The Fuel System

Jun 27th, 2021 James The Build

Boats have a number of critical systems, whether electrical, navigational, or water and sanitation. But when the wind isn’t blowing, or you need to maneuver in tight spaces, the engine system is the one you care about most. And, in turn, an engine is nothing without the fuel system!

First some orientation:

In the photo above we’re looking backwards (from where the master cabin will be) past the mast step. The top of the metal frame is the floor level for the port-side galley (on the right) and the slighly higher dining area and navigation on the left.

Under that floor is some crawl space (and maybe room for some wine!), and then below that, there are six large tanks arranged in three pairs.

The middle pair of white tanks are for water (the topic of a future post!), and the starboard tank furthest back is for ‘blackwater’ - that is, sewage. The other three are fuel.

The front two tanks that you can see are the standard fuel installations, going deep into the hull. Here’s a close-up of the top of the starboard tank:

Each of these contains 350 litres (or liters if you prefer) of diesel. And there are lots of pipes going in and out… one to fill it, one to provide a vapor release when filling, one to extract fuel to take to the engine, and one to return any unused fuel from it. The electric probe is the fuel gauge.

The remaining pipes allow the pump (at the top of the photo) to transfer the fuel between the other tanks so we can keep the boat balanced regardless of which supply the engine has been using.

Inside the tank, the pipes drop to the bottom of the hull, even for those that fill it. This reduces aeration of the fuel: if the fuel drops like a fountain into the tank, the air entrained in the fuel causes the engine to run poorly.

You’ll also see that the tank features several large aluminium plates mounted vertically. These act as baffles, and as Scout rides the waves, stop the fuel sloshing about. This would again introduce air to the fuel mix and also cause the boat to be less stable.

In this view, we are in the engine chamber looking forward:

The blue tank on the right is the blackwater sewage, and on the left, you can see the extra third fuel tank we’ve had installed under the galley. This is another 285 litres, bringing us up to almost a thousand litres (260 gallons) when fully topped up.

For marine diesel, that’s a $1,000 fill-up! But other Exploration 45 owners we know are getting an average 5 knots on about 2 litres an hour. So in theory, full tanks would allow us motor solidly for three weeks and travel 2,500 nautical miles (such as across the Atlantic) under power - if for some mysterious reason there was no wind! In reality we might be able to go as much as a year without filling up, and choose where in the world to do so.

Moving further back, the fuel line goes through an Algae-X conditioner that helps pull out any ferrous material from the fuel.

(Far more terrifying in this photo is the sheer number of other cables that have already been installed around the engine. We think that is the start of the electrical system - of which more in a future post too!)

Just before the fuel reaches the engine (which has not been installed yet), it passes through these water separator filters. In these, a centrifuge spins off the large solids and water droplets which fall to the bottom of the collection bowl, and contaminants of even a few microns are filtered out.

Yep, lots of gadgets and things to get used to! Honestly the hardest part at the moment is trying to figure out how everything fits together with only a few photos for reference. But every batch of new photos is a reminder there are still lots of things about Scout to wrap our heads around.

If all of this leaves you still a little confused about how it all fits together, this video from the owners of Snow Gum (a similar configuration) gives a good idea of what is going on under the saloon:

Stay tuned for more posts soon! We hope to do runthroughs of some of the other systems as soon as more news from the yard emerges!

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