Calculates ship power (kW) using the propeller law.

calcPropPwr(
  totalInstalledPwr,
  shipSpeed,
  refSpeed,
  serviceMargin = 15,
  n = 3,
  refSpeedType = "serviceSpeed"
)

Arguments

totalInstalledPwr

Total installed main engine power (vector of numericals, kW) (maximum continuous rated power)

shipSpeed

Ship actual speed (vector of numericals, m/s) (see calcSpeedUnitConversion)

refSpeed

Reference speed of the ship (service speed or maximum speed) (vector of numericals, m/s)

serviceMargin

A service margin to account for weather and sea effects:

  • Coastal operations = 10

Can supply either a vector of numericals, a single number, or rely on the default

n

Exponential relationship applied to the ship speed ratio (dimensionless). Default = 3. This argument is not vectorized, so supply a single number or rely on the default

refSpeedType

Indicates if the reference speed is service speed or maximum speed:

  • "serviceSpeed (Default)"

  • "maxSpeed"

Can supply either a vector of strings, a single value, or rely on the default.

Value

power (vector of numericals, kW)

Details

Ship speed and actual draft are typically obtained from sources such as AIS messages or ship records.

serviceMargin = 10 or 15, based on IMO (Prpic Orsic and Faltinsen, 2012). 15 indicates 15% increased resistance in at-sea water conditions, and 10 indicates 10% increased resistance in coastal water conditions.

Note that service margin is treated as an added resistance here (instead of as a reduced efficiency) to maintain consistency with the other power models used in this library. (See MAN, 2011).

References

EPA. 2009. "Regulatory impact analysis: Control of emissions air pollution from category 3 marine diesel engines." Ann Arbor, MI: Office of Transportation and Air Quality. US Environmental Protection Agency.

MAN Energy Solutions. 2011. "Basic Principles of Propulsion."

See also

Examples

calcPropPwr(totalInstalledPwr = 9363, shipSpeed = seq(10,14,1), refSpeed = 15, serviceMargin = 15, n = 3)
#> [1] 2649.858 3526.961 4578.955 5821.739 7271.211