Ballast/Laden Conditions 

The ship's state when it is either empty (ballast) or carrying cargo (laden).

Benchmark Conditions –

Pre-agreed weather and sea state parameters for evaluating performance

Bunker Consumption

The amount of fuel consumed by a vessel, usually measured in metric tonnes per day (mt/day). It is a critical metric in assessing vessel efficiency and compliance with charterparty warranties.

Charterparty (C/P)

A maritime contract between a shipowner and a charterer outlines the terms of vessel hire, including performance obligations, payment, and liabilities.

Clause 8 / 15 / 17 (NYPE 1993) as referred to in Case Study PANAMAX TRADER

• Clause 8 – Owners’ obligations on vessel performance and time use.

• Clause 15 – Off-hire provisions, including causes for hire suspension.

• Clause 17 – Deductions from hire due to deficiencies or non-performance.

Deduction Clause 

Charterparty provision allowing deductions from hire for specific breaches.

Douglas Sea State (DSS)

An obsolete sea-state code, abandoned by the UK Admiralty around 1941, is still referenced in charterparties to describe sea conditions, such as DSS3. It is often confused with WMO Table 3700, the current internationally recognised sea-state code that employs different code numbers compared to Douglas. For instance, DSS 3 denotes a ‘Moderate’ sea, with a wave height range of 2 – 5 feet. The WMO Table 3700 equivalent for a ‘Moderate’ sea is Code 4, which has a wave height range of 1.25 – 2.5 m. The primary difference between the two codes is that Douglas pertains to wind waves alone, while Table 3700 reports the total state of agitation of the sea resulting from wind, swell, and the angle between swell and wind. WMO Table 3700 Code 3 describes a ‘Slight’ sea with a wave height range of 0.5 – 1.25 m. See UPC Part II for a fuller discussion.

Exclusion-by-Stealth

A term used in contract law to describe a clause that effectively excludes liability, but does so in a subtle or disguised manner, rather than in clear and express terms. In charterparties, a performance warranty may be formulated so narrowly—for example, being assessable only in “good weather” defined as Beaufort Force 4 or less, with no adverse currents and other strict limitations—that no qualifying weather actually occurs during the voyage. This creates a performance obligation that cannot realistically be tested, rendering it illusory. While the clause masquerades as a warranty, it functions as an exclusion—it prevents any realistic claim for underperformance. Because it does not state, “the owner shall not be liable,” it avoids scrutiny as a formal exclusion clause.

Courts and arbitrators may treat “exclusion-by-stealth” clauses with suspicion, applying stricter interpretation, especially under:

• The contra proferentem rule (ambiguities are construed against the party seeking to rely on the clause).

• UCTA 1977 (if relevant) or other statutory or common law controls on unfair contract terms.

Fouling 

The build-up of marine growth on the hull and/or propeller that impacts performance.

Good Weather

Contractually defined conditions in which wind and sea conditions meet contractual criteria (e.g., Beaufort scale 4 and below, DSS3) employed to evaluate performance.

Hindcast Data

Weather data reconstructed from satellite and model records used to estimate past conditions. This information helps to verify logbooks and performance claims.

Logbooks

Official onboard records are kept by ship officers that document navigation, weather, engine performance, and operational events. SOLAS, STCW, and flag state law mandate these.

Legal Significance:

Logbooks serve as primary evidence in disputes concerning speed, consumption, off-hire, and seaworthiness. Courts and arbitrators typically accept logbooks unless someone convincingly impeaches them.

Tribunal Insights:

• In London Arbitration 32/22, logbook entries were admitted despite being "subjective and crude estimates".

• In The Bertina (SMA 3144), 500+ altered entries led to the logbook being rejected as unreliable.

• In The Golden Shimizu (SMA 2991), logbooks were considered reliable unless there was proof of “obvious or wilful inaccuracies.”

Practical Notes:

• Inconsistent or vague entries can undermine a party’s position.

• Correlation with AIS, ECDIS, and hindcast data enhances evidential value.

• Alterations, omissions, or falsifications can discredit an entire record set.

MCR% (Maximum Continuous Rating)

The percentage of a ship engine’s maximum sustainable output being used. A higher MCR% typically indicates the engine is working harder to maintain speed.

Off-Hire

Periods during which a vessel is not earning hire due to issues such as mechanical failures or delays caused by the owner.

Performance Claim

A claim by charterers alleging that the vessel did not comply with contractual speed and fuel consumption warranties.

Propeller Slip (apparent)

The difference between the theoretical and actual distance travelled per propeller rotation.

Reasonable Grounds Model (RGM)

A legal and evidential framework for assessing ship performance, emphasising structured data, objective standards, and principles of English law.

Sea Trials 

Tests carried out on a vessel to verify operational performance.

Significant Wave Height (SWH)

A measure of sea conditions that represents the average height of the highest one-third of waves over a given period, usually 10 minutes.

Specific Fuel Oil Consumption (SFOC) 

It measures a ship's engine efficiency by indicating the amount of fuel (in grams) consumed per kilowatt-hour (g/kWh) of power produced. This metric reflects the engine’s performance under specific operational conditions. A lower SFOC signifies better fuel efficiency. SFOC varies with engine load, typically being lowest near optimal load and increasing at low or high loads. It is essential for voyage planning, emissions control, and assessing engine health.

Speed Warranty

An owner’s contractual promise that the vessel will achieve a specified speed under defined weather and sea conditions.

STCW / SOLAS

International conventions governing safety (SOLAS) and crew training/logbook keeping (STCW).

Voyage Analysis 

Assessment of a vessel’s voyage against its guaranteed performance metrics.

Weather Routing Company (WRC)

A third-party organisation providing weather forecasts and routing advice to the master, along with performance assessments, often scrutinised for bias or lack of evidential reliability.