Hanse’s E-Motion Electric Rudder Drive

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           Hanse’s E-motion electric rudder drive represents a true breakthrough in auxiliary propulsion for saiboats   

           Hanse’s E-motion electric rudder drive represents a true breakthrough in auxiliary propulsion for saiboats   

When news that Hanse Yachts had launched a new form of electric-powered yacht first broke in the winter of 2016, it was widely reported. After all, Hanse is one of the world’s biggest builders of sailing boats, so this had the feeling of a breakthrough to it.

After nearly a year, though, just a handful of the “E-Motion” rudder-drive-equipped Hanse 315s have been sold, and by its own admission, Hanse is disappointed. “The problem is that people are still quite skeptical about electric propulsion on water, and we are perhaps a bit ahead of time with this,” says Hanse’s Florian Nierich.

It’s not a problem with the boat itself: the 315 is a feisty little sailer that has already sold 140 units, including more than 15 in North America. The issue is price, a basic diesel-equipped 315 costs $120,300. Stick an electric motor on, along with the necessary lithium-ion batteries, chargers, controllers and more, and you add $13,270. If you want a kind of “turbo-charged” system with more batteries and a charger that will allow you to top off in as little as three hours, that will set you back $26,554.

“The boat is way too cheap for the electric motor,” admits Nierich, “If a customer had the extra money, they’d buy the Hanse 388 instead.”

Which is not to say that the E-Motion rudder drive isn’t still a really neat idea. The system is basically a Torqeedo 4.0FP pod drive (providing roughly the power of a 10hp diesel) connected to a 5.4kWh lithium-ion battery bank and encased in the rudder itself—a true first for a cruising boat. The batteries are fitted under the berth in the aft cabin, and the engine compartment under the companionway is given over to a 4.4kW Whisper Power generator, which serves to extend the boat’s range, if necessary. The controls in the cockpit consist of a kill switch, an electronic display that toggles through various different motor performance data, and a small, low-profile throttle within easy reach of the helm.

According to Florian, Hanse had to slightly redesign the rudder of the 315 to accommodate the pod, but otherwise, the boat is the same as those equipped with a standard diesel engine. Neirich notes that Hanse worked with its rudder supplier, Jefa, on the engineering, adding, “The one stringer in the rudder was at the perfect place for the pod.”

Hanse also engineered a cover that screws on over the cavity around the pod, preserving the hydrodynamic shape of the rudder and allowing the pod to be easily accessed for maintenance and cleaning. Otherwise, the propeller is the standard Flexofold used on all the other Hanse 315s.

           The electric motor and prop are integrated into the rudder’s trailing edge   

           The electric motor and prop are integrated into the rudder’s trailing edge   

Put to the Test

Conditions were ideal on test day: plenty of sun and a good 20-knot breeze kicking up a chop on the cabbage-green waters of Holland’s IJsselmeer. We began by simply motoring down the short access canal to the marina. In these smooth waters, the boat was soon moving at 6 knots, making a noise like an egg-beater at its full throttle position. Acceleration is strong, but smooth, thanks to Torqeedo’s electronics.

Boatspeed naturally dropped in choppier waters, to around 5.1 knots at full power with the wind just off the bow. Motorsailing in the same conditions, the pod boosted our speed by about 1 knot, from 6.5 knots to 7.5 knots. Just as it would using a diesel, the extra power from the motor also allowed us to point closer to the wind without sacrificing speed.

Next, we tried reversing into the wind (with the sails furled, of course). Surprisingly, the motor on our test boat, at least, was set up to develop less than half its rated power when running astern. Nonetheless, its 1.9kW took around 15 seconds to bring us to a standstill from full ahead and was then enough to get us butting backward into the wind and the chop at 2-3 knots.

One problem I did note: putting the pod in the rudder makes the propeller the aft-most point on the boat, and liable to cavitation as the boat pitches astern. The prop’s position also poses a danger to swimmers and even those just reaching over the transom. “We are aware of this,” says Nierich, adding that the decision to position the prop where it is, resulted from that fact that it’s “a better point on the rudder in order to put less strain on the rudder bearing.”

As with a diesel engine, range drops off dramatically at higher revs—from about 15 miles at 4.5 knots of boatspeed to just 9 miles at 6 knots. The range-extending generator from Whisper Power along with a 26 gal fuel tank can give you hundreds of extra miles.

           The low-profile controls won’t catch on lines   

           The low-profile controls won’t catch on lines   

Close Quarters

Of course, what really sets an electric boat apart from its diesel cousins is its maneuverability and the fact that it supplies full torque across most of its speeds, supplying thrust more quickly than a diesel. This is doubly true of the Hanse 315, because the tiller turns the prop through a full 100 degrees of arc, creating that much more leverage with which to spin the boat.

I’d seen the videos, but it is something else altogether to feel the way she actually swings round: literally turning on the spot, so that suddenly, the prospect of maneuvering into a really tight marina berth becomes a good deal less intimidating. In fact, the reflexes of this boat mean you can wait until the last minute before putting the helm over, and that you can expect to get round much tighter corners.

My only gripe is that having lower power astern deprives you of that useful ability to really jam on the brakes. That said, there is no prop walk, and the forces on the tiller when motoring astern are low because the rudder is always exactly parallel to the wash from the propeller. As a result, the maneuverability at every point of the turn is simply outstanding.

Up in the cockpit, the small electronic throttle is flush mounted, so it can’t tangle with lines, and it has the same angular, modern design as is found on Torqeedo’s outboards. There’s a bit of feel as you nudge forward or back. However, I found the neutral lock button poorly positioned and stiff, making it harder to flick instantly from ahead to astern when maneuvering. A lock is, of course, necessary, but it wasn’t quite where I naturally gripped the lever.

Verdict

The electric revolution is coming to sailing. It may take a generation, but in time we’ll all be relying on electric propulsion, and Hanse has now positioned itself at the forefront of this movement. Torqeedo’s pod system is impressive. It gives the boat phenomenal maneuverability and eliminates the noisy, smelly chug of the diesel. On the downside, it is still relatively expensive, so you need to find a reason to spend that money. Kudos to Hanse for its pioneering efforts in the area. 

Photos and images courtesy of Hanse

May 2018

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