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Old 06-01-2015, 16:37   #1
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Measuring Water in Fuel Tank

Our boat has been on the hard for a few months. When it was stored the bow was sitting a bit low, and this allowed water to pool on the side decks about an inch deep. The water was sitting on top of the diesel fill deck plate, and a good amount of water ended up leaking into the tank.

We ended up pumping out about 16 gallons of water in the end. Before we started pumping, we used a product that a neighboring boat had, that allowed us to measure the amount of water in the tank. It is a paste that we smeared onto a metal measuring tape and then dipped into the tank via an inspection plate. The paste turns red where there is water, and showed us that we had the bottom 11" of tank filled with water (see photo). By our tank chart that figured at about 17 gallons. After pumping the tanks we used the paste again to check for any remaining water (got just a small touch of red on very tip of probe).

The paste had been picked up from a home heating oil distributor, who uses this to check for water in heating oil tanks. Works with Diesel, gasoline and oils.
Stuff is called "Kolor Kut Water Finding Paste".

Anyway, thought others might find this a useful product. Great for checking fuel tank for water.
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Old 06-01-2015, 17:22   #2
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Re: Measuring Water in Fuel Tank

I just use a clear tube. Dip it in the tank then put your thumb on the end. The water is clearly visible. You can also see any slime on the end of the tube.

It pays to polish your fuel and physically inspect your tanks regularly.

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Old 06-01-2015, 17:31   #3
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Re: Measuring Water in Fuel Tank

Measure? If I read the post correctly you have a small (By most standards) tank . Please... suck out every bit and clean the tank. if you have a wash out plate open it and scrub the crap off the sides if you can.
With that much water in the tank any attempt to perc the water off just ignores the issues of algae etc.
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Old 06-01-2015, 18:07   #4
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Re: Measuring Water in Fuel Tank

+ another one for completely emptying the tank and cleaning it as best you can. Better a big job where and when you plan it rather than under way.
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Old 06-01-2015, 18:14   #5
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Re: Measuring Water in Fuel Tank

Thanks for the tip! Have not heard of that stuff before.
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Old 06-01-2015, 18:41   #6
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Re: Measuring Water in Fuel Tank

I hope you replaced the o-ring on your deck filler cap as well.
Any amount of water in the fuel can be a disaster at sea. It doesn't take much to destroy your injector pump.
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Old 07-01-2015, 10:07   #7
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Re: Measuring Water in Fuel Tank

That looks like some pretty cool stuff. I may try it. My present technique is to take a stiff tube and pump out about 1/2 liter from the lower corners of my tank, into a clear bottle. Let it sit and you can see if there is any water. This also allows me to see if the fuel itself is getting a little cloudy, maybe algae or bacteria. If there is any water I pump the lower reaches until I'm pretty sure none is left. I do this at the start of every season and I don't start my engine until I'm sure all is OK.

Shortly after I bought my boat I had a plug of algae catch in my intake for the fuel line and stop the fuel flow which killed the engine. I was in a channel leaving the intercoastal and fortunately we had the main up so we could just sail out into the ocean. That one cost me about $400 to have a "fuel specialist" come out and pump out about 9 gallons of really rotten fuel and "clean" my tank. Since then I've been pretty careful but have completely emptied my tank twice and really cleaned it out well. I've only got a small port so it's a bit of work to clean it but well worth the peace of mind.

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Old 08-01-2015, 06:16   #8
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Re: Measuring Water in Fuel Tank

Agree with Kokanee, the wAter will again find its way into the tank if you fix the problem

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fuel, fuel tank, water

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