Water filled Keel tanks?

[LeoKa]

You can open them from outside perfectly well if you don't mind the expense of welding it back together after. If these are tanks and not concrete ballast as I would have suspected you'll want a good look inside after the time they've gone uninspected. On steel commercial boats I've owned the ballast tanks are opened annually for inspection and cleaning, fuel and freshwater as well.

I bought the boat less then a year ago. I don't think those tanks were ever opened. The original builder decided to flood them (water or oil?) and use them as ballast. The boat has 4 tanks. Each 400 gallons. The PO only used the side tanks in the ER (2 x 400 g ). I want to use the keel tanks again for fuel.

I do not want to open them from below. I just want to use some kind of scope or camera to look inside as much as possible through the pipes.

 

[Fish53]

I bought the boat less then a year ago. I don't think those tanks were ever opened. The original builder decided to flood them (water or oil?) and use them as ballast. The boat has 4 tanks. Each 400 gallons. The PO only used the side tanks in the ER (2 x 400 g ). I want to use the keel tanks again for fuel.

I do not want to open them from below. I just want to use some kind of scope or camera to look inside as much as possible through the pipes.

Have you considered contacting a marine surveyor, one that's experienced with steel hulls?

 

[LeoKa]

Have you considered contacting a marine surveyor, one that's experienced with steel hulls?

NO. I don't need to survey the tanks or the hull. Everything is fine.

I just want to know, which pipe shall I open?

 

[Lepke]

Harbor Freight sells a flexible fiber optic viewer for peering into tight places. It may have a long enough cable to view the tanks.
If the tanks were filled with water and are rusty and you don't want to sandblast, I use a product: Archoil AR5100. 1 oz/gallon. Dissolves only rust, leaves metal looking like it was sandblasted. Probably could be added to existing water before it's pumped out.

 

[LeoKa]

I use a product: Archoil AR5100. 1 oz/gallon. Dissolves only rust, leaves metal looking like it was sandblasted. Probably could be added to existing water before it's pumped out.

Wow, this looks great! Thanks Lepke.
It could really simplify what I am trying to accomplish.

 

[LeoKa]

Dissolves only rust, leaves metal looking like it was sandblasted. Probably could be added to existing water before it's pumped out.

Finally I have got to it and opened the pipes to the tanks.
First, there were not completely full. Actually, the level was way low. At first dip, the liquid inside seemed to be water with some oily feel. There was no color, so I suspect the water had some fuel mixed in. Perhaps, at fill up, the tank had some fuel in left there. The low level is puzzling. The pipes were sealed very tight, but nothing is airtight, of course. It could be that during the years some water has evaporated. Who knows?
I have decided to fill up both tanks, just to see what comes to the surface? Once each tank was full, I could see just a little bit of oil on the top. I pushed in a rope all the way down and it was mainly wet with a tiny film of oil on it. The water looks very clean. I don't see any rust, crude, dirt, coming out, so far. I am not saying there isn't any on the bottom, but it looked clean enough.
Next step, I will add the rust remover you'd recommended and let it slush there for a while. Once I have the right place, I will pump out all the water and fill them up with fuel. The water looks clean enough to pump it out anywhere. I will just pump the top layer out with a shopvac.
Next, I will rig the tanks back to the manifold. I might even add another fuel pump with filters, so I can run through the fuel few times to clean it all up.
On and all, I feel pretty good about this result. I was expecting much worst.
I wonder, if the boat will be less tender, after I filled them up now completely?

 

[Juggerknot]

Great news!

 

[FF]

" The water looks clean enough to pump it out anywhere"

Great but in some places the sheen police may not like a tea spoon full of oil.

I would pump into the sink with oil absorbing pads in the self draining sink.

 

[LeoKa]

" The water looks clean enough to pump it out anywhere"
Great but in some places the sheen police may not like a tea spoon full of oil.
I would pump into the sink with oil absorbing pads in the self draining sink.

I was thinking about this myself. I have pads, so I will use those. Do you recommend several layers of pads, or just one and change frequently?

 

[LeoKa]

I use a product: Archoil AR5100. 1 oz/gallon. Dissolves only rust, leaves metal looking like it was sandblasted. Probably could be added to existing water before it's pumped out.

I tried to call the manufacturer, but I always get the answering machine.
I wanted to ask them about the dilution. The instruction says 1/15 ratio with water. If I need to clean two 400 gallon tanks with this stuff, it will be a lot of rust remover. Am I correct on this?

Also, it says that the water needs to be over 65F. Here in the PNW the water is much colder now. I could use some warm water from my sink, but I don't know, if that will be enough?

Lastly, this product is for submerging metals in it. It does not say anything about using it in tanks. Since, you have experience with this, have you use it for tanks before?

 

[LeoKa]

" The water looks clean enough to pump it out anywhere"
Great but in some places the sheen police may not like a tea spoon full of oil.
I would pump into the sink with oil absorbing pads in the self draining sink.

I did use the pads. All the water was filtered and pumped out. The oil/water mix at the bottom was interesting. First the water started to have white color. I suspect this came from the bubbles the impeller created, when the oil showed up. Later the water has changed to more creamy consistency. It looked literary like a thick milk. At the end, there was more oil, but still water present.

I wonder, what was the creamy flow? Whipped oil? Or, biological growth?

Regardless, I filled up both tanks with fresh fuel. 250/250 gallons. The tanks are sealed now and not connected to anything. My plan is to build a 3 stage filtering system and run the fuel through until I get clean fuel only. It will take a while and possibly many filter changes. It will be my fuel reserve. Once this keel fuel is clean, I will connect them to the fuel manifold and rig them, so they can be pumped to any of my side tanks, if needed.

 

[FF]

"I wonder, what was the creamy flow? Whipped oil?"

Probably , to avoid problems suck the oil thru the filter setup, instead of pushing.

That keeps the mixing of oil and water to a minimum, (Making mayonase)

This is less efficient than pumping so may require a better suction pump.

 

[mgardner]

I was following this all along and wondering what has happened with the tanks since?

 

[LeoKa]

I was following this all along and wondering what has happened with the tanks since?

The tanks are full with fuel and just there for ballast now. I will cleanup the fuel, when I can get to it. There are other more urgent projects now.
As I said earlier, I plan to reconnect these tanks with the others I have, plus build a type of separate filtering mechanism, which I will use to clean up this fresh fuel. I am sure the tanks have some water, bio, etc. left in there.
Time and money is limited, so this is a slow project.