Outboards – World's Most Powerful & an Eco-friendly Battery-powered Alternative

By George Backwell at March 13, 2011 05:19
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"The most powerful outboard in the world" claimed newish U.S. company Seven Marine when they unveiled their 557 hp outboard at the NMMA Miami International Boat Show last month. The all aluminium 6.2 liter supercharged V8 engine was sourced from GM where it normally growls under the hood of the Cadillac CTS-V sports sedan. Obviously a gas-guzzler, it seemed an interesting idea to juxtapose here Seven Marine's mutation of the 557 beast against an outboard from German manufacturers 'Torqeedo' which also employs cutting-edge technology to attain entirely different goals. First the big fellow that promises to push power boaters back in their seats when they open up the throttle.

The Seven Marine 557 Outboard


(Photo courtesy of Seven Marine)


The basic premise that led to the adaptation of this auto engine for marine propulsion was that a pair of these powerful outboards would achieve the same performance for a 45-ft powerboat as would require the fitting of four 300-hp outboards, offering considerable saving in weight, and of course drag, with only half that number of gearcases in the water. This big outboard weighs in at 1000 lbs, with a hinged top cowl covering the horizontally-mounted GM V8 unit, re-engineered by Seven with twin-pinion gears to make the necessary right-angled turn to mate with the propellor drive shaft.

Additions to the well-proven Cadillac V8 auto engine have been kept to a minimum, with the exception of a corrosion-proof stainless steel exhaust system. In association with ZF Marine the 557 offers a CAN-bus enabled disc-clutch mechanism that enables smooth, computer-controlled shifting together with a  joystick controller. Integrated power steering designed by Latham Systems adds the finishing touch to a roughly $70,000 package.

Torqueedo Cruise 4.0 RS Electric Motor Outboard

(Photo courtesy of Torqueedo)

This Germany-based international company's slogan might be, 'Power corrupts; absolute power corrupts absolutely', for they are committed to provide light weight pollution-free clean boating with their range of battery-powered outboards. Their 4.0 RS model would be ideal for the 'green-minded' cruising sailboat owner, who needs a reliable engine to navigate through a crowded anchorage or to make port against an unfavrorable tide or headwind.

Today's electric outboard engine has come a long way: Torqueedo's new 2011 models have maintenance-free brushless DC motors with rare earth magnets (six times the field strength and torque of ordinary magnets) giving increased efficiency and load/speed management. The batteries are not lead/acid type but lithium-based, which is currently the most powerful energy carrier available; rechargeable too by squeaky-clean solar power. (It would seem prudent to carry on board spare batteries in case of the need to increase running time).
Operational performance of this particular 9.9 hp model, designed for motorboats and sailboats up to 4 tons, when fuelled by a pair of Torqueeda Power batteries (according to the manufacturer) is as follows:

  • At slow speed (3 knots) 8 hours run time
  • At half-throttle (4.5 knots) 3 hours run time
  • At full-throttle (6 - 11 knots) 1 hour 10 mins run time

An ingenious remote throttle display gives constant readout of battery charge status, with (GPS enabled) speed over the ground and remaining range, as well as input power. And the price? Including batteries – around $4000.


















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