Surprised at the fuel dock

Not by the price. I have four fuel tanks and use the two forward 250 gallon tanks regularly. The two aft 100 gallon tanks are used for trim purposes, one half full and the other empty. But I am getting ready for a long trip north and decided to fill the aft tanks. As I started to fill the empty aft tank, fuel pump hose shut off automatically almost immediately. To my shock, the tank was full of water! The deck fill is tight, good caulking around the deck fitting, a new o-ring, no water on the top of the tank in the ER. The tank vent is well above the water level. I am the only person that fills the tanks and did not mistake it for the water tank fill on the bow. Can anyone come up with an explanation besides vandalism? Thankfully I have a fuel manifold and have the tank isolated, and plan to dry it out next week.

Hard to imagine rain water getting in there any way. Unless...you have some rust holes on the top that could allow rain that could get in and drip down onto the top, (rather like happens with the old CHB teak deck leaks and rusted out tank tops), then seep into it over time. However, even then significant water getting in is seldom reported, but those are usually main tanks in regular use, so the water would not have the time to accumulate in large amounts before being sucked out into the filter separators. However, these are tanks that by your description of use, sit untended for long periods, so is that possible..? Because, if not, it would appear someone would have had to open the deck fill and put it in there. If so, very disturbing, but lucky not a main tank.

Peter B said:

If so, very disturbing, but lucky not a main tank.

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My feelings exactly. The boat is only 5 years old. When I bought the boat three years ago, I polished the fuel in the aft tanks and transferred it to the forward tanks, so sometime in the last three years doesn't narrow it down much.

I would seriously consider the possibility of vandalism. We've had some of that in our area.

On what basis did you determine the full tank to be empty? Maybe you bought it that way.

sunchaser said:

On what basis did you determine the full tank to be empty? Maybe you bought it that way.

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See his second post, No 3...

I believe you can rule out a surface leak. 100 gallons takes about 10 minutes to fill using a garden hose! Even vandalism would take a really determined effort, although entirely possible. This is a head scratcher for sure.

dimer2 said:

I believe you can rule out a surface leak. 100 gallons takes about 10 minutes to fill using a garden hose! Even vandalism would take a really determined effort, although entirely possible. This is a head scratcher for sure.

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He hadn't checked the tank for 3 years Blue. A slow trickle each time it rained could add quite a lot over that time frame.

drb1025 said:

My feelings exactly. The boat is only 5 years old. When I bought the boat three years ago, I polished the fuel in the aft tanks and transferred it to the forward tanks, so sometime in the last three years doesn't narrow it down much.

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Following on from above...which tank filled with water drb..? The one you left half full for trim, or the one you left empty..?

Is it possible that when fueling up you asked one of the attendants to fill your water tanks also?
I dont let anyone ever fill my tanks without me watching - or pump out my septic.

Greetings,
Mr. drb. Good you caught it. Since you don't really have any evidence of exactly what happened I'd put it down to "who knows?" and keep a close eye on the situation.

Report it to the marina authorities and move on. Could be vandalism or a mistake sometime in the past. As I said, who knows?

Pete, a normal water hose puts out around 5 gal/min...it would take 20 minutes to fill.

If there was a gaping 1" square hole in the top of the tank, how many inches of rainfall would it take to fill the 23,100 cubic inch tank? Even in WA, this is unlikely IMO...but it's a boat, anything is possible

Is the tank molded into the hull or freestanding? What material is it made of? How is it vented? Is it entirely above or below the waterline?

100 gallons is a lot of water. Unless there is a leak out to the sea this doesn't make sense. By the way, I think we are all assuming this is fresh water. Is that correct?

To narrow things downs:
- Is it freshwater or seawater?
- If freshwater, you may be able to test if it's tap water or rain water: https://www.simplexhealth.co.uk/identify-source-of-a-water-leak-in-your-property-cms-52.html

caltexflanc said:

Is the tank molded into the hull or freestanding? What material is it made of? How is it vented? Is it entirely above or below the waterline?

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Both aft tanks are free standing steel tanks vented out the top to the side of the hull and are partially below the water line.

Bay Pelican said:

100 gallons is a lot of water. Unless there is a leak out to the sea this doesn't make sense. By the way, I think we are all assuming this is fresh water. Is that correct?

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I returned to the dock and haven't tested it yet. I'll be taking care of this next week.

I appreciate the comments, and if I find out how it got in there, I will report back. I will report it to the marina office too.

Peter B said:

See his second post, No 3...

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And this is what got my attention.

DFs normally have very nice sight tubes. If filled with water it may well have appeared empty and therefore was never visually a candidate for transfer to the forward tanks. We do know it was deemed empty, so how?

I sure can't remember what tank contents I moved where from three years ago on my DF. BTW, I put red duct tape on my fuel fills and leave it there. DFs have very confusing deck fill locations, 7 of them.

sunchaser said:

And this is what got my attention.



DFs normally have very nice sight tubes. If filled with water it may well have appeared empty and therefore was never visually a candidate for transfer to the forward tanks. We do know it was deemed empty, so how?



I sure can't remember what tank contents I moved where from three years ago on my DF.

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Yes the tank has a sight tube and it was clear, leading me to believe it was empty and later to assume the content is water. Does red dye fade out of fuel in closed sight tubes? I will sample the tank today or tomorrow.

I have purchased lots of non dyed marine fuel in the PNW. BC vs WA vs AK vs tribal accounts for the variance. The coloring of the non dyed is yellowish on my sight tubes at times, never seen clear like water.

I assume your aft tanks have drain valves located on the sloped bottom? These are what are used to completely empty the DF aft tanks.

So the only check has been looking at the sight tube? Was there definitely liquid in there?

First confirm it is water and not undyed fuel, which can be pretty clear in a sight tube.

Also look at the deck fill. Is it in a position where rain and/or runoff can contact the cap? Some designs are such that even with a bad oring it is pretty impossible for water to get in. Other designs have water on top of them routinely and absolutely count on the oring to seal. which is yours?

Xlantic said:

To narrow things downs:
- Is it freshwater or seawater?

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This is what I was wondering as well....

Ski in NC said:

First confirm it is water and not undyed fuel, which can be pretty clear in a sight tube.

Also look at the deck fill. Is it in a position where rain and/or runoff can contact the cap? Some designs are such that even with a bad oring it is pretty impossible for water to get in. Other designs have water on top of them routinely and absolutely count on the oring to seal. which is yours?

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I'm going to the boat today to pull a sample of the mystery fluid. The deck fill is under the covered side deck so not directly in the rain. I replaced all four o-rings last year.

If fresh water, check with swimming pool test kit for presence of chlorine. Rain water will have none.

I vote for fuel.
Just seems more likely it's had fuel in there the whole time.

And hope so to.

Kolor Kut is a water finding past. Put some on a stick or 1/4" flexible copper line.
http://www.amazon.com/Kolor-Kut-Ounce-Water-Finding/dp/B00905UC5E
Easy test. I used it in my above ground oil tank, since removed.


Jim
Sent from my iPad using Trawler Forum

Post#21
Second reason it is full, fuel shutoff while fueling.

caltexflanc said:

So the only check has been looking at the sight tube? Was there definitely liquid in there?

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Maybe it's empty, and the vent lines are kinked?

I pulled some mystery fluid from the tank and it appears to be diesel fuel. Here are two pics, the first is the site tube after putting in a few gallons at the dock then realizing it was full. You can see how it isn't red. The second is today after opening the site tube valves, now red top to bottom.


Apparently the dye faded in the site tube and I forgot I had filled it three years ago. No excuse for that.