And no shade intended towards you Robert! Just another outcome. Cheers, b Sent from my iPhone > On May 24, 2026, at 19:24, Ben McCafferty <bmacpiper@me.com> wrote: > > Sooooo…. I have to provide the counterpoint here, and I apologize that it will be a long post. > > I have 37-202 “nessie”, now 16 years old. We have had her for eight years. Until last year, I also “never had a fuel problem”. In roughly 2022, we took a bad load of fuel on Lopez Island, and within less than an hour of runtime had a water in the fuel alarm. Over the rest of that summer, we pulled something like 3 gallons of water out of the two tanks, and there is no question where it came from. Approximately every one hour of runtime, we would drain a Racor filter full of brown murky water into a 5 gallon bucket that I ended up installing under the filter for the summer because we used it so often. Two of those times were in 7 foot seas on the way to Victoria, not fun. > > We also change filters regularly and have never even come close to having increased vacuum showing on the gauge for either filter. After the water incident, we continued to run biocide (not the brand that is recommended below, for what it’s worth), about once a year, and kept the tanks full when possible. We never again saw a single bit of water in a water separator filter, nor any alarms. To all outward appearances, everything was perfect. > > Last summer, we began to have a pinhole leak in both tanks. We made it through a long cruising season and in about November, the leaks suddenly became very bad, especially on the starboard side, which is the generator supply primarily. With > Four rotator cuff surgeries behind me, we had no choice but to hire one of two local respected companies to do the repair. I have been meaning to do a post about this with photos and will eventually get to it. > > But for now, I will let you know that we ended up cutting access ports into all five compartments of both tanks, 10 total, and we had corrosion through the entire length of the tanks. The tanks fall forward, so the worst corrosion was at the front, where water would sit for long periods of time.In case some are wondering, the last two tank compartments were accessed via the cabinet under the sink and its mate on the port side. In both cases, I used a router to create holes through the cabinet, and through the sole of the boat, with Nordic tugs’ input and permission, and the replacement carpentry work I did is pretty sweet. Added bonus is, I now have access to the entire diesel tank on both sides for the rest of the boat’s life. > > Complete aside, I also took the opportunity to add three access ports on the freshwater tank so that could be easily opened and cleaned, and the cost for adding those ports was almost nothing compared to the overall cost of the diesel repair. The diesel guys were very careful not to use any diesel tools in the freshwater tank like vacuums or anything like that and I bought brand new scrapers and had someone else do the interior cleaning. Definitely don’t want that flavor forever. The tank was in surprisingly good condition for its age, and we just did a scrape and a pressure wash and it was back in service right away. > > The fuel company said the diesel tanks were one of the worst cases of corrosion they have ever seen. As a reminder, we never once saw water in our separators other than the bad load of fuel. I can’t say for sure, but my suspicion is that the bad fuel also introduced lots of microbes, which eventually corroded both tanks, despite regular, but not religious, use of biocide. You can imagine that I am now going to be religious about this. Fuel company recommended minimum once a year, ideally twice a year, and only recommended a single product: Biobor JF. Also to keep the tanks as full as possible to minimize condensation. > > The fuel company was able to do two coats of epoxy and the leaks are fixed. They warrant their work for five years and I doubt we will see the problem again. They were quite thorough. > > When the tanks were completely open, one thing I saw/noted is that the fuel pick up on either side, and the crossover connections, both leave some space between them and the bottom of the tank (they pickup out the side, it out the bottom). I have no doubt that water can sit there for a long time and cause corrosion if no biocide is used. The fuel polishing system you propose will not take care of this problem, because there is no way to draw all the water out of the tank if you have any. The only thing that will help is to regularly empty the tanks of everything, which is pretty easy to do if you install an access on the forward compartment of each