WNI Official Performance Auditing
Charter Party Speed & Consumption Clauses
Ambiguous charter party terms, such as references to the Douglas Sea Scale, can lead to costly and protracted disputes. Drawing on its experience reviewing thousands of agreements, Weathernews proposes the following standardized clause to reduce ambiguity and help prevent disputes:
Getting the good-weather provisions right to reduce disputes
The speed and consumption clause is one of the most commercially significant — and most frequently disputed — provisions in any time charter. In practice, most disputes trace back to a small number of avoidable drafting gaps, above all in how “good weather” is defined and assessed. The considerations below help Owners and Charterers produce a clause that is commercially fair, technically verifiable, and resistant to dispute.
1. The Warranted Speed
- Basis: State whether performance is assessed on Speed Over Ground (SOG) or Speed Through Water (STW). Most modern clauses use SOG with a separate current correction — confirm which applies.
- Loading condition: Specify whether the warranted speed applies laden, in ballast, or both.
- Power/RPM: If the warranty is defined at a stated shaft power or RPM, say so and ensure it is verifiable from noon reports.
- “About”: Define the tolerance expressly (commonly −0.5 knots on speed). An undefined “about” is a leading cause of arbitration.
2. The Fuel Consumption Warranty
- Fuel type and grade: Identify each fuel covered (VLSFO, LSMGO, etc.) with sulphur content, consistent with IMO 2020 / CII.
- Consumption at warranted speed: State the figure for each fuel type, in good weather.
- “About” tolerance: Define expressly (commonly ±5%).
- Scope: Confirm whether the warranty covers at-sea performance only, or also addresses port and idle consumption.
3. Defining “Good Weather” — The Most Contested Term
- Avoid the Douglas Sea Scale as a standalone measure — it is difficult to derive objectively. Use numerically defined, independently verifiable parameters.
- Wind: State a maximum Beaufort Force (e.g., up to and including BF4), appropriate to the vessel’s size and trade.
- Wave: Add a Significant Wave Height limit — wind force alone misses swell. Where a Douglas Sea State is referenced, bracket it with the intended metre range (e.g., “0.5–1.25 m”) so the numeric limit governs; clearly define the wave type, i.e., wind driven waves.
- Swell: For ocean trades, consider a separate “no negative influence of swell” criterion, and clearly define what constitutes a “negative influence” of swell.
4. Good-Weather Period Assessment
- Classification: State expressly how a period is classified (e.g., good weather prevailing for more than half the period), rather than leaving it to inference.
- Reporting basis and time zone: Confirm noon-to-noon reporting if full steaming days are intended for assessment.
- Exclusions: List periods excluded from assessment — off-hire, stoppages, port approaches/departures, canal and strait transits, Charterers’-ordered slow steaming, and adverse-current periods.
- Minimum duration: If agreeing to a minimum continuous good-weather period, clearly stipulate how the minimum period shall be defined (e.g., 24 consecutive hours) so brief lulls are not treated as representative.
5. Ocean Current Adjustment
- Favourable current should not inflate the vessel’s assessed performance; absent express charter party wording to the contrary, the current factor should be negated in line with established English law (The Divinegate, 2022).
- Current factor: If STW is preferred by the parties, the CP must stipulate to apply a current correction to strip current effects from the good-weather SOG, addressing both favourable and adverse currents.
6. Statistical Representativeness
- Minimum sample: If a minimum good weather sample is required by the parties for assessing performance, clearly define how such a quantum shall be defined (e.g., a stated percentage of sea-passage time) before a performance assessment is made.
- Fallback: Agree in advance how voyages — or short coastal legs — that cannot meet the threshold are treated.
7. An Agreed, Binding Data Source
- Single provider: Nominate one genuinely independent provider whose voyage analysis (weather, wave, and current) is accepted as binding on both parties.
- Purpose: This removes the scope for parallel, contradictory expert reports on the same voyage — a leading predictor of protracted disputes.
- Standard: The provider should be independent of both parties and operate a transparent, scientifically grounded methodology.
8. Calculation Methodology & Offsetting
- Basis: Assess performance on good-weather periods (and if current-corrected), against the warranted speed less the “about” tolerance; the good-weather result is then extrapolated to the full voyage unless the charter party prohibits extrapolation.
- Formulae: Define the time-loss and excess-consumption calculations and the route-distance basis used for quantification.
- Offsetting: Provide for time loss to be offset against any consumption savings on the same voyage, and state whether performance is assessed voyage-by-voyage or aggregated over the charter.
9. Scope, Duration & Hull Condition
- Duration: Confirm if the warranty applies throughout the charter (i.e., continuing warranty).
- Maintenance and dry-dock: Consider whether a fresh performance baseline applies following dry-docking or major repairs.
- Hull fouling: Address the treatment of fouling, including the applicable methodology where the hull is fouled (for example, all-weather performance corrected by weather and current factors), and how pre-/post-cleaning baselines are handled.
How We Can Help
Weathernews Inc. has provided independent, third-party vessel performance auditing to Owners, Charterers, and P&I Clubs for decades. Our analysts, meteorologists, and oceanographers can review your draft speed and consumption clause — whether you represent Owners or Charterers — and provide technical guidance on the good-weather definition and methodology, tolerances, current treatment, data source, sample thresholds, and calculation basis, helping ensure the clause reflects your commercial intent and minimises exposure to disputes.
Contact us
Outlook
Get comprehensive fleet status insights and safeguard your vessels from unforeseen risks.
Planning
Optimize your voyage planning, enhance CII ranking, aligned with real-time insights for more efficient operations.
Underway
Enhance fleet schedule, monitor voyages with live data for better precision in maritime operations.
Analysis
Maximize the performance of your fleet using insights: emissions, routes, operations for smarter and more strategic decisions.
Optimizing fleet performance while enhancing safety, efficiency and environmental responsiveness is key to ensuring successful and profitable operations; Weathernews' technology helps us get there.
Helge Røttingen
Performance Manager, Saga Welco
Over the years, Weathernews has tailored platforms for our needs, optimizing voyage performance, monitoring CII ratings, and enhancing fuel efficiency. Their educated team ensures high standards.
Captain Ahmet Gider
Operations Manager, Transoba Shipping
Weathernews' services provide a quick overview of vessels' CII/environmental status, enabling proactive projections for informed commercial decisions when considering new employment for our fleet vessels.
Captain Stelios Dimopoulos
Operations Manager, Iolcos Hellenic Maritime Enterprises
Learn how to make better decisions with SeaNavigator
