Yacht Sea Trial Guide

A sea trial is a planned period of operation, usually after or alongside the survey, in which the buyer's technical team observes how the yacht and selected systems behave under way. It is the only stage of a purchase where propulsion, steering, stabilisation and machinery can be seen working together under realistic load.

It is an observation exercise, not a test to destruction and not a pleasure cruise.

A viewing answers whether the yacht fits the buyer. A survey examines physical and technical condition. A sea trial shows how the yacht and its systems behave in operation. Due diligence confirms title, class, tax and documents.

The sea trial complements the survey; it does not replace it. Some issues only appear under load, while others are easier to find with the yacht alongside or out of the water.

In many transactions the sea trial takes place during the survey period agreed in the purchase agreement, often after the initial onboard inspection and sometimes after a haul-out. It may also run on the same day as parts of the survey.

Sequencing varies between transactions and is set by the agreement, the yacht's schedule, weather and the survey team's advice.

A trial gives qualified observers evidence about behaviour that cannot be seen at the dock: how engines and gearboxes respond under load, whether temperatures and pressures stay within expected ranges, how steering, stabilisers and thrusters perform, and whether noise, vibration or alarms appear as conditions change.

It provides evidence for the buyer's advisers to interpret. It does not produce a verdict on its own.

Throughout the trial, the yacht stays under the authority of her captain. The captain decides what manoeuvres are safe, sets limits for conditions and traffic, and may stop or modify any part of the programme.

The buyer's surveyor and specialists observe and record. They do not take command, and the buyer should never ask crew to exceed what the captain considers safe.

On the buyer's side: the surveyor, any engine or system specialists, a technical superintendent where appointed, the buyer's broker and the buyer if they wish. On the seller's side: the captain, chief engineer and relevant crew, often with the central agent.

Numbers should be kept to what the programme needs. Insurance, safety briefings and guest limits for the trial should be confirmed in advance.

The programme is agreed in advance between the buyer's surveyor, the captain and the brokers, within what the purchase agreement allows. It typically covers departure time and location, duration, the systems to be observed, any specialist attendance, weather limits and who pays for fuel and running costs.

A written programme helps everyone understand what will and will not be observed, and why.

Specialists watch main engines and gearboxes through a range of operating conditions set by the captain, noting starting behaviour, response to throttle, temperatures, pressures, exhaust, leaks and any alarms. Readings are compared with the yacht's records and the manufacturer's expectations by those qualified to interpret them.

Engine manufacturer technicians may attend where the scope calls for it. Their findings belong in their own report.

Depending on the yacht, observation may cover shafts and propellers, pods, waterjets or diesel-electric drives. Observers note response, smoothness, vibration and the behaviour of controls and alarms. Hybrid and electric propulsion needs specialists familiar with those systems.

Generators are observed sharing load as hotel systems run: air conditioning, galley, laundry, lighting and water systems. This can show how the power management system behaves when several systems demand power at once, which is rarely visible at the dock.

Observers watch steering response, control feel, alarms and any backup or emergency steering the captain chooses to demonstrate safely. Steering gear itself is normally examined during the survey.

Stabiliser performance is often best assessed at sea, at anchor and under way where the system allows. Observers note how the yacht's motion is controlled, alarms, noise and hydraulic behaviour. Results depend heavily on sea state on the day.

Bow and stern thrusters, dynamic positioning where fitted, and close-quarters handling are observed during departure, return and any manoeuvres the captain considers appropriate. The aim is to see control and response, not to push the yacht to its limits.

Noise and vibration are noted in guest areas, crew areas and machinery spaces as conditions change. Some specialists take measurements. Unusual vibration can point to propeller, shaft, mounting or alignment issues that may need further investigation.

The surveyor may observe radar, chart systems, positioning, autopilot, communications, alarms and bridge controls in operation. Observing systems working is not the same as certifying them.

The yacht's monitoring and alarm system records what happens during the trial. Observers note alarms, their causes and how the crew responds. Alarm and engine logs from the trial can be useful evidence afterwards.

Depending on scope and what the captain allows, observation may also include deck machinery, tender launch and recovery, watermakers, HVAC and hydraulic platforms. These items should be listed in the programme rather than added on the day.

Not everything can be observed on one trial. Port rules, traffic, the yacht's operating status, crew availability and safety limit what is reasonable. Full-power running, for example, is a matter for the captain, the agreement and the specialists, not a buyer's request.

The report should record what was observed and what was not.

Weather can postpone a trial or limit what it shows. Flat calm says little about stabilisers; heavy weather may make some observations unsafe. If conditions on the day do not allow the agreed programme, the parties may agree a later date within the agreement.

The surveyor coordinates the buyer's technical observation, records findings and connects what was seen at sea with the condition survey. The surveyor does not operate the yacht.

The captain commands the yacht and decides on safe operation. The chief engineer and crew operate systems and can explain history and behaviour, which is valuable context but not a substitute for independent observation.

On larger acquisitions, a technical superintendent may attend to interpret behaviour against the yacht's maintenance history, plan future work and support the buyer's decisions. The role differs from the surveyor's, and responsibilities should be clear.

Engine, generator, stabiliser, electrical or propulsion specialists may attend where the scope calls for them. Their observations are usually reported separately and coordinated by the surveyor.

The buyer may attend to experience the yacht under way: comfort, noise, motion and atmosphere. The buyer should leave technical observation to the specialists and should not ask crew to operate systems outside the agreed programme.

Observations are typically recorded in notes, photographs, readings and alarm logs, and summarised in the surveyor's report or a separate sea trial report. Records should state conditions on the day, what was observed and any limitations.

Lund Group may summarise findings for commercial discussion but does not edit or reclassify any professional's report.

Depending on the purchase agreement, findings may lead to proceeding as agreed, the seller addressing agreed items, reconsidering terms, further investigation or, where permitted, rejection. The agreement, legal advice and the materiality of the finding decide which applies.

Not every observation is material. Yachts are complex and trials often produce minor observations.

Where an observation is unclear, the right next step may be a specialist inspection, data analysis, a yard visit or dismantling with the seller's permission, rather than guessing. The surveyor and specialists advise.

A repeat trial may make sense after weather limited the first one, after agreed repairs, or when a specific system needs more observation. Whether one is possible, and who pays, depends on the agreement.

Costs can include fuel, crew time, port and pilot fees, specialist attendance and travel. There is no standard figure. Who pays is set by the purchase agreement and should be clarified before the trial is booked.

A trial on a smaller yacht may be a few hours with a surveyor and engine specialist. On large yachts, programmes can involve several specialists, longer runs and more systems, sometimes across more than one day.

If the yacht is in a different country, the trial may need surveyor and specialist travel, local port arrangements and accommodation. Lund Group can coordinate travel, including private aviation, around confirmed dates; technical judgement stays with the professionals.

A good trial shows how the yacht behaved on one day, in those conditions, within that programme. It cannot guarantee future reliability, that intermittent faults will not recur, or that systems not observed are in good order.

It is evidence for the buyer's decision, alongside the survey, records and due diligence.

Observations can point to machinery, stabiliser, generator or control-system work that belongs in the post-purchase maintenance or refit plan. Feeding them into the first-year budget is one of the most practical uses of the trial.

Before: programme agreed in writing, specialists confirmed, weather window identified, costs and insurance clarified, safety briefing arranged.

On the day: captain in command, limitations recorded, readings and alarms logged, buyer leaves operation to crew.

After: findings received, material items understood, further investigation or repeat trial decided, legal notice requirements followed.