What is the object of measurement? Defining hull & propeller performance in the context of overall ship energy efficiency Kevin Logan President Hull & Propeller Components of Overall Ship Efficiency Problem: How do we separate out the parts? Hull & Propeller Components of Overall Ship Efficiency Vocabulary ClarificaIon – Efficiency vs. Performance Define: EFFICIENCY = Instantaneous KPIs (e.g. speed loss, etc.) Define: PERFORMANCE = KPIs across Ime (e.g. drydocking cycle) Hull & Propeller Components of Overall Ship Efficiency Performance – tracking KPIs across maintenance cycle Hull & Propeller Components of Overall Ship Efficiency Problem: How do we separate out the parts? Engine Efficiency RelaIvely easy to monitor separately: • 
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Fuel flow meters Engine power output (KW, BHP, SHP) Key Performance Indicator = SFOC (g/KW-­‐Hr) Specific Fuel Oil ConsumpIon (Diesel) Curves like these are available from most engine manufacturers SFOC vs. %Engine Load allows comparison of design to measured performance Monitor how efficiently engine converts fuel to power (i.e. changes from baseline) Hull & Propeller Components of Overall Ship Efficiency SeparaIng Propeller from Hull Efficiency Difficult Hull & Propeller Components of Overall Ship Efficiency Need Thrust Measurement to Separate Propeller from Hull Thrust meter must be accurate – this is an issue SeparaIng Propeller from Hull Efficiency is Difficult Propeller Efficiency: •  Propeller open water curves •  Sensor accuracy issues: thrust Thrust Coefficient: Advance RaIo: Torque Coefficient: ​𝑲↓𝑻 = ​𝑻/𝝆​𝒏↑𝟐 ​𝑫↑𝟒 𝑱= ​𝑽↓𝒂 /𝒏𝑫 ​𝑲↓𝑸 = ​𝑷/𝝆​𝒏↑𝟑 ​𝑫↑𝟒 ​𝜼↓𝟎 = ​𝑱/𝟐𝝅 × ​𝑲↓𝑻 /​𝑲↓𝑸 Propeller Open Water CharacterisIcs Propeller Efficiency: Need accurate measurements: Thrust, Power (torque), RPM, and STW Hull & Propeller Components of Overall Ship Efficiency Lacking accurate thrust measurement, Propeller & Hull Efficiency typically lumped together Typical Speed-­‐Power Curve (e.g. Ship Trials) 35000 Clean Hull/Propeller, Calm weather & sea Shag Horsepower 30000 25000 𝑺𝑯𝑷 ≈𝒄​ 𝑽↑𝟑 20000 15000 10000 14 16 18 20 22 Speed (Kts) 24 26 28 Ship & Environmental Factors EffecIng Ship Performance Propeller
Fouling
Source: Modeling of Ship Propulsion, Pedersen and Larson Hull
Fouling
Effect of Added Drag or Slip 35000 Shag Horsepower 30000 Added drag/slip from any source Clean Hull/Propeller 25000 20000 15000 10000 14 16 18 20 22 Speed (Kts) 24 26 28 Ship & Environmental Factors Cause Data Scaier Source: Modeling of Ship Propulsion, Pedersen and Larson Key Hull & Propeller Performance Problem •  Remove Effects of Varying Ship & Environmental CondiIons •  Remaining Performance DegradaIon Due to Hull & Propeller KPIs for Hull & Propeller Efficiency •  Power Increase (power penalty) •  Speed Loss •  Trends over docking cycle (performance) Power Increase @ Constant Speed 35000 Fouled Hull/Propeller Shag Horsepower 30000 25000 Clean Hull/Propeller ΔP 20000 15000 10000 14 16 18 20 22 Speed (Kts) 24 26 28 Speed Loss @ Constant Power 35000 Fouled Hull/Propeller Shag Horsepower 30000 Clean Hull/Propeller 25000 20000 15000 ΔV 10000 14 16 18 20 22 Speed (Kts) 24 26 28 Ways to Remove Ship & Environmental Effects Alternate Analysis Methods: •  Resistance Modeling & NormalizaIon •  StaIsIcal Analysis •  Data Filtering