tank and at the end of the cruising season, leave the tanks relatively empty, and you could have someone pump the tanks for you and polish the fuel before putting the diesel back in. Your call on whether this is worth it or not, but I would say it depends on what you find when you had an access panel. > > I will leave it to your imagination on what such a repair costs… let’s just say it is quite a bit more than a couple of boat dollars. > > As you may or may not have seen on previous forum threads, both the main and the genset return far more diesel to the tanks than they burn, so in a sense, the system is self polishing as it is. > > In my experience, the one good reason to install a fuel transfer pump between the two tanks on your crossover, where you could also add an additional Racor filter if you really felt the need, is so you can move diesel from one tank to the other on demand. We did have a situation once where we had about 40 or 50 gallons left in the starboard tank, wind was on our port side, and the boat was laden on starboard, and we ran out of fuel with 50 gallons or whatever in the tank. We were able to use the thrusters to spin the boat around and move a bunch of our crap to the port side and got restarted and limped into a fuel station. Fortunately it was in the right direction! > > I’m sorry this is a very long post, but it is yet another story on our Nordic tug that seems to have been experience hard won through some bad fortune and a lot of dollars. We seem to have quite a few few of those on here! > > So, the bottom line— > If I had three takeaways, they would be: use biocide like your life depends on it because it does, consider a transfer pump to move diesel back-and-forth, and add access ports to the front compartments of both tanks. You will not usually know about fuel problems lurking in your tanks until you are in the roughest of conditions, when suddenly all the water and muck get stirred up and find their way to your filters and shut down your Main in the worst conditions possible. One other tip, if the tanks are not full, you can remove the fuel sender unit at the very top of either tank and use a waterproof borescope to look down inside without adding an access panel. It’s a little crude, but definitely a workable start. (One might have such a borescope if one had blown up an engine and needed to look at an exhaust valve through a fuel injector hole, say… but a couple hundred bucks on Amazon if not) > > As always, your mileage may vary, this is one experience and is probably worth what it has cost you to read it. Not sure if photos will come through on email, but I will attach a couple of the interior of the tanks when they were first opened. The big blobs are living colonies, everything else is dead and decaying and acidic, working on making holes in the aluminum. > > Happy cruising and talk to you later, > Ben > 37-202 nessie > > Port > <IMG_1497.jpeg> > > Starboard > <IMG_1500.jpeg> > > Sent from my iPhone > >>> On May 24, 2026, at 18:45, mmcb396317 via Sentoa <sentoa@lists.sentoa.org> wrote: >>> >>  >> Hi Robert >> My tug, Kismet 2006 37-158, sits in the water at my dock unused from early October to end of April every year for the past 12years . >> Aside from leaving the tanks relatively full in October, I have never had a fuel problem. I change the fuel filters in early May every year. I don't think you have to worry about fuel polishing which can be an expensive proposition. >> Best regards >> Mike McBryde Kismet 37-158. >> >> >> >> Sent from my Galaxy >> >> >> -------- Original message -------- >> From: Robert Leviton via Sentoa <sentoa@lists.sentoa.org> >> Date: 2026-05-24 9:30 a.m. (GMT-08:00) >> To: Sentoa List Serve <sentoa@lists.sentoa.org> >> Cc: Robert Leviton <Robert@RobertLeviton.com> >> Subject: [Sentoa] Any suggestions for Fuel Polishing >> >> After a transmission snafu last boating season, my NT 42-047 (now named Tiramisu) was on the hard for some time. >> Readying for this season, thought it best to consider fuel polishing systems for the stored 400+ gallons of fuel . >> >> Has anyone added a fuel polishing system to their NT? >> Are there DYI models recommended or commercial items withing a reasonable cost range? >> Design elements, set up options, and other recommendations would be greatly appreciated. >> >> Thank You >> Robert >> >> Robert Leviton, MD, MPH >> Tiramisu 42-047 >> Mobile | +1.914.715.8102 >> Fax | +1.914.381.6819 >> Email | Robert@RobertLeviton.com<mailto:Robert@RobertLeviton.com> >> >> _______________________________________________ >> Sentoa mailing list -- sentoa@lists.sentoa.org >> To unsubscribe send an email to sentoa-leave@lists.sentoa.org