Fuel Tank Replacement in Marmaris, Turkey

Photo: Tayana 37 fuel tank replacement. Credit: L. Borre.
We replaced Gyatso’s fuel tank in 2010.

Logbook Entry

Date: 2/15/10
Location: Marmaris, Turkey

Below deck, we replaced the 25-year old diesel fuel tank over the winter.  It was nice to return to the boat in Marmaris, Turkey and find that Demir Marine had done an outstanding job removing the old one and installing the new ones.  We weren’t having any trouble with the original, mild steel version except that it was showing signs of its age, especially where the boat builder had fiberglassed the tank to the hull.  We learned that this is the worst thing you can do to mild steel, which is otherwise a perfectly suitable material for the job, because it seals it off from the air.  In Gyatso’s case, the 90 gallon tank was literally rusting underneath and along these fiberglass seams, from the outside in.

Because the old tank was installed before the cabin was finished, there was no way to get it out in one piece. It had to be cut out in pieces.  This also meant that there was no way we could replace it with a single tank — it simply would not fit through the companionway into the cabin.  It was probably best that we were thousands of miles away when the old tank was removed.  It’s hard work and a messy job cutting into steel which happens to be located directly beneath our sleeping berth.  Demir Marine kindly emailed photos of the operation, which was as close as Lisa wanted to get to the project anyway.

The new arrangement is a two tank design in the same location as before, since moving the tank to a new location was not an option for us.  We went with two tanks so that they could fit in through the companionway opening, but this meant that we had to sacrifice about 10 gallons of the original 90 gallons of fuel capacity.

After much consideration about what material to use, all of which are readily available here in Turkey, we decided to use stainless steel even though John at Demir Marine explained that a replacement tank made of mild steel (a/k/a “black iron”) would be less expensive and perfectly suitable.  He said, “The one you have has lasted this long after all.”  We considered other options, too, but chose stainless steel in the end.

Until they cut into the old tank, we had no way of knowing what condition it was in.  We had to have the old tank cleaned not long after purchasing Gyatso in 2005 but have not had any problems with fuel since then.  Through the end of last season, we changed our primary Racor 5000 fuel filter every 100 hours out of practice, not necessity.  Occasionally, we would detect the smell of diesel fuel in the forward cabin after topping up the tank, but we think that this is related to the hoses or connections leading to the tank.  It turns out that the inside of the tank was still in good condition, and even John admitted, “You might have been able to get another 1-3 years out of the old tank — there’s really no way to know.”  

By the time we arrived in Turkey in February, the two new stainless steel tanks were fully installed and filled with new diesel fuel so that they could pressure test all of the fittings. Although it is always hard to know exactly when to finally “bite the bullet” and take on a project such as this, for us it was a matter of balancing out the anxiety about whether it would be reliable or not.  In keeping with the “if it ain’t broke, don’t fix it” motto we apply to some of our refit decisions, we could have continued to take our chances, but in the case of a fuel tank, we thought there were several downsides to delaying the project further.

First, if the tank did fail when there was fuel in it, we would have a real mess on our hands.  Second, the fuel would end-up in the bilge which could potentially result in discharging fuel into the marine environment.  As environmentalists, this is totally unacceptable to us.  Third, this sort of equipment failure could occur at the height of the cruising season when we least expect it or want to deal with it.  Fourth, it could also happen in a place where we have no control over what it might cost or the availability of qualified technicians.  And last but not least, it could leave us without an engine when we need it most, creating a safety concern.

Replacing the fuel tank has been on our list of refit projects since purchasing Gyatso in 2005.  We’re relieved that we didn’t have any mishaps and that we were able to “nurse it along” until we could take on the project.  It was a big investment for us, but the job was done for a fair price and exactly to our specifications — at least we no longer will be worried about whether we waited too long.

Here are some photos of the original tank while it was being removed by Demir Marine:

Photo: Tayana 37 fuel tank replacement. Credit: L. Borre.
The top of the old tank was rusting from the outside in, especially along the edges which had been fiberglassed to the hull.
Photo: Tayana 37 fuel tank replacement. Credit: Demir Marine.
A view inside the original diesel fuel tank after removing part of the top of the tank.
Photo: Tayana 37 fuel tank replacement. Credit: Demir Marine.
The inside of the tank was still in good shape, but there was no certainty about how much more time we would have before problems developed.