Cleaning the fuel tank of my Drammer 935 Classic yacht

Fuel problems are the number 1 cause of engine problems on yachts

BHPian Jeroen recently shared this with other enthusiasts.

PAN PAN; The aftermath!!

From my earlier post, it must be obvious that I had a very serious problem with the diesel fuel on Sirion. Even though I did manage to make it home, I did not feel confident taking Sirion back on the water again.

First, the tank needed to be cleaned. There are probably about 15-20 companies that provide a tank cleaning service. But probably less than a handful of them are reliable and have a good reputation. The main challenge is they are all booked up for weeks, sometimes months ahead. Fuel problems are the number 1 cause of engine problems on yachts!

Jip, the mechanic who helped me out in Rotterdam had provided a name for me. He knew the guy and when I checked out the company, it had excellent reviews. So I called him the next day. Mick, the owner, was pleasant and professional. Within an hour I received a quotation. I called him back immediately to discuss some of the details. Then my next question was, when can you come around? Mick replied, it will have to be in the next few days, or it will be several weeks later. I told him, next week is good, in fact next week is great. Let me know the date.

In the end, we agreed on Tuesday morning. He would send Matthijs for this job.

Next, I talked to our harbour master. We have a special mooring reserved for just these sorts of jobs. You are not allowed to do these jobs at your regular mooring. As you will see, this "calamity mooring" as we call it was perfect. Because Matthijs brought a lot of gear!!

I got up at 06.00 AM on Tuesday morning. At 07.00 I started up Sirion and moved her to this special mooring.

I had agreed with Mick I would open up the tank myself, to save time (and some money).

So I opened up the floorboards of Sirion

The inspection hole in the tank also allows for various bits to stick into the tank. Here you see the flange. On it are all the connections. Fuel suction, Fuel return, tank level indicator, and atmospheric vent.

At 08.00 Matthijs rocker up in his van. It was absolutely crammed with stuff. He has already downloaded some big portable tanks here.

Matthijs was a real gem. 6 months younger than me and like me a former Merchant Navy Engineer. And we had both worked for the shipping company NedLLoyd. So lots to talk about and stories to share!!

Eventually, we decided to get to work. First things first, pump out all the diesel.

Matthijs had put a tarpaulin on the ground to catch any spillage. On it, he put a variety of pumps, filters, drums, hoses, extension cords etc etc.

Matthijs handling the hose and pushing it in all corners of the tank to get as much diesel out as possible.

This is looking inside the tank, with almost all diesel pumped out. You can see a lot of debris and gunk on the tank. Matthijs and I discussed it at length. According to him, modern marine diesel is simply not very stable. As long as you use your boat regularly and replenish the tank regularly there are no problems. But if you leave the boat for months at a time, the diesel starts to deteriorate. Some of the additives start cluttering up and become what is known as a bio-grease. Next, there is also the dreaded diesel bacteria, regular debris, and of course water. Water ingress into your tank makes all of the above worse.

Notice that large ring at the bottom of the tank. That ring sits just underneath the opening of the tank. The bolts holding the flange in place thread into the ring, sealing the flange (with an O-ring underneath) to the tank. So it is effectively a retainer ring.

The tank was very dirty and Matthijs could not reach all the corners on the starboard side. So we decided to open up the floorboards on Starboard as well. We found a tiny inspection cover.

That tiny inspection cover was not large enough for cleaning, so I authorised Matthijs to make an additional proper cover. Outcomes the electrical saw!! I was a bit apprehensive, but Matthijs has installed hundreds of these and it showed!!

One rectangular hole cut. Plenty big to put all the hoses through.

Same sad story on the starboard side too!!

Next Matthuis used various tools to detach all the gunk and debris and hoover it up. When everything looks pretty clean, he then sprays down the inside of the tank with clean diesel oil.

Look at the result!! Squeeky clean!! Fantastic!!

Next, we had to put the flanges back on. When Matthijs retrieved that retainer ring inside the tank, a small part broke off. Right on top of one of the threaded holes. It looked as if somebody had already fixed this ring before.

We decided to position the ring underneath the tank opening and drill a couple of small holes. Next, we put two small bolts through with a nut and locking ring on the inside of the tank.

Then we drilled a new hole through the flange, through the tank into this retainer ring, and tapped thread.

See that narrow pipe on the left? That is the suction line of the diesel space heater. It has a very small diameter suction line. I took off the hose and blew through it to clear any debris.

With the tank all clean, and both inspection covers, old and new, ready to be fitted back it was time to pump the diesel back in. The diesel gets pushed through various filters so is absolutely clean when it goes back in.

The newly made cover on the starboard side was very easy to fit. The cover is just a large beautifully machined rectangular plate. It has an identical retainer plate and a gasket in between. Matthijs showed me how to install it. First, you put these two bolts in, they have white spacers. Which means they are longer than the other bolts. The two bolts in the two flanges are held together but there is sufficient room to get them into the hole. Next, you fit the other bolts (black spacers) and tighten them down evenly.

Once we had all the covers, pipes and hoses re-fitted I started Sirion's engine.

Matthijs and I debated whether we should bleed the fuel system first. But we were both confident that most likely the engine would self-prime. Just to be sure I put her on high idle and let her run for 15 minutes. No problem.

Also, the vacuum gauge on the Duplex filter showed very little vacuum and stayed well below the yellow arc.

I helped Matthijs load up. Matthijs also provided me with some special Diesel treatment fluid. I have some, but he preferred this stuff. So we added it in the tank prior to refilling it. I asked him to add extra as I was going to get bunkers right away.

At 13.45 PM I cast off and headed for the lock at Gorinchem to make my way to Werkendam. The same trip and the same bunker station you saw me visiting before. The weather was atrocious. I one point I had less than 400 meter visibility on the river.

But with every kilometre of motoring my confidence grew. I kept checking the vacuum gauge. Initially every 5 minutes. Especially once I had cleared the locks and went to full power I kept checking it. But even under full power for half an hour, the vacuum did not increase. All is good, Sirion is back!!!

Very happy and relieved!!

Tied up at the bunker station once again. I took on some 180 litres of diesel.

I am very happy with the result! It was not cheap, but it was necessary. Also, with these sorts of jobs it needs to be done properly. Or you are just wasting time and money. And worst of all, you are compromising your safety.

There is not that much you can do to prevent this. Other than keeping an eye on the vacuum gauge. With my new inspection hole, it becomes a little easier to have a peek inside the tank. Matthijs advised to clean the tank every 4-5 years. But again, it depends a lot on the usage of the boat as well. As I mentioned, the more you use the boat, the less likely it becomes a problem.

I will take that advice to heart!

Many thanks to Matthijs who did a stellar job!! And great to catch up with an old colleague.

Jeroen

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