I'm one who believes the dip tube should be as close to the bottom as possible, that way you suck it out as it gets introduced.
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Old 07-04-2016, 07:13   #70
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Re: How Do You Dip Your Tanks?

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Originally Posted by valhalla360 View Post
Retrofitting an existing tank is obviously a difficult thing but it is amazing that so few manufacturers incorporate a sump. I would think in new construction, it would be cheap and easy.
. . . .
There is an idea, and even a rule somewhere, that you must not have any holes in the bottoms of fuel tanks in boats. Presumably that's to eliminate the risk of a plug coming loose and dumping the contents of your tank into the bilge.

That's why boat tanks don't have proper sumps and proper drains.
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Old 07-04-2016, 07:40   #71
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Re: How Do You Dip Your Tanks?

Another reason to NOT have holes in bottom of tanks might be fire saftey. A fire that burns through a 'bottom of tank component' (like a hose) will then get a tanks worth of diesel to feed it.

I built my tanks with 'bottom of tank' fuel pick-ups and rubber hose. This is the worst arrangement for fire saftey because the tank valves are on (when the engine is running) for significant periods of time.

A future project is to change out the rubber hoses for fire resistant ones and also to rig remote shut-offs to my tank valves (just a pull cable).

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Old 07-04-2016, 09:21   #72
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Re: How Do You Dip Your Tanks?

if you have a sump, there is no difference between seeing what you get out of a drain cock and seeing what you pull up through a sampling tube, apart from the ease of taking the sample. in both cases you just look at it through a glass container.
you have already got a good enough method with the squeeze bulb and the dip tube, i'm struggling to understand why you would want more than this ???
regarding polishing...i don't see that polishing is the answer to all....but I don't see that it hurts??....i don't think it can ever clean up a dirty tank, tried it, didn't work on my tank but it must help maintain fuel quality in a clean tank?? i think there are two different issues here, dirty tank and dirty fuel. with my particular engines with a high return rate the entire tank volume flows though in just a few hours, the fuel is relatively clean but it hasn't cleaned my tank.
i don't know if there is a rule against having a metal drain cock with a latching type handle permanently installed in the bottom of the tank sump to facilitate easy sampling, certainly it is normal on ships, to facilitate manufacturing it is usually actually fitted in the side of the tank a little above the bottom with a tube on the inside which extends to the bottom. there is no added fire risk with this arrangement, though there obviously is with a fuel hose fitted in this manner. I always assumed boat tanks were plumbed from the top because of a wish to use hoses??
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Old 07-04-2016, 09:29   #73
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Re: How Do You Dip Your Tanks?

My two fuel tanks are 200 gallon each, fabricated from aluminium with sumps that collect all the dirt. Codes prevented Dashew from making a drain valve there, so he had a 1.25" threaded aluminium bushing welded in the bottom of the sumps, and put an aluminium plug in them, which is allowed.

So for me it was as simple as removing those plugs and using an electrically insulating thread locker to put a brass elbow and reducer to 1/2" in there, followed by Parker fuel valves, 3/8" hose barbs and fuel hose that connects to my "transfer manifold" as shown in the diagram. That transfer manifold has a valve on each connection and one of the connections is the actual drain valve.

Between the fuel in the tank and it coming from that drain, there are three valves of which at least two are normally closed.

I need to look through the fuel deck fill to check the inside of the tanks. If suspicious, I need to remove deck plates and tank level sensors to get a better look. I had a little sludge when I bought Jedi. After the first time I drained the sump and polished my fuel, the bottom looked shiny again. Note that corrosion is the culprit here, not a little dirt.

My fuel polishing uses the tap in the sump to draw fuel from and the regular fuel return lines to put it back. It works perfectly.

Here is my old blog post about it: A new fuel system for Jedi (English) - s/v Jedi
OMG it is from 10 years ago already!
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Old 07-04-2016, 09:36   #74
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Re: How Do You Dip Your Tanks?

