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Since discovering our very dirty fuel filters, I have continued to explore the idea of having the tanks professionally cleaned. The day before yesterday, we visited our friends on s/v Feel the Magic to discuss our fuel situation as they had quite a bit of drama relating to dirty fuel last season. During our talk, Hank affirmed something that I was already aware of, that it is important to keep the fuel tanks full so as to minimize the condensation that can form in them. I mentioned that we had not yet topped up with fuel since Michael, Carl and Deb left on the 14th.

Yesterday, with our immediate chores in Long Bay having been completed, we decided to go around the western end of St. Thomas and head east to Magan’s Bay, a spot which we had yet to visit. As we got underway, we could feel that the wind was blowing a bit stronger than it had been the previous couple of days. That was not ideal for heading east but what can you do?

A passerby last evening.

While on route, before reaching the western end, I noted that the port fuel tank gauge had bottomed out, showing nothing. This gauge has not been functioning properly and in fact, only a couple of days earlier, I took a crack at troubleshooting it. I got so far as to determine, in my mind, that the issue is not being caused by a faulty connection between the top of the tank and the helm. That’s as far as I got though.

As we came close to rounding the corner to head east, we found ourselves in a washing machine of waves. That and over 20 knots of wind! We had been making our way between a number of small islands and rocks, and while we were not under sail, Rebecca and I made sure that the sheets and halyards were ready to go, just in case we experienced some unexpected drama.

I created a post on Facebook the other day posing the question “how much sea room do you require to feel comfortable when traversing a lee-shore coast line?” Personally, I like to have a fair amount, much more than I see many other ship Captains settling for. I always play the “what-if” game in my head, trying to have a solution prepared in case we experience some unforseen engine drama, a wind shift or a failed tack. Distance equals time in these situations.

Once we started heading east into the large swell, the wind was (of course) right on the nose and with both engines running at somewhat less than cruising revs, we were making about 5 knots comfortably (comfort is a relative term). At this point I considered transferring some fuel from the starboard to the port tank, just in case it really was as low as the broken gauge was showing. One Love is fitted with a fuel transfer pump with a control switch at the helm to address situations just like this. I decided to wait until we got to the calmer waters of Magen’s Bay to do so though, a spot which at that point in time, was about an hour away.

That’s pretty much precisely when the port engine died! Crap!

Assumed cause? Out of fuel.

With only one engine working, our speed and control in the wind and waves dropped considerably. This is precisely why I like to have sea room! I decided to do a 180 and run with the waves while sorting the situation out. Using the transfer pump that I mentioned, I moved some fuel from the starboard into the port tank and then while we were surfing down the waves, Rebecca got down into the port engine compartment to bleed out the air which was now likely in the fuel line. Good thing I showed her how to do that, isn’t it?

With fuel in and air out, we got the engine going again. Then, while the boat was still heading west, Rebecca took the helm while I got the jerry can of diesel that I keep up front and poured that into the tank as well.

Assuming that there would be no fuel at Magen’s Bay, and knowing that we now really needed to fill up, we changed plans and headed almost all the way back from where we had come from to Crown Bay to refuel.

With that fuel drama taking up our entire morning, we opted to pass on Magen’s Bay, choosing to save it for a time when the easterly winds are perhaps a bit less brisk. We opted instead to settle into nicely-protected Brewer’s Bay by the airport, another spot that we enjoy visiting. It may not have been exactly what we had wanted but it was still perfect to relax a bit, and complete the chores that we had lined up for ourselves.

Take home lesson: We need to get those fuel gauges working again!

Familiar sight at Brewer’s Bay.


  1. You might find the article “The Myth of Condensation in Fuel Tanks” by David Pascoe helpful – it is a bit old but I believe still very worthwhile.

  2. I’ve found that on my motoryacht when fueling that the total hours since the last fill up I can guess how much the tanks will hold within 5 gallons. The gauges work but aren’t accurate enough to use them on how much fuel is needed to top off the tanks. Northern Lights carries 304 gallons & I seldom let it get below half full. The best option is fuel flow meters to know exactly what you have left in the tanks, plus knowing the most economical cruise rpm, but it’s over 4 boat bucks for a boat with twin diesels more if you add one for the gen set, I’ld rather use that to buy more fuel. Take care

  3. interesting article on how water gets into fuel tanks. thank you for pointing to it. Regardless of whether or not air/water condensation leaves water deposits inside fuel tanks, the assertion that loose or leaky filler caps is a prime cause is pretty clear. In the tropics it is very common to find decks covered in dew in the morning. In my experience, flier caps are often very loose. Maybe they were never tightened properly, or maybe they vibrate loose. thanks again.

  4. It seems to me that you have become much much more comfortable with just going round to this bay or that, when the distances are greater than you would have done in ZTC without considerably more preparation.

    Do you find the massive 46ft Leopard to be much easier to use for getting about rather than the smaller but nippy 32ft?


    • Not particularly, although the ride in less than ideal conditions is certainly more pleasant. I seldom consider a trip from one bay on an island to another bay on the same piece of land to be a journey. Traveling from island to island is a different matter. This is what makes the VI such great cruising grounds as there are so many options in very close proximity to one another.

  5. Hey mike and Rebecca, we are just around the corner from you anchored across from Crowne Bay Marina. If you pass this while we are here, stop by… after we are headed to Caneel..

    Fred and Phyllis
    Lady J 111

  6. The funny thing about his myth busting is that he is dead wrong. I say this as a 30 years chemical engineer in the fuel business who also has more than 1000 internal fuel tank inspections under his belt. I’ve walked this ground.

    a. The code requires that before entering any large tank the rafters supporting the roof must be visually inspected. Under side rusting is very common and I have found fallen rafters in the sludge many times, rotted off by rust. In damp climates the underside of the roof is generally wet. Tanks always fail either on the floor or the roof.

    b. The water that drips into the fuel from the roof, how ever little, does not leave. Some goes to the bottom and the rest is emulsified. Both processes reduce the volatility of the water to where it does not re-evaporate. It’s like a one-way valve. Put another way, an oil tank is very different from an empty tank. Any logic pointing out that an empty tank does not fill with water is false analogy; it seems like common sense, but the comparison is fatally incomplete.

    c. You don’t need free water to get growth and corrosion. Just enough to cause the lightest haze, perhaps 50 ppm; only one teaspoon ounce in a 50 gallon tank. I have done lab testing on both corrosion and growth; free water is a very minor factor, it is the haze that gets you.

    d. You don’t need a full tank to prevent condensation, you need a vent filter ( Very effective. This one works (have tested it for 2 years) and you can make your own (I’ve done that too). Even better on e-10.

    e. Most water comes from leaking fillers. REALLY look at the o-ring and make certain rain does not get in.

    However, as much fuel as you are using, condensation seems unlikely; the process is too slow and mostly applies to stored boats. Most likely the fuel source or cap are to blame. But if it were me, I’d add a vent filter anyway. In lab and field testing, we demonstrated that a vent filter actually slowly dries the tank!

  7. This post demonstrates condensation and corrosion.

    I wonder what drives someone to “myth bust” without doing the testing?

  8. Oh well, we’ll keep and eye out for you along our respective journeys.

  9. “We need to get those fuel gauges working again.”

    Or equate your fuel use with engine time. *shrugs*

    • Sorry, but I disagree. Do you do that on your car? Are people still navigating solely by a DR?

      Just because that is possible to do something does not mean that it is the most practical way to do it.

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