Alex Walker

Alex specializes in naval architecture. A graduate of Maine Maritime Academy, with a BSc in marine systems engineering design, Alex is also an associate member of the Society of Naval Architects and Marine Engineers.

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Presentation

The implications of electric motor power curves for vessel propulsion

Many prime movers are principally defined by their rated power and RPM. However, the full picture of power delivery must consider the power above and below the rated RPM. This is represented by what has come to be called a 'rated power curve' which can vary greatly between different prime mover types, such as internal combustion engines (ICE) and electric motors (EM). The effect of curve shape on vessel performance and propulsor selection can be significant, particularly for those considering EM prime movers for their vessels. This presentation will describe the differences between ICE and EM power curves, as well as discuss the implications of EM power curves for different operating modes (such as transit or towing), continuous versus peak conditions, considerations for motor overload and partial load efficiencies. A case study will demonstrate propeller selection decisions for an EM application with calculation of operational current demand.