Designed for efficiency – it’s a hull of a challenge
As a passenger, you'll never see one of Honfleur's most complex and impressive features, but you'll certainly feel its benefit. Your car's body has been designed to slip through the air as cleanly as possible to maximise its fuel efficiency, and the hull of a ship is designed to do the same: just think hydrodynamics instead of aerodynamics.
But that seemingly simple shape has to do a lot more than just be slippery. It has to be safe, of course. It has to hold the vast engines, gearboxes and tanks which the ship needs to sail, and the parking lanes for the cars and trucks it must carry. The shape of the hull has a huge impact on a ship's manoeuvrability in port and its stability at sea, and a good design reduces the vibration you can sometimes feel from the propellor. So that shape lurking beneath the water not only makes your crossing cleaner and faster, but more comfortable too.
Unsurprisingly, creating a 'hullform' that can do all of this takes just as much talent and technology as designing a new car. Heike Billerbeck is the Head of Ship Theory and Hydrodynamics at FSG, the shipyard where Honfleur is being built. Heike and her team, including propellor specialist Thomas Stoye, spent around three months creating a digital model of the hull, and testing it using computational fluid dynamic software.
They can visualize the size and angle of the bow wave and wake the ship will create: smaller waves mean less wasted energy. They can create animations of how Honfleur will perform in heavy seas. And they can calculate exactly how much power Honfleur will need to sail at a given speed, ensuring she hits the demanding efficiency targets set by Brittany Ferries.
"Technology has transformed the way we design hulls," says Heike. "Over the last 20 to 30 years we've reduced resistance by between a third and a half."
"And the technology is improving all the time," adds Thomas. "Ten years ago our simulations might have taken a month to compute. Now we can get the results back overnight."
But despite the accuracy of their virtual tools, every hull design at FSG is still subjected to a traditional tank test, in which a nine metre long wooden model of the hull, complete with propellor, has its resistance measured as it 'sails' down a 300-metre pool in Hamburg.
The results prove that it's not enough just to have the software: you also have to know how to use it. "I'm pleased to say we've never been beaten in a tank test," says Heike. "And the results are never a surprise. We set tight targets, and we hit them."
So will passengers be able to feel the difference her hull makes when they sail on Honfleur? "Definitely," says Heike. "Of course, being gas-powered, she will be more refined anyway. But we have added a radical new propellor design which is almost silent."
"And the great thing about Brittany Ferries is that they know exactly what they want. They know the routes that Honfleur will be sailing, and even the times and speeds, so we've been able to optimise her hull design to match. We've taken into account her passage down the long, shallow Ouistreham channel, for example. This really is a bespoke ship, and she'll be more efficient and more comfortable as a result."