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Originally Posted by stone beach View Post
if you have a sump, there is no difference between seeing what you get out of a drain cock and seeing what you pull up through a sampling tube, apart from the ease of taking the sample. in both cases you just look at it through a glass container.
you have already got a good enough method with the squeeze bulb and the dip tube, i'm struggling to understand why you would want more than this ???
regarding polishing...i don't see that polishing is the answer to all....but I don't see that it hurts??....i don't think it can ever clean up a dirty tank, tried it, didn't work on my tank but it must help maintain fuel quality in a clean tank?? i think there are two different issues here, dirty tank and dirty fuel. with my particular engines with a high return rate the entire tank volume flows though in just a few hours, the fuel is relatively clean but it hasn't cleaned my tank.
i don't know if there is a rule against having a metal drain cock with a latching type handle permanently installed in the bottom of the tank sump to facilitate easy sampling, certainly it is normal on ships, to facilitate manufacturing it is usually actually fitted in the side of the tank a little above the bottom with a tube on the inside which extends to the bottom. there is no added fire risk with this arrangement, though there obviously is with a fuel hose fitted in this manner. I always assumed boat tanks were plumbed from the top because of a wish to use hoses??
I understand the way you look at things, but here is what is different from my pov: fuel polishing using fixed installations like some of us recommend here, are not for fixing problems with dirty tanks... they are for preventing that situation.

To start clean I suggest shock treatment with enzyme based Startron. Follow it up with a couple gallons of clean fuel to mix it through, then run the engine, genset, heater and every other fuel consumer so that the product gets everywhere and give it a couple days. In the filter bowls you will see the color changing, as well as inside the tank. Then circulate it some more, then burn it in the engine. The enzymes brake the dirt, bacteria and water water down and suspend it in the fuel so that it will pass the filters and burn in the engine.

Once clean, regular polishing keeps it that way. Also, when we stop using the engines for a while, i.e. not using up the fuel, then I add maintenance doses of Startron.
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Old 07-04-2016, 09:44   #75
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Re: How Do You Dip Your Tanks?

Quote:
Originally Posted by stone beach View Post
if you have a sump, there is no difference between seeing what you get out of a drain cock and seeing what you pull up through a sampling tube, apart from the ease of taking the sample. in both cases you just look at it through a glass container.
you have already got a good enough method with the squeeze bulb and the dip tube, i'm struggling to understand why you would want more than this ???
regarding polishing...i don't see that polishing is the answer to all....but I don't see that it hurts??....i don't think it can ever clean up a dirty tank, tried it, didn't work on my tank but it must help maintain fuel quality in a clean tank?? i think there are two different issues here, dirty tank and dirty fuel. with my particular engines with a high return rate the entire tank volume flows though in just a few hours, the fuel is relatively clean but it hasn't cleaned my tank.
i don't know if there is a rule against having a metal drain cock with a latching type handle permanently installed in the bottom of the tank sump to facilitate easy sampling, certainly it is normal on ships, to facilitate manufacturing it is usually actually fitted in the side of the tank a little above the bottom with a tube on the inside which extends to the bottom. there is no added fire risk with this arrangement, though there obviously is with a fuel hose fitted in this manner. I always assumed boat tanks were plumbed from the top because of a wish to use hoses??
The other difference between sampling through a tube, and draining from the bottom, is that you will definitely not get everything out through the tube, which will still be slightly higher than the bottom of the tank. With a drain, you can really get the dregs, which is your goal.


I would not use rubber hoses below the gravity flow level of the main tanks. For safety, I would draw fuel only up from the main tanks, and into a day tank, so that nothing could accidentally drain the main tanks. I would pay attention to siphon risks, too.

Actually, I think the siphon risk is rarely thought about. It certainly exists on my boat. If one of the rubber fuel hoses in my engine room were breached with the tank full, at one of their low points, about half the tank would drain out. I don't know how to manage this, but a qualified engineer should think about it.

I think Jedi's sumps have normally closed valves at the bottom, so I think that's a manageable risk. I think even rubber hoses would be ok, if they are open to the tanks only for short periods when you're polishing or sampling and will have your eye on what is going on.
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