Getting water out of the diesel tank

[Tenedos]

Ahoy sailors,

On my boat, fuel and water inlets are right next to each other. I think you already guessed what happened but basically while trying to fill the water tanks at dark, I accidentally put fresh water into an already full 20 gallon diesel tank. Until I noticed my stupid mistake, about 2 gallons of water has already found its way into the tank...

I have been searching and reading through similar questions and suggestions. I get that the water is heaver than diesel so went straight to the bottom of the tank. I also understand the main recommendation is to drain the tank, however my tank doesn't have a drain at the bottom, nor does it have an inspection port. It is basically this tank without the inspection port on it:



Here is what I did:

• I obviously didn't run the engine.
• I disconnected the hose that goes into the fuel filter and started emptying the tank. After a tiny bit of diesel which was probably sitting in the hose, clear water started pouring out. I collected about 2 gallons of water until pure diesel started coming out of the hose again. I let it out a bit to make sure no more water was coming, then I re-connected the hose back to the fuel filter.

Now I understand that the fuel outlet doesn't probably reach all the way to the bottom of the tank so there may be some water left there. Unfortunately, I have no good way of verifying that. I am *assuming* in normal conditions it is fine, as it won't get into the engine but when I take my boat and it starts rocking on the waves, I am not sure if that water may find its way into the engine.

So I am looking for recommendations.

• Would the water in the tank have caused any problem until I took it out (it sat there less than 48 hours until I figured what to do and found time from my work to do it)?
  
• Should I try to dump all the diesel by continuing the above mentioned method? I don't mind dumping it but logistics of it is the difficult part (where to dump the fuel etc). So wondering if it would be safe or stupid to keep it there?
  
• Any additives or anything similar I can use to help somehow?
  
• I haven't changed the fuel filter yet but I certainly will. I am thinking of at least trying to start the engine before doing that, would that be wise?
  
• I ordered a USB endoscope and I will try to push it into the tank if I can empty it completely to see what may be happening but again, emptying the tank is a bit of a challenge. I will do it if necessary but want to get recommendations.

Thank you in advance,

Tenedos

[Pizzazz]

Most likely you have some small amount of water left at the bottom of the tank. One approach is just not to worry about it - not optimal since when the boat is sailing in waves the water will splash around and will find its way to the engine. A better way is to suck this water out with a hand pump. You can use a primer pump for outboards, a child's water toy pump or something similar. Attach a small hose to the pump (I use 1/4") then disconnect the tank fill hose and dip the small hose all the way to the bottom. Make sure it is not bent and feed it to all the edges of the tank. Suck out as much of the water as you can. Then it should be OK.

[Lepke]

Not too dissimilar to people with contamination problems. If you have a good fuel system, like a Racor primary and engine secondary you can clean out the water by operating. Use a good fuel conditioner at a high rate about 3x normal. It will help the Racor separate out the water in addition to killing any organisms and removing sludge over time. Better conditioners also help fuel burn so no loss in power.
Another method is to add an electric fuel pump and circulate thru the primary at the dock until no or little water is showing up in the filter bowl.
Keep an eye on the primary. Best if you have a vacuum gauge after the filter to show plugging. Released sludge will show up as small or tiny particles caught by the primary. I have never actually plugged a 30 micron primary or 10 secondary with this method including 500+ gallon, dirty tanks. A good secondary can hold up to an ounce of water, too. Any rare water that gets by the primary should be caught in the secondary. If yours is drainable, check it.

[Pete7]

Could have been worse, you might have put diesel in a water tank, now that is a real disaster.

Why not put an inspection hatch in the tank because you know you are going to want to see inside the tank occasionally.

https://www.google.co.uk/search?q=he...w=1152&bih=616

[Tenedos]

Originally Posted by Lepke

Not too dissimilar to people with contamination problems. If you have a good fuel system, like a Racor primary and engine secondary you can clean out the water by operating. Use a good fuel conditioner at a high rate about 3x normal.

Thank you. That is what I have indeed. What fuel conditioner would you recommend?

[Tenedos]

Originally Posted by Pete7

Could have been worse, you might have put diesel in a water tank, now that is a real disaster.

Why not put an inspection hatch in the tank because you know you are going to want to see inside the tank occasionally.

https://www.google.co.uk/search?q=he...w=1152&bih=616

Thank you. I did some reading about it and at least according to Catalina Direct, a hatch needs to be USCG approved. No idea where it is coming from, I am afraid to cause problems than the ones that I solve.

Henderson hatch looks interesting. Being plastic, does it work ok on an aluminum tank?

