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  • Writer's pictureSailing The Dream

2019 Fuel, engine hours & nautical miles summary

One year later the fuel consumption is still a taboo subject, no one really wants to discuss it.

Seems like admitting how much motoring one does is a reason of shame and embarrassment, but our goal for this discussion is not to brag of "how good" sailors we are because we don’t motor, etc our goal is to understand engine efficiency and tuning, optimal RPM usage, related costs with fuel purchase and the inevitable engine servicing.

In our opinion, there’s no shame in the number of engine hours and purchased litres of fuel. Let’s be real about it, the engine is there to be used and needs to be used to be kept in good shape.

There are plenty of good reasons to fire up the engine and motor, from bad weather to emergencies or to the simple fact that we are not in the mood for sailing and in a rush to get somewhere, etc.

If we were to be purists about this sailing business, we should simply remove the engine from the yacht. It would save us a lot of money on servicing, spare parts and provide us with a lot more storage capacity.

Having said all the above, we still try and sail as much as possible. Although sometimes we just want to motor and there’s nothing wrong with it!

Because we don’t track the miles done under engine and the miles motor-sailing, neither account for all the times we need to start the engine to drop/lift anchor, etc our study will never be 100% accurate, but we think it still is a good exercise. When analysed in conjunction with the logbook transcriptions, where some of that information is expressed in more detail, it is possible to get a good idea of how much we motor and the reasons why.

To try and keep the data consistent, we track all the purchased fuel for a year run, including the full top-up of the tanks at the end of the year.

The fuel in the emergency jerrycans (100 litres) is only counted when moved into the tanks, the same applies to the fuel kept on the newly installed tank (140 litres), which we now call tank 3 and that is isolated from the yachts original fuel system.

Basically, we start each year at full capacity (2x250 litres in the yacht original diesel tanks) and account for each litre added in these tanks until the end of the year when we do a final top-up.

Recap of the first two seasons aboard The Dream for analysis context:

  • The 2017 season was the Shakedown Season. We travelled 2424 nautical miles, mostly in the North Atlantic ranging from Portugal (Lisbon) to Gibraltar, the Morocco Atlantic coast and the Madeira Archipelago. Purchased 1132.5 litres of diesel and ran the engine for 202.5 hours.

  • The 2018 season was the season we entered the West Mediterranean Sea. We sailed from Portugal (Cascais) to the Balearic Islands, Sardinia, Corsica and sailed almost to all the Italian islands from Elba to Sicily from where we crossed to Tunisia. This totalled 2406 nautical miles, 298.2 engine hours and 1253 litres of diesel purchased.

During the 2019 season, we sailed in the Ionian and the Adriatic Seas, exploring the great sailing grounds of Greece and Croatia but also discovering the amazing coastline of Albania and Montenegro.

The first half of the season was marked by unpredicted weather and by self-imposed schedules (we had to get Trieste, Italy to pick up our new solar panels), both situations contributed to an increased usage of the engine.

While during the second half of the season we took advantage of the near windless days we experienced in between storms in the north Adriatic to further improve our light wind sailing skills.

This allowed us to truly enjoy sailing in the Croatian Islands and reduce the usage of the engine. Many times we were the only ones with sails out tacking and jibing our way, taking quite a few hours to change anchorages even when we could have just motored for one hour to get there.

We also visited a much higher number of anchorages than in the previous year and managed to stay out of marinas from the end of March until the first week of October (when we had guests visiting us).

The last passage of the season also brought us a huge surprise, that ended up costing us many engine hours between testing the alternator and keeping up a SOG (speed over ground) of 6 knots to avoid being caught in stronger winds.

So at the end of the season, we accounted for 3046 nautical miles, nearly 448 engine hours and 1345.5 litres of Diesel purchased.

2019 Fuel, engine & nautical miles summary

At first, glance, when comparing the three years, it looks like the engine hours have been increasing quite a bit but the distance covered didn’t increased at a similar pace. When looking at the number of purchased litres of diesel the increase wasn’t as steep as the engines hours also.

An interesting situation that we can attribute to a few different reasons:

  1. during the seasons of 2017 and 2018, we ran the engine always at 1800 RPMs while during the season of 2019 we kept it mostly at 1600 RPMs. During this season we came to the conclusion that the amount of fuel used while motoring at 1800 RPMs didn’t really justify the speed gains (around 6 knots without tidal influence) when comparing to the fuel consumption of motoring at 1600 RPMs (around 5.6 knots without tidal influence);

  2. this season we did a lot of motor-sailing due to weather conditions, schedules. We tried to sail as much as possible but there were many occasions we had the need to "boost" our speed by using our engine to keep speeds of around 6 knots;

  3. the increased number of visited anchorages also meant running the windlass more often (to run the windlass the engine needs to be used), this added with the many times we had to relocate within the anchorage due to weather conditions, neighbouring boats anchoring too close and poor holding;

During the season we ran a couple of tests to double-check the fuel consumption and the numbers seem to be well within the expected range for our engine, hence the analysis above.

The reality is that the further East we have sailed in the Mediterranean Sea and the further North (Adriatic Sea) the more challenging the winds have been.

The big mountain chains that define the landscape of Mainland Greece and the East Adriatic and all the islands on these sailing grounds create lots of areas with Katabatibc winds and big wind shadow zones, giving reason to the most common comment regarding sailing in the Med “there’s either too much wind or not enough wind” and the acronym MED motor every day.

We think that although it can be challenging at times it is not impossible to sail more, we just need to avoid schedules and make the effort. Hopefully, the 2020 season will be more sailing and less motoring.



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