Learning all about Tulum’s Tanks…The Hard Way. Wanna talk Sailboat Fuel Tanks....read on

When you buy a boat…you really don’t have many ways to learn about the state of a boat’s tanks except by surveyor observation, questions answered by the boat’s owner and any knowledge that the brokers might have and disclose.  No one clued us in that we might have a very large fuel tank with large holes in it on the boat we were about to buy….but it is buyer beware, isn’t it!  While prepping for Baja Ha-Ha 2019, we discovered one of our fuel tanks had a small leak but didn’t have an immediate need to get that tank removed and fixed….our engine repairs took precedence during the last six months.  So leaving San Diego in November of 2019, we rolled out with just two of our three fuel tanks full of diesel and didn’t look back.  Fast forwarding by 8 months, we’ve never gotten ourselves in a situation where that 3rd fuel tank would have made a critical difference, but COVID has changed our perspective about preparedness and cruising off the grid.  Knowing that we want to be off the grid for weeks at a time and preparing our family to spend months in the Bay of LA area of the Sea of Cortez; I wanted the ability to go for long lengths of time without refueling…so that 3rd fuel tank suddenly took on more importance.  While getting engine work done in Puerto Escondido, we stumbled on a qualified mechanic who also worked closely with a team of welders in his hometown…about 70 miles away.  He did a quick initial inspection on the 3rd fuel tank and was quickly able to tell us (in translated Spanish) that he could get the tank out and have it fixed…and that both of our water tanks and the 3rd fuel tank were actually INSIDE another tank.  Huh?  Yup…all three of our tanks are really inside a much larger older tank…probably a large original water tank.  What I think is that the older water tank was cut open when the previous owner (who circumnavigated Tulum) wanted more fuel capacity and didn’t need a super large water tank because he added a water maker to the boat.  So, after careful consideration and discussion of our future cruising plans, we decided that finding this mechanical and welding capability in this place at this time was fortuitous…and decided to have the work done.  The work would include taking out the water tanks and old fuel tank, getting the tank repaired and then put back in.  Easy…right?

First, the original tank that was cut open has the arrow pointing at it. Then tanks # 1 & 2 are our water tank and # 3 was our old existing fuel tank.

Our crack mechanic and his helper arrived on the appointed morning and in short order (with my help) had our water tanks out and had moved on to getting the fuel tank out.

Both of our water tanks sitting in our salon (living room).
Fuel Tank in the process of getting pulled out of it’s space and ready for removal.
Prepping the tank to come out through the main hatch.

This was easier said than done…but eventually the fuel tank came out and was quickly prepped to be taken out of the boat…through our main entry hatchway.  Unknown to us, the tank was black iron and weighed much more than our water tanks (aluminum).  Onto the boat to help comes the relief team, made up of two more guys…one of them in a full wet suit as he had been out doing a bottom cleaning.  The tank did come through the main hatch with some minor cosmetic damage and was spirited into the hull cleaning panga for transport. While it was there, I was able to get in and take a close look at the holes in the tank.

Holes in our fuel tank, on a corner seam.

The holes in the tank were fairly large and they were in the underside seams and corner of the tank, which was already a loud and clear warning that the tank was likely not a good candidate for a strong welding repair job.  The tank was also confirmed to be black iron.  The next day, we were told that the tank could be repaired, but since it was black iron and already damaged…we opted to have a new aluminum fuel tank made.

This decision made, we were now told the new tank would be ready in 5 days, but the guys said in reality we should give the welders 10 total days to make the tank.  So, with our water tanks reinstalled, we took off for two weeks of cruising the islands and getting off the grid, eager to get our new tank when we returned to Puerto Escondido.

Tulum’s New Fuel Tank (3 weeks later)

After two weeks of cruising, we returned to Puerto Escondido expecting to get our new tank and get back out of the marina in a week or less.  Umm, we should have factored in a few more days…cause we sat at the dock (paying slip fees) for five more days while we waited for the tank to finally get finished.  When it was finished, the work was very well done and seemed to be solid welds and we HAD A NEW TANK.

On our boat, we don’t have a lot of new and unbroken stuff, so a new tank is a big deal for us.

Since the tank was delivered in mid-afternoon, I had no expectations that it would go in the same day, but Lauro and his assistant started right up; with me and Michelle fully assisting them to get the new tank into the boat via our narrow main hatch.  But the tank was aluminum and lightweight so we easily managed to get it into the boat.  Working together, we quickly had the empty water tanks back out of the boat and sitting in the salon.

New fuel tank in.

Next the new fuel tank went back into the boat perfectly (with some work) and we put the water tanks back into the boat.  In three hours and some sweaty hard work, Tulum had a new fuel tank and her water tanks back in.

Water and Fuel tanks back in, final touches and clean-up begins.


The next day, I added my first 40 gallons to the tank and carefully watched my bilge for signs of diesel leakage, but haven’t found any yet.  I also took paid the bill for the tank and labor- it was exactly as quoted with no extra fees thrown in.

Gotta stop and comment specifically– in the US the work probably would have taken several days with a myriad of consultations and extra helpers on each end of getting the tank out and put back in.  Specifically, there may have been travel charges to evaluate the tank removal, tank disposal charges for the old tank, hazmat charges because the old tank had some diesel in it, movement charges to get the new tank to the boat and taxes on top of that.  And…in the US they may have demanded that we move the boat to a boatyard to do the work on top of all the other costs I mentioned above.  In Puerto Escondido…the company rolled all these charges into one bill that said: new tank and labor charges; and the bill was nearly exactly as quoted.

The work described in this blog post was done in Puerto Escondido, BCS Mexico by a skilled mechanic named Lauro, his assistant and me.  Lauro works for Cristiani and Company at Marina Puerto Escondido and they provide a myriad of boat services, including mechanical work, hull cleaning and painting.

For dummies like me…just the thought of getting a tank taken out of my boat and repaired or replaced used to send shivers up my spine as I broke out in a nervous sweat thinking of the cost and complexity of the task.  But in the end getting the tank out didn’t take that long and getting the new tank custom made and put back into the boat wasn’t nearly as costly or labor intensive as I had always imagined.  And that my friends…IS THE PURPOSE OF THIS WEBSITE.  Stuff on a boat just isn’t as fearsome as most think….do it yourself or assist whoever does do it, so you can learn for yourself next time.  So as you read this…if I can do it…you can do it.

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4 Responses

    1. We’re all doing great. Docked in San Carlos as planned so we have AC. Still hot inside in the middle of the day but at least we can sleep now. Going to have a whole boat shade made up next week which should make a massive difference. 99 today and very humid!

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