With the initial design phase completed, we gain more and more understanding of how big the gains are that we are able to make with the LM65h. Do you remember how, in earlier posts, we concluded that many motor yachts are theoretically able to cross an ocean, but that they lack the efficiency, the comfort, and the simplicity to make such a journey a de facto reality? Well, stating that is one thing, but how does our new approach to passagemaking pay out? Does an “outside-in” approach to motor yacht design bring the efficiency that we were looking for? And how does it compare to other, existing designs? The results are in. The outcome is flabbergasting. Let’s dive in deeper.
As most motor yacht designs do not invite their owners to cross oceans, we wanted the LM65h to be different. We wanted the ship to be simple (so it could be a trustworthy companion on those long voyages), comfortable (so the experience of crossing an ocean would be delightful), and efficient (in other words: affordable).
The basic flaw, that we found in most motor yachts, is that they are designed “inside-out”. The focus is on creating as much interior space as possible, given a certain length. This leads to bulky, wide, heavy, complex boats, that bob over waves rather than cut through them. Full-bodied boats with bad underwater ship design characteristics. Bad for comfort and bad for efficiency.
At Liquid Management Yachts, we focussed on the aforementioned “outside-in” approach. We didn’t want to design a boat that’s great for in-harbor living. No, we wanted a boat that is great for sailing over long stretches of water. We found inspiration in sailboat design. Sailboats have a very energy-scarce propulsion system (wind & sails) and need to be efficient. While they search for wind, they encounter waves, so the sailboat design has to effectively deal with those as well.
Back on topic? Here we go: let’s find out if our new design paradigm pays off. Is the Hammerhead efficient? And how does it compare to an equally long “traditional” motor yacht, that is based on interior maximization.
Here is the conclusion: the Liquid Management Yacht design is very efficient. See the graph underneath:
At her fast cruising speed of 10 knots, depending on load, she uses 80 to 90 horsepower. At lower, energy-saving speeds like 9 or even 8 knots, only 55 to 40 horsepower is needed.
Comparison to an existing design
The Nordhavn 68 is slightly longer than the LM65h. Its length over water is slightly shorter though. Yeah, sure it is a ship that is incomparable to the Liquid Management Yacht in many respects, like that it is wider and higher and offers an extra room, and costs more than twice as much, but that is not the point here.
What the point is? That the Nordhavn 68 is a perfect example of a ship designed conform the traditional “inside-out” design. And that’s what we want to compare here: the efficiency of our “outside-in” LM65h vs. the traditional “inside-out” Nordhavn. Because that’s the paradigm we choose and that’s the paradigm that needs testing.
A Nordhavn 68 displaces 93 (metric) tonnes. That’s about thrice as much as the LM65h. At our preferred cruising speed of 10 knots, we need the engine to produce 80 to 90 horsepower. That kind of power asks for a 17 to 18 liter hourly fuel-burn. Based on the weight of the Nordhavn 68, given an equally efficient underwater-ship design, the more traditional design is expected to need 270-ish horsepower and burn 55 liters per hour.
As an owner of a Nordhavn 68 (the latest model) informed us, his boat actually uses a lot more. It needs 400 horsepower and burns over 80 liters per hour at a 10 knot cruising speed. Now, hold your breath, as we compare these outcomes to the LM65h in the conclusions underneath …
Our “outside-in” approach to motor yacht design results – with the generator producing 24 kWh for daily electrical consumption – in an ocean-crossing ship that consumes one liter per kilometer at a speed (metric this time) of 18,5 km/h. Metrically speaking, the LM65h runs 1:1.
With some power generation on (the Nordhavn will need much more electricity than Hammerhead), the “inside-out” approach to motor yacht design results in a diesel consumption of about 5 liters per kilometer. The Nordhavn 68, at 10 knots, runs 5:1. Five liters of diesel are needed to sail one kilometer. One liter brings you only 200 meters further.
The “outside-in” paradigm to motor yacht design, that we developed at Liquid Management Yachts, results in a 80% lower fuel-burn. The LM65h is 5 times or 500% more efficient than a traditional design! (Mike-drop)
Nordhavn 68: roomy yet inefficient: