By Prokopios Krikris FCIArb, Arbitrator

Published 15 September 2026

Expert evidence is a broad subject, particularly in shipping disputes, where technical, operational and commercial issues often overlap. A good understanding of technical matters and market practice is therefore important when evaluating such evidence.

My experience with expert evidence comes from several perspectives: instructing experts while working in-house for owners and charterers across a wide range of disputes, including but not limited to cargo and engine damage, slow pumping, crane damages, underperformance, weather delays, stevedore damage and navigational issues; acting as an expert on vessel performance claims; and evaluating expert evidence as an arbitrator. My studies in naval architecture, together with practical experience attending ship repairs and damage inspections early in my career while handling several complex hull and machinery claims, also give me a useful level of technical awareness.

This paper brings together a few practical observations drawn from those experiences. Part II will go on to explore challenges to expert evidence and the lessons that can be drawn from those cases.

Expert evidence in general

Vessels and cargoes occasionally suffer damage during the maritime adventure. Disputes may also arise from many other aspects of the underlying contract. Depending on the nature of the dispute, expert evidence may be required from a wide range of disciplines: marine engineers, master mariners, cargo scientists, chemists, marine biologists, metallurgists, naval architects and other industry specialists. Commercial issues may also call for expertise in areas such as banking, accounting, trading, insurance, chartering or quantum experts.

The party wishing to rely on expert evidence must ensure that the expert has the relevant knowledge and experience. An expert’s duty is to assist the tribunal on matters within his or her expertise, and that duty overrides any obligation to the party instructing or paying the expert. Expert reports should also meet appropriate standards. Arbitration tribunals, however, are not generally bound by strict rules of evidence. In one case, for example, a tribunal did not reject an expert opinion simply because it failed to comply with CPR Part 35. The difficulty was that the expert lacked relevant experience and, rather than assisting the tribunal, appeared to argue the party’s case.

In a recent case, acting as a third-party expert, I was asked to review the parties’ positions on a performance claim. What caught my attention was that the expert report addressed “the construction of the warranty” and went on to argue how the contract should be interpreted. This attracted criticism from the lawyers, who questioned whether the expert had strayed beyond the proper limits of his expertise.

One or more experts?

The range of potential expertise is extensive. But not every dispute requires an expert, and deciding whether expert evidence is needed – and, if so, what kind – is important. Depending on the nature and complexity of the issues, a case may also require experts from more than one discipline.

Cargo damage disputes are a good example. They may require evidence from a weather expert or master mariner on the conditions encountered during the voyage, together with evidence from a cargo scientist on the nature and likely cause of the damage.

I recently dealt with two major cargo damage disputes where a combination of expertise was required. The owners relied on heavy weather encountered during the voyage as a defence. Weather experts and mariners considered the conditions en route, while cargo scientists who attended the vessels during discharge considered the condition and likely cause of the cargo damage. Their evidence also had to be considered alongside that of locally appointed court surveyors, who concluded that water ingress had caused the damage. The owners’ surveyors disagreed. If the disputes proceeded to arbitration, the tribunal would have to weigh the competing evidence and reach its own conclusions.

In one of those cases, the master had issued a note of protest recording heavy weather and stating that the vessel had altered course to reduce its effects. The weather experts, however, presented a different picture. They concluded that the vessel had not altered course as stated and considered the vessel’s low recorded slip inconsistent with the alleged heavy weather. Independent weather data also indicated normal conditions, consistent with the reported low slip.

Covid-19-related disputes provide another example of expertise becoming relevant. Medical experts were called upon to consider the protocols followed on board and, by reviewing the crew’s symptoms and medical records, to assess when Covid-19 was likely to have been introduced onto the vessel. The answer could be important in determining responsibility between owners and charterers.

In one case, the vessel stopped en route to the discharge port to take on supplies and carry out a crew change. Several days after arriving at the discharge port, a number of crew members developed Covid-19 symptoms. The vessel was placed in quarantine, and the charterers claimed that she was off-hire and sought damages. The key question was when the virus had been brought on board. If this occurred during the intermediate stop and crew change, it could point towards a matter for the owners; if it occurred during the stay at the discharge port, the position could be different. Both parties therefore relied on medical experts, making the timing and likely source of the infection an important part of the evidence.

