Monday, April 15, 2013

The end of a two-year project

Two batteries still have to go back in.

This morning we reached the end of a two-year long project.  It started in June of 2011 with the removal of the fuel daytank.  Back then, you might have thought that the tank was the project - but it was only the first phase of the larger project...

Repairing the Leaking Port Fuel Tank

Because it had a slow leak, we have never used the port fuel tank.  Eolian has two fuel tanks, each 150 gallons, so this was not a hardship.

Nevertheless, in the fullness of time, all problems must be addressed.  Including this one.  One of the advantages of being moored in an area with a long maritime tradition is that there are a whole host of marine services available - services which would not be available elsewhere.  One such service is the repair of fuel tanks provided by Felix Marine.

The difficulty with tankage on boats is that the tanks are physically large, and are by necessity located as low in the boat as possible (to keep a low center of gravity).  This means that the tanks are frequently the first thing to go into the hull during boat manufacture, and the rest of the boat is then literally built around them.  Doing any kind of work on the tanks therefore is difficult.  In the worst case scenario, the entire interior of the boat must be deconstructed if the tanks are to be replaced - expensive and, well, destructive.

Daytank removal: First cut

Which takes us to the removal of the daytank.  With the daytank out of the way, access to the port fuel tank was possible, kind of.

The Felix Marine professionals carefully cut three holes in the structural bulkhead which concealed the tank.  Then they cut holes in the tank proper.  Following a thorough steam-cleaning of the tank interior (imagine the environmental gear that had to be set up out on the dock for that!), an epoxy mix was applied to the tank interior, and cover plates were installed.  Finally, I repainted the area and installed the access plates and door you see in the picture above.



So why was the tank leaking, you might ask?

The usual case is that the fuel pickup tube does not go to the bottom of the tank.; eventually, condensation produces a layer of water in the bottom.  A microbial culture gets started in this water, eating diesel for a living, and makes the water acid...  acid which then pits the tank bottom.

But not in Eolian's case.  Eolian's tanks have the fuel pickup going to the absolute lowest point in the tank.  Water buildup is simply not possible - any condensation will immediately be picked up and trapped in our big Racor filters - an arrangement I think is superior.

So what was the problem?

Amazingly, after the tank had been cleaned, I found a lead fishing sinker (with a few feet of line still attached!) wedged into the very bottom angle of the tank.  How or why it got there, I have no idea (your speculations are welcome!).

Lead and aluminum (our tanks are aluminum) are quite far apart on the electronegativity scale.  Thus it is entirely likely that the aluminum tank gave up protons to protect the lead from corroding, creating a pit under the sinker where the metal simply dissolved.

In any case, the epoxy applied by Felix has solved the problem.  The tank doesn't leak, and so now Eolian can carry 300 gallons of fuel (presuming the bank will loan me enough money to buy it)!



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5 comments:

middlebaysailing said...

Bob,

How do you manage your fuel storage? Do you keep tanks full? Use the diesel for heating too? How much fuel do you use for propulsion? For how long do you keep fuel, and how often do you have to treat it with biocide?

Seems like a management puzzle to me. . .

Rick

Robert Salnick said...

Hi Rick -

In general, I can *afford* to keep them full - 300 gallons of diesel would run me roughly $1500 at the dock. So, no, they are not full.

Yes, we use diesel for heating, but only as a supliment when the temp drops below 40. Above that (the huge majority of the winter here in Seattle), the heat pump takes care of things.

For propulsion? I don't know. Not very much - less than 100 gallons a season.

And yes, I use Biobor JF in my fuel.

But all the past experience is onloy a guide. Now I have *two* tanks to manage...

bob

Drew Frye said...

Very nice.

Though nearly everyone has a "PO" story to tell, yours tops mine, unless we talk about the electrical system on my prior boat....

stevek said...

We also had felix 'do' our fuel tanks, two 35 year old steel tanks, 150 g each, in a fiberglass cruiser. Not an inexpensive undertaking, but in our instance the best solution to a leaky tank. I think it was felix who suggested that biobor was part of the problem as it helped in the creation of an acidic sludge. I am pretty sure they recommended we switch to a product called StarTron. Anyway, it is a relief to have trusted tanks.

Robert Salnick said...

Hi Steve -

Thanks for the info. Drew (above) is doing a corrosion study right now...

bob

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