In order for Sophie to cover the 2,900 miles from the Maldives to Egypt, we decided to augment our 250 gallons of on-board fuel capacity with additional fuel bags that we lashed to our deck. This blog post explains how we did it.

Many cruisers use 5 gallon plastic jerry cans arranged around their deck in order to add fuel capacity, but Jenna and I are not big fans of this approach. In order to avoid having to make stops in Aden, Djibouti, or Sudan for fuel, we figured we needed another 250 gallons of capacity on deck. That would mean 50 jerry cans, which would likely become a permanent installation on Sophie once we were done with the Red Sea! That was too much plastic for us. I also had multiple bad experiences refueling Sophie via jerry cans when we were in Indonesia, and I wanted no part of repeating that messy scenario again.

So instead we decided to try out a series of 52 gallon flexible fuel tanks that we would arrange on deck. They are manufactured by Nauta, and we purchased one from Defender.com in October and had some friends bring it with them to Thailand when they came out for a visit. These portable fuel tanks are made from neoprene and seemed sturdy enough for our passage, so we purchased four more from Fisheries Supply in Seattle when we went home for the Christmas holidays.

The bags come without any fittings, so we also ordered a 2 inch fill pipe (above) along with a 3/8 inch drain pipe for each bag. I called Nauta’s technical support, and they told me that for our scenario we did not have to vent the bags.

When we returned to the Thailand, my brother Rich was kind enough to attach the fittings to two of the bags that we were going to test on our Thailand-Maldives passage. This involved cutting circular holes in the neoprene, inserting the lipped nipple of the fitting through the hole, and then tightening down an attached gasket. There is a good YouTube video explaining how to do this, and I urge you to check it out before attempting your own installation.

To extend the fill pipe, we attached a 6 inch length of flexible hose with a PVC cap on the top. I purchased the PVC cap at a building supply warehouse in the US.

For the drain pipe, I used some spare half inch valves I had onboard Sophie. We attached these with a short length of 1/2 inch flexible hose and hose clamps.

In theory, we would be able to fill the bags through the fill pipe using a standard marina diesel pump and nozzle, and then while underway pump the fuel from the bag on deck into Sophie’s main fuel tanks.

In Thailand we filled 2 of the bags, and after Rich received a couple of diesel face splashes, we eventually got the hang of how to do so. We felt comfortable with only 45-48 gallons of diesel in each bag. We also had to really tighten the hose clamps and bag fitting gasket rings, but once we did so the bags didn’t leak. We tied the bags down to the deck with ropes tied to grommets on the bag corners. They remained remarkably stable while underway. We also had to train Hazel to NOT WALK ON THE BAGS as she went up to the trampolines for her gymnastics exercises.

We purchased a portable diesel fuel pump to move the fuel from the bags to Sophie’s main fuel tanks. This system worked surprisingly well.

For a fuel transfer while underway, we located the portable pump right next to the fill pipe for Sophie’s starboard diesel tank and then ran a short length of 1/2 half inch hose from the pump to Sophie. The fuel pump has a 12 volt motor and some power cables, and we attached these to a power source on Sophie’s starboard engine. Since Sophie has an internal fuel pump that transfers fuel from her starboard fuel tank to her port fuel tank, we only filled her starboard tank with fuel from the external fuel bags. This kept the system relatively simple and consistent.

We then snaked a 10 meter length of 1/2 inch hose from the portable fuel pump to the drain valve on the fuel bag we were going to use, attached the hose to the bag valve with hose clamp, opened the valve, and turned on the pump. Apologies for the dirty deck. That’s fish blood.

Quite frankly, we were shocked at how well it worked. For our test on the Maldives run, we ran a hose from a fuel bag on the port deck around the aft cockpit and to the portable pump by the starboard engine. We could see the fuel line fill in about 10 seconds, and it then took 10 minutes to transfer the 45 gallons from the bag into Sophie. We never spilled a drop.

The bag collapsed on itself as it drained, similar to how a camelback water container drains, and Rich aided the process by holding one end of the bag up to expedite fuel flow.

When we were done, we simply tied the fuel bag up in the air, let it dry out for a day, and then put it away. We only needed to use one fuel bag on the Thailand-Maldives passage, but the test was a complete and total success.

I am really glad we ran the test on the Maldives passage, because it gave us one less thing to worry about as we prepared for the run to the Red Sea. Two days before we left the Maldives, we arranged for a fuel barge to come alongside Sophie. We filled both internal tanks to the brim, along with 3 bags on the starboard side.

We also filled two bags on the port side. This gave us around 480 gallons of fuel for the passage. We located each bag over a bulkhead and secured them with ropes from each bag corner to cleats or hard points on deck. For two of these, I potentially had to run a rope from one bag under another bag and instead used a canvas strap to reduce potential friction.

I asked Lagoon if we had to worry about all of this weight on deck, since each bag weighed about 310 pounds. They said it was the equivalent of having 5 fat guys hanging out on a charter and shouldn’t pose a structural issue for Sophie. We never experienced any additional squeaking during the passage, although Jenna and I felt like the boat was heavy when we left Male.

The bags were stable on deck throughout the passage, including when we were surfing down 5 meter seas in 50 knot winds and when we were pounding into 2-3 meter seas while motoring. We transferred all of the fuel while underway without incident, including a couple of transfers in 25 knot winds. It is important to transfer all of the fuel in a bag in one process and to not leaves bags partially full. When we were done with a transfer, we simply left the bags tied in place on the deck and continued on our way.

Once we reached Port Ghalib, we cleaned up the bags, let them dry in the sun for a day, rolled them up, and put them away in a locker. I assume from now on we will always have at least one bag on deck every time we do an ocean crossing. And with the new portable fuel pump, I swear that I will NEVER SYPHON FUEL AGAIN!

Life keeps getting better, and this is one of the best systems we have ever put together on Sophie.