[Tenedos]

Originally Posted by Pizzazz

A better way is to suck this water out with a hand pump. You can use a primer pump for outboards, a child's water toy pump or something similar. Attach a small hose to the pump (I use 1/4") then disconnect the tank fill hose and dip the small hose all the way to the bottom.

Thank you for the suggestion. I will try this tomorrow, hope it works.

[masonc]

I've been dealing with a lot of watery in diesel latelybecause of Irma. Our truck had about three gallons in the fuel tank, and a rental generator had about a gallon. A lot of the problems come from high humidity in hurricanes.
I bought a small 12v fuel pump, put alligator clips and leads on it, and some clear 1/4 inch vinyl tubing. I shoved the tubing to the bottom of the tank and pumped the water out into a white bucket. Clear tubing let's you see when you hit a pocket of water.
The diesel in the truck was beyond redemption, had to dump 30 gallons.

[Pete7]

Originally Posted by Tenedos

Thank you. I did some reading about it and at least according to Catalina Direct, a hatch needs to be USCG approved. No idea where it is coming from, I am afraid to cause problems than the ones that I solve.

Henderson hatch looks interesting. Being plastic, does it work ok on an aluminum tank?

Haven't fitted one to an aluminium tank, but several to stainless steel tanks. The only aluminium tank I had was full of pin holes so replaced with a flexible tank and sold the boat.

Henderson hatches are made by Munster Simms near Belfast who also make Whale pumps. You could always ask them about USCG certification, but they are standard fit by tank manufacturers in the UK.

https://www.whalepumps.com/contact-us.aspx

Pete

[Steve Bean]

Sorry I don't have a reliable solution, but a caution about the idea of pushing a hose to the bottom of the tank and pumping the water out. Without X-ray vision, how can one know where the end of the hose is? I would suggest multiple tries with different tubes of different stiffness and size, and whatever techniques you can think of to get the end in different positions. When you get tired of this, I would suggest partially filling with fuel and wherever additive you choose, to allow room for sloshing, and motor sailing out to some rough water, with a plan in place in case of engine stoppage.

[GordMay]

Henderson’s Bolt on retro-fit access hatch is suitable for diesel or water tanks. ➥ Access Panels|tank|hatch|boat|water|TCL4

[skipmac]

Are all the fittings on the top of the tank welded on like the photo? On my tank the fuel gauge unit is screwed on so I could remove that to use like a very small inspection port. To get the water (and sludge) out of my tank I got a drill operated pump, attached a piece of flexible hose. Attached the hose to a short, semi flexible rod with tie wraps with about 2" of hose extending beyond the stick.

With this I was able to direct the hose into the lowest section of my tank and suck out all the water. It helps if you can do this when the boat has been sitting still and not rocking around for a day or so (and still while you're doing this) so all the water will settle and sit in the low part of the tank.

FYI, unless your tank has a small sump on the bottom for the pickup, the regular fuel pickup line will be higher than the bottom of the tank to avoid clogging the pickup with any small trash that might make it into the tank so there is definitely some water left. I would be a bit nervous about trying to get that bit out by sailing and using the boat for fear that a large slug might come in at the worst moment and leave me without an engine at a crucial moment.

[S/V New Sensation]

I added access panels to my fuel tanks to reach areas I couldn't from the original access panels. I used the SeaBuilt Access Plate System. I had bad luck with the plastic access plates on a previous boats water tank. I've had the plates in place for over ten years and no leaks. More effort to open because of the bolts but still pretty darn easy and now I can access all areas of my tank to inspect and clean.

[donradcliffe]

Been there, done that. I did what the OP did--pump out of the tank until I got pure diesel again. Then started the engine, and kept a close eye on the bowl of the Racor filter, which is where the water will end up next. First motored at the dock, then for brief periods out in some small waves. I turned off the engine and drained the Racor bowl when i saw an inch of water. It took about 4 cycles of bowl draining before I got it all.

[hellosailor]

Plan on fuel polishing and replacing filters several times, to be on the safe side. The unanswered question is what will the water do long term. It will cause biomatter to grow at the water/fuel interface. More "bugs" (algae, bacteria, whatever the correct scientific term for "crud" is) to grow, more need to clean the filters and the tank. The longer it sits, the more likely you'd need to clean the whole tank, so it should come out sooner rather than later.

I'd agree that doing the hard job--adding in an inspection port--will pay off in the long run, because sooner or later all diesel tanks can use hands & eyes inside them.

For those of us who somehow missed the "How to Be Care Free" classes in grade school...it is a wonderful feeling to KNOW that the inside of the diesel tank is spotless and the ***damn thing will have no reason to spit or cough all season long.