Machinery, Engines & Generators

MACHINERY REFIT CONTROL CHECK

The Project Manager should maintain visibility of:

• equipment description

• manufacturer

• model

• serial number

• running hours

• service history

• agreed scope of work

• manufacturer recommendations

• specialist contractor

• planned dismantling date

• condition before dismantling

• measurements and inspection findings

• parts requiring renewal

• additional work identified

• quotation or variation approval

• parts availability

• long-lead components

• lifting requirements

• foundation condition

• mount condition

• alignment requirements

• reinstatement status

• oil and fluid specification

• cooling-water readiness

• electrical and control-system readiness

• start-up procedure

• commissioning results

• load-test results

• defects and corrective actions

• service report

• warranty documentation

PRE-DISMANTLING CONDITION ASSESSMENT

Before major machinery is dismantled, the Project Manager should establish as much information as reasonably possible about its existing condition.

Where access and equipment design permit, the specialist subcontractor should carry out a non-invasive or minimally invasive internal inspection before the overhaul scope is finally authorised.

Borescope Inspection

For engines, generators, gearboxes and other suitable machinery, a borescope inspection can provide valuable evidence of internal condition without immediately committing the project to complete dismantling.

Depending on the equipment and available access points, the inspection may examine areas such as:

• cylinder condition

• piston crowns

• combustion chambers

• valve condition

• cylinder liners

• turbocharger components where accessible

• gears and internal gearbox components where accessible

• signs of corrosion

• deposits or contamination

• scoring or abnormal wear

• evidence of overheating

• foreign-object damage

Photographs, and video where useful, should be taken during the inspection so that the findings are supported by recorded evidence rather than only a verbal assessment.

SUBCONTRACTOR CONDITION REPORT

Following the preliminary inspection, the specialist subcontractor should produce a written report before major dismantling is authorised.

The report should identify:

• yacht and equipment identification

• manufacturer and model

• serial number

• running hours where applicable

• reason for inspection

• inspection method

• areas inspected

• areas that could not be inspected

• photographs of the internal condition

• defects or abnormal conditions identified

• specialist's technical assessment

• recommended scope of work

• parts expected to be required

• known exclusions or assumptions

• quotation for the proposed work

• anticipated duration

• parts lead times where known

• expected machinery downtime

The report establishes the technical basis for the proposed overhaul and provides a record of the condition identified before major dismantling begins.

PROJECT MANAGER REVIEW & OWNER REPORT

The subcontractor's report should not simply be forwarded to the Captain or Owner without review.

The Project Manager should assess the findings, discuss them with the Chief Engineer where appropriate and prepare a concise project report for the Captain, Owner's Representative or Owner.

The PM report should clearly explain:

• why the machinery was inspected

• what the specialist found

• the supporting photographic evidence

• the proposed scope of work

• whether the proposed work appears consistent with the findings

• estimated cost

• programme duration

• parts availability and lead-time risks

• effect on the overall refit programme

• operational consequences

• any significant alternatives available

• any decisions required from the Owner's side

DECISION MEETING & AUTHORITY TO PROCEED

The Project Manager should then hold a review meeting with the Captain, Owner's Representative or other authorised decision-maker before releasing the major overhaul work.

The specialist may also attend where detailed technical explanation is required.

The meeting should establish:

• accepted technical scope

• agreed exclusions

• approved budget

• agreed programme

• parts procurement authority

• reporting requirements

• required manufacturer or Class involvement where applicable

• authority to proceed with dismantling

Once the agreed scope has been authorised, dismantling and detailed overhaul can begin.

STRIP-DOWN INSPECTION & CONDITION ASSESSMENT

The original quotation for a machