Direct Electric Propulsion
Originally created on April 17 2008
By direct electric propulsion we mean the diesel propulsion unit is replaced by an electric motor. Under this configuration we identify two types of propulsion systems, Diesel Electric and Hybrid Electric. Fischer Panda is the ideal company to illustrate these two configurations as they build and integrate both systems under the trade name of Whisperprop.
Before going into the details of these two configurations a quick overview of Sean Seamour III specifications is warranted :
Our test bed for new technologies is thirty years young and in need of some rejuvenation work under way. After lying loveless and covered with moss in the harbor of Cherbourg for many years, other than a few quarter sized patches of osmosis where the gel shield was likely botched her hull is perfect and now splashed with a new Coppercoat epoxy bottom.
Here are the main specs:
LOA 10.2m 33.5ft (excluding bowsprit)
LWL 8.6m 28.2ft
Beam 3.2m 10.8ft
Draught 1.6m 5.3ft
Displacement 7.5metric tons
Ballast 2.0 metric tons
The engine is the old marinsed Ford tractor NG2712E
Output is 80hp/2400RPM
Continuous output is 72hp/2500rpm (52.9KW 41.6RPS)
Maximum torque overloaded 29.1kpm/1600RPM 186lbf / 26.7RPS
Gear box is a Borg-Warner 10-17-010 with a reduction ration of 2.2:1
The prop: it is a fixed three blade 22″ diameter with a high pitch of 16, left rotation from stern not that is should matter for an electric drive but I suspect ideal for regenerative sailing that an electric drive should be able to provide.
Generally, the electric drive motor to replace an internal combution engine (ICE) is rated at 1/3 to 1/4 the size of a diesel engine. This is because the ‘rated horsepower’ let alone torque of an internal combustion engine isn’t reached until it’s well up in the its RPMs, whereas an electric motor delivers its rated power practically from zero and usually well beyond the point where an ICE red-lines.
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