Industry practice

Expert evidence can also be relevant in establishing industry custom or practice. Moreover, expert evidence is “commonly adduced to prove the meaning of a technical term in a document (such as a will or a contract) and sometimes even to demonstrate that a seemingly ordinary word in a document has an unusual meaning in the context in which it was used”.1

Speed and performance claims are a good example, where evidence of industry practice in assessing a vessel’s performance may assist in determining the meaning and effect of the benchmark conditions against which to measure performance (see eg “good weather days”). A person with specialist knowledge and experience in analysing vessel performance may have the necessary expertise to give such evidence; the expert does not necessarily need to be a master mariner or marine engineer.

Similarly, in disputes concerning additional piracy or war-related costs, an insurance broker or someone with substantial day-to-day experience in the insurance market may be able to give evidence on applicable insurance rates and market practice.

Parties may also rely on expert evidence as to market practice where it forms part of the relevant background to the interpretation of contractual terms (see Crema v Cenkos Securities plc).2 In The Divinegate,3 for example, the court considered expert evidence and previous arbitration awards when addressing the meaning of “no adverse currents”. In other cases, parties may rely on evidence from weather-routing companies to support an alleged industry practice or the meaning attributed to particular charterparty terms. Some arbitrators, however, may be slow to accept such evidence as a guide to contractual interpretation.

The opposite question is equally important: when is expert evidence not necessary?

Many maritime arbitrators have considerable technical and industry experience of their own. In London Arbitration 13/974 the tribunal observed that speed and consumption disputes were generally routine matters with which arbitrators had considerable familiarity, and that lengthy submissions and detailed expert reports were rarely appropriate. Much the same can be said today.

Timing and proportionality also matter. I encountered this in an underperformance claim involving hull fouling, where I acted as a consultant. The initial question was whether a marine biologist should be instructed to review the hull inspection reports and assess the added resistance caused by fouling and its impact on the vessel’s performance.

At that stage, I considered it unnecessary. The underwater inspection report, engine logs, reported weather and engine parameters, together with the weather-routing company’s detailed performance report, already provided sufficient information to assess the vessel’s performance. Instructing an expert would have added cost and delay without necessarily assisting the negotiations. The claim was ultimately settled at minimal cost.

The example illustrates a simple point: expert evidence can be extremely valuable, but it should be obtained when it is needed. This is particularly important in smaller claims, where the cost of instructing an expert may be disproportionate to the amount in dispute.

The range of experts and disciplines that may be relevant to shipping disputes is too extensive to examine fully in this paper, so I hope readers will forgive me for limiting myself to just a few examples.

Observations from practice and cases

• It is generally recognised that arbitrators have great freedom to determine the admissibility of evidence and weigh its probative value in light of the case’s circumstances and the parties’ arguments. (See “Reflections on Speed and Performance Claims (Part I)”.5)

• It is for the tribunal to decide what weight to give expert evidence. A tribunal may reject an expert’s opinion and reach its own conclusion based on the evidence and its experience (see London Arbitration 23/21 6 and London Arbitration 15/23 7). But “[w]here the members of the tribunal draw upon a particular piece of specialist knowledge which is in conflict with evidence they have heard, they should draw this to the attention of the parties”.8

• Choosing the right expert is important, but so too is having a decision-maker with sufficient technical and industry understanding to assess that evidence. “In some instances, tribunals will make different findings by examining the totality of the evidence before them, an ordinary procedure of the arbitral process.”9

• An expert can sometimes hurt rather than help a case. In navigational disputes involving deviation or decisions taken in heavy weather, for example, the expert’s experience with the relevant type of vessel may be important.

• Experts may give evidence concurrently, commonly known as “hot-tubbing”. Where their positions are far apart and the process is unlikely to narrow the issues, however, it may simply add time and cost. In a recent case, the tribunal decided not to allow this process.

• Opinion evidence from recognised industry organisations has been adduced in a number of laytime cases in both London and New York arbitrations. Some tribunals have accepted such evidence, while others have declined to do so.

• Where one party relies on expert evidence, the other may need its own expert if it wishes to challenge that evidence (see London Arbitration 7/1510). In London Arbitration 1/26, 11 the charterers relied on evidence from a marine engineer, while the owners called no expert evidence to challenge his findings.

• Expert evidence is not always necessary. In an SCP dispute (London Arbitration 16/2112), the tribunal was able to reach its decision on the limited evidence before it, without expert evidence on the likely rate of fouling before and after cleaning and during the port stay.

Conclusion

Expert evidence can strengthen or weaken a case. The key is knowing what evidence is needed and when to use it, whether in negotiations or arbitration.

Part II of this series will look at cases where expert evidence was challenged and the lessons that followed.

By Prokopios Krikris, FCIArb, consultant and arbitrator