Quasi-Propulsive Coefficient η_D
η_D = η_O · η_H · η_R - the efficiency of energy transmission from delivered power to effective (towing) power.
Quasi-propulsive coefficient η_D
0.762 -
Formula, assumptions, and limits
Typical merchants η_D 0.65–0.75. Over-propellering (high KT) tips η_O down; twin-screw lowers η_H; large rudder bulb raises η_R. Total propulsive efficiency η_T = η_D · η_S (shaft efficiency).
Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| Open-water efficiency | - | open-water chart | |
| Hull efficiency | - | hull efficiency calc | |
| Relative rotative efficiency | - | typical 0.95–1.05 | |
| Quasi-propulsive coefficient | - | result |