Recent legal developments in 2026 in underperformance (speed and consumption) claims 

Recent London arbitration awards demonstrate a continued emphasis on the construction of charterparty terms and the evidence available to the parties for assessing claims of underperformance. While tribunals continue to regard the good weather performance warranty as the primary contractual benchmark, recent decisions show a more nuanced application of earlier authorities, in particular Eastern Pacific Chartering Inc v Pola Maritime Ltd (The Divinegate) [2023] 1 Lloyd’s Rep 442. To recap, the High Court judgment in The Divinegate held that where the parties have adopted a performance warranty in a charterparty that is based expressly on good weather performance then applying that warranty will be the primary method for assessing any claim since it reflects the chosen benchmark for performance. Any alternative method must be established as reliable and consistent with the express performance warranty. 

Express warranty clauses v defects in hull or other breaches – a possible alternative method of calculation 

London Arbitration 1/26 illustrates an important development in the treatment of claims where a breach of the Charterparty (other than the warranty clause) is alleged.  

The tribunal held that substantial hull fouling at delivery amounted to a defect within the meaning of the off-hire clause.  

However, there were no good weather periods. 

Significantly, the tribunal declined to apply The Divinegate in a rigid or prescriptive manner, saying that “These propositions were excessively prescriptive in a case such as this”. Even though the contractual good weather requirement was not met (in that the “good weather” period was insufficient for the purposes of engaging the performance warranty), the tribunal accepted expert evidence based on recognised naval architectural and engineering principles to quantify the loss of time and increase in bunker consumption suffered by the vessel. In doing so, it confirmed that where a relevant defect or breach is clearly established, and its impact can be reliably demonstrated, the absence of qualifying good weather data will not necessarily defeat a claim. 

By contrast, London Arbitration 4/26 demonstrates that this flexibility is strictly limited.  

Charterers case was that the hull was fouled on delivery, causing underperformance, relying on a weather routing report using an all-weather analysis. The tribunal found that the charterers had failed to prove any meaningful fouling at delivery and therefore failed to establish a breach.  

By applying the good weather parameters there were no good weather periods, so the tribunal considered the report and what the position would have been if there had been a breach. 

In this case, the tribunal emphasised that the weather routing report did not reflect the weather impact on the vessel and did not demonstrate the loss sustained. Even if fouling had been proven, the claim would have failed on quantum due to deficiencies in the evidence.  

Taken together, these cases confirm that while The Divinegate remains influential, tribunals may be persuaded to treat it as not imposing an absolute rule where a relevant defect or breach can be otherwise established. This will probably require expert evidence, rather than just a weather routing report. 

Contractual construction 

London Arbitration 3/26 reflects a continuing focus on the proper construction of charterparty terms.  

Faced with competing definitions of good weather, the tribunal preferred the provision appearing later in the contract as representing the parties’ final intention. It further held that performance warranties are not continuing warranties unless clear words are used; they apply only at the date of the charter (or, possibly, delivery). 

The tribunal also rejected a narrow interpretation of good weather that would exclude conditions at the upper limit of the stated parameters, adopting a commercially sensible construction (“up to Beaufort Force 4 and Douglas Sea State 3” included conditions which were BF4 and DSS3.) 

Finally, it confirmed that positive currents should not be discounted when assessing performance, consistent with the position recognised in The Divinegate.  

These findings underline that issues of construction must be resolved before any technical assessment of performance can be undertaken. 

Evidence required and the burden of proof 

A consistent theme across the recent awards is the scrutiny applied to evidential material supplied. In London Arbitration 3/26, the tribunal said that the burden was on charterers to establish any “consistent discrepancy” between vessel logs and third-party data when seeking to displace the logs. Logs therefore remain the primary evidential source unless challenged in any convincing manner. 

London Arbitration 4/26 further demonstrates that not all expert or weather routing company evidence will be accorded equal weight. Reports that fail to apply contractual benchmarks, or are described as “for reference only”, are given little, if any, evidential value. In that case, the charterers’ alternative percentage-based methodology was regarded as over-simplified and insufficient to establish loss.  

These decisions reinforce that, while tribunals may consider alternative evidence, such evidence must be both reliable and contractually compliant. 

Use of third-party data and missing logs 

London Arbitration 5/26 addresses the position where evidence from the vessel’s logs is absent despite a provision in the charterparty that evidence of weather conditions was to be taken both from the logs and independent weather bureau reports. Although the vessel’s logbooks had not been disclosed, the tribunal accepted that the charterers’ expert could properly rely on noon reports and third-party weather data.  

This reflects a pragmatic approach where some potentially relevant evidence is not available, provided that the methodology adopted remains consistent with the contractual framework. The tribunal ultimately found that a qualifying good weather period existed and that the vessel underperformed during that period. 

Extrapolation 

The same award in London Arbitration 5/26 provides significant comments on the meaning of “no extrapolation” clauses. In that case, the charterparty recap contained a sentence that “NO EXTRAPOLATIONS TO BE MADE FOR WEATHER CONDITIONS OTHER THAN THOSE DESCRIBED ABOVE” after the “good weather” description. 

The tribunal rejected the owners’ argument that the clause imposed a blanket prohibition on extrapolation. Instead, it held that such provisions prevent extrapolation based on non-compliant weather conditions but do not prevent extrapolation from performance established during qualifying good weather periods. 

This approach is consistent with earlier authorities such as The Didymi and reflects the reasoning in The Divinegate. It recognises that performance warranties would be rendered commercially ineffective if extrapolation from compliant data were entirely prohibited. Accordingly, the tribunal accepted that performance established in good weather could be extrapolated across the voyage in order to quantify loss. 

The Birketts view: key themes and practical implications 

Several themes emerge from these decisions.  

First, tribunals continue to place primary emphasis on the contractual bargain struck between an owner and charterer, with detailed analysis of wording taking precedence over purely technical evidence.  

Second, while the good weather methodology remains central, it is not invariably determinative where breaches of the charterparty or defects in the hull of the vessel are established and can be quantified by reliable alternative means. 

Third, evidential rigour is critical. Parties must ensure that weather routing company reports and expert analyses adhere to the contractual criteria and are clearly reasoned. Deficiencies in methodology or failure to follow the agreed benchmarks will most likely be fatal. Finally, the treatment of extrapolation demonstrates a commercially sensible approach to interpretation and permitting its use where evidence is grounded in compliant good weather. 

In practical terms, these awards underline the importance of continued careful drafting of performance clauses that concern the speed and consumption of the vessel, including clear definitions of good weather, allocation of evidential weight between logs and third-party data, and express treatment of extrapolation. Equally, parties advancing or resisting claims must ensure that their evidential case is both sound and firmly rooted in the terms of the charterparty and any benchmark conditions that must be adhered to. 

Postscript – As the decision in 3/26 re-emphasised, the warranties are normally only given on delivery or the date of the charter. If there is no good weather to perform an assessment immediately after delivery, evidence of performance of the vessel in the immediately preceding voyage(s) could well be relevant and disclosable.