Service Allowance - Added Resistance
Service allowance (or "sea margin") applied to trial-condition power to reach design contract - covers weather, fouling, and ageing.
Service-condition power
8,850kW
Formula, assumptions, and limits
Typical 15–25 % for Atlantic/Pacific routes; up to 35 % for North Sea / North Atlantic winter. Cleaner hull and propeller reduce s over time - track via ISO 19030.
Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| Trial power at design speed | kW | sea trial | |
| Service allowance | - | company policy |