How voyage optimisation can reduce charter party claims

1. ETA drift rarely looks material at first. Small slippage can create significant commercial exposure.

An ETA is the output of multiple moving variables. Route, speed profile, weather, currents, vessel performance and operational instructions all influence it. Treating ETA as a fixed number from the initial passage plan allows small deviations to compound and commercial exposure to build unnoticed.

A vessel may initially appear safely inside its arrival window. A head current then persists longer than forecast. The vessel slows to avoid heavier weather. A charterer requests a different arrival profile. None of these events necessarily creates a claim by itself. The commercial risk emerges when their cumulative impact is not recalculated, understood and communicated.

ETA drift can affect:

• laycan or cancelling-date discussions;
• berth and cargo planning;
• contractual ETA notices;
• just-in-time arrival instructions;
• speed-up or slow-steaming decisions;
• delivery expectations and downstream commitments.

The commercial question is not simply, “What is the vessel’s ETA now?” It is, “Where is the voyage likely to finish under the current route and operating profile, what commercial exposure does that create, and what alternatives remain available?”

T.VOS addresses that question through dynamic route and speed calculations and a projected end-of-sea-passage view. The Dynamic Charter Party Module combines past and actual performance, current conditions and the forecast for the remaining route, then updates the expected outcome against the agreed charter terms.

Contractual process still matters. BIMCO’s Just in Time Arrival Clause allows charterers to request a speed adjustment to meet a specified arrival time, but the request, owners’ agreement, vessel capability and any effect on the cancelling date must be managed in accordance with the clause. Better ETA intelligence therefore needs to be connected to written instructions and a clear approval process.

A more accurate ETA does not reduce exposure if it stays on an operator’s screen. It reduces exposure when it triggers the right commercial decision and the right communication.

2. Speed and consumption assumptions: when planning numbers become performance disputes

Speed and consumption claims often begin before departure, when a complex performance clause is reduced to one convenient number.

A charter party may distinguish between ballast and laden conditions, specified drafts, fuel types, good-weather limits, engine modes and agreed speeds. Operationally, however, these are often reduced to a generic service speed and standard consumption curve. The risk is that the voyage is then managed against one benchmark while any subsequent performance claim is assessed against another.

Recent guidance makes the legal and evidential sensitivity clear: speed and performance disputes can depend heavily on the precise wording of the good-weather definition and the evidence available on weather conditions. The same guidance cautions that there is no universal “about” allowance that can safely be applied without considering the vessel and the charter wording.

A clause-aware optimisation process should therefore model:

• contracted speed and consumption rather than an internal estimate;
• ballast and laden performance separately;
• the vessel’s actual hydrodynamic characteristics;
• relevant weather and current criteria;
• any agreed tolerances;
• the effect of speed instructions on fuel and ETA;
• the projected position at the end of the passage.

The Dynamic Charter Party algorithm supplied by Theyr is designed to turn guaranteed speed, fuel consumption, weather exclusions and financial clauses into inputs for T.VOS’s optimisation engine. As route and speed options are assessed, the system can calculate their likely charter party implications alongside fuel, time and emissions.

Consider a vessel beginning to fall behind its assumed speed while remaining close to its fuel target. A fuel-only system may still judge the voyage satisfactory. A contract-aware system should recognise the trade-off: fuel performance may remain on target while the speed buffer erodes, increasing potential exposure against ETA or performance obligations.

The operator can then compare the actual choices:

• increase speed and accept higher consumption;
• change route to recover time;
• preserve the present route and revise the ETA;
• obtain or confirm a charterer instruction;
• accept a projected variance but document it properly.

Optimisation does not decide which party is legally responsible. It gives the desk time to choose a commercially deliberate response rather than discover the issue in a post-voyage performance report.

3. Weather deviation: good seamanship can still produce a poor claim file

Weather routing and charter party weather assessment are related, but they are not the same task.

A Master may alter course for entirely sound navigational or safety reasons. The subsequent dispute may concern whether the deviation was permitted, whether the weather was within the contractual definition, how much delay or additional consumption it caused, and whether the counterparty was informed properly.

A weak record often contains the final route and the final weather report, but not the information that mattered when the decision was taken. A more defensible record should show:

• the forecast available at the time;
• the expected conditions on the original and amended routes;
• the route or speed alternatives considered;
• the actual conditions encountered;
• the Master’s or operator’s rationale;
• relevant orders and notices;
• the effect on ETA, speed and consumption.

This distinction matters because weather sources do not always agree. Vessel logbooks and weather-routing reports can identify different good-weather periods, creating disputes over which evidence should prevail. The charter party may specify the governing source but frequently does not.

T.VOS combines metocean information with ship hydrodynamic models and route calculations. The Dynamic Charter Party Module is designed to apply live and historical weather data to compliance assessment, quantify the effect of conditions on speed and fuel consumption, and distinguish relevant good-weather and bad-weather periods.

The benefit is consistency. The weather used to plan or re-optimise the voyage can also support the operational explanation of what changed and why. That reduces the gap between the routing decision and the later performance assessment.

It does not mean that software output determines contractual interpretation. Clause wording, vessel records, quality of evidence and governing law still shape the legal analysis. The value lies in creating a clear, contemporaneous record of what happened, why decisions were made and how performance evolved—rather than trying to reconstruct that picture after a dispute has arisen.

4. Late notices: accurate information has little value after the deadline

An operator can identify an ETA change correctly and still leave the business exposed if the information is not sent to the correct recipient, in the required form and within the contractual timescale.

Notice risk can arise around:

• revised ETAs;
• delay and deviation;
• charterer speed instructions;
• port or berth changes;
• bunkering deviations;
• cargo readiness;
• just-in-time arrival requests;
• arrival and Notice of Readiness procedures.

The operational and contractual workflows must remain connected. BIMCO’s Sea Traffic Management Clause emphasises the sharing of arrival information, but also states that voyage optimisation does not remove the separate requirement to tender Notice of Readiness in accordance with the charter party’s laytime provisions.

Written instructions also matter when speed is changed. BIMCO’s Slow Steaming Clause requires charterers’ slow-steaming instructions to be given to the Master in writing, creating a contemporaneous record of what was ordered if a dispute later arises. Crucially, those instructions remain subject to the Master’s overriding responsibility for the safety of the vessel, crew and cargo.

Voyage optimisation can improve this process by identifying the event that should trigger action. An ETA variance, projected fuel exceedance or developing speed shortfall can be flagged before the commercial consequence becomes fixed. An API-first solution can also feed that information into the platform or workflow already used by the operator.

5. Poor evidence capture: the claim that nobody can reconstruct cleanly

Post-voyage disputes become harder when the relevant evidence is scattered across noon reports, email chains, messaging applications, weather files, routing reports, voyage-management systems and port documents.

The problem is rarely a complete absence of data. It is the absence of a coherent sequence.

A useful claim file should answer five questions:

1. What contractual baseline was the voyage being managed against?
2. What did the route, ETA and performance projection show at each material decision point?
3. What changed?
4. Who instructed or approved the response?
5. What was the eventual fuel, time and commercial outcome?

T.VOS-generated voyage datasets can include route, speed, ETA and ETD, power or RPM, fuel consumption and metocean parameters, with outputs available in formats including JSON, CSV and RTZ. The value of these fields is not simply that more data is retained. It is that the progression from initial plan to revised plan and final outcome can be shown consistently.

The voyage optimisation record should sit alongside, rather than replace:

• the executed charter party and recap;
• voyage and charterer instructions;
• vessel logs and noon reports;
• ETA and delay notices;
• Notices of Readiness;
• Statements of Facts;
• protest letters;
• agent and terminal communications;
• bunker and ROB records.

Why multi-objective voyage optimisation matters to claims prevention

The route with the lowest predicted fuel burn is not necessarily the route with the best commercial outcome.

A fuel-saving route may weaken ETA certainty. A faster route may increase consumption beyond a contracted allowance. Avoiding one weather system may extend distance and create a notice or delivery issue. Slow steaming may improve emissions performance while changing the basis on which speed warranties apply.

This is why charter party claims cannot be treated as a separate calculation added after the route has been selected.

T.VOS uses multi-objective optimisation to evaluate route and operating choices across objectives such as minimum fuel, best time, just-in-time arrival, TCE, CII and charter party performance. Rather than producing one supposedly perfect answer, it can produce a set of optimised alternatives showing where one objective improves and another requires a trade-off.

An owner may prefer a route that limits bunker consumption and preserves the vessel’s performance buffer. A charterer may place greater value on earlier cargo delivery, even where that requires higher fuel consumption. The Dynamic Charter Party Module is designed to present these perspectives alongside their likely commercial implications, giving both parties a more objective basis for evaluating the trade-off.

The aim is not to replace commercial judgement, but to make the available choices, trade-offs and likely consequences visible before an instruction is given, not after its impact becomes a dispute.

A practical claims-reduction workflow

Before departure: turn the charter party into operating controls

The first step is to translate the fixture into structured inputs. Speed and consumption warranties, ballast and laden conditions, weather criteria, ETA notices, laycan, deviation wording and relevant commercial clauses should not remain buried in PDFs and email chains.

Operators should then compare several voyage scenarios rather than approve one route in isolation. Each scenario should show its expected fuel, time, ETA, weather exposure and projected charter party result.

Before sailing, the team should also agree:

• who owns each notice and item of evidence;
• what amount of ETA drift requires escalation;
• what speed or fuel variance triggers review;
• when claims or commercial colleagues should become involved;
• which data source and document version form the operational baseline.

During transit: monitor where the voyage is heading

Daily monitoring should compare actual performance with the contracted basis, not only the internal voyage budget.

That means separating sea time from port time, retaining ballast and laden distinctions, classifying weather periods consistently and maintaining a projected end-of-voyage position. When a threshold is breached, the team should be able to compare revised routes and speed profiles while recovery is still possible.

The decision record should retain the projection before the change, the alternatives considered, the instruction given and the resulting forecast.

After the voyage: close the operational and evidential loop

The final reconciliation should compare the actual result with the most recent projected outcome. Material differences should be explained while the voyage is still fresh and supporting evidence remains accessible.

The completed record can then improve:

• future route and speed assumptions;
• vessel performance models;
• charter party negotiations;
• notice procedures;
• clause wording;
• operational escalation thresholds.

This is how claims prevention becomes cumulative. Each completed voyage produces a better basis for the next fixture rather than another isolated archive.

Where T.VOS fits

The Dynamic Charter Party Module, developed through the collaboration between Rensmarine and Theyr, brings charter party calculations into the T.VOS multi-objective voyage optimisation process.

Its role can be understood across three stages.

At planning, contractual speed, consumption, weather and financial terms are converted into computational inputs. Proposed routes can then be compared by fuel, time, ETA, emissions and likely charter party outcome.

During execution, actual speed, fuel and encountered conditions update the projected end-of-sea-passage position. Where the voyage is trending towards a speed claim, consumption penalty or missed commercial target, alternative route and operating choices can be assessed.

For commercial review, the platform provides a consistent operational history of the plan, changes and projected outcomes. Structured templates can be retained and reused, while the API-first architecture allows T.VOS capabilities to sit inside existing maritime platforms and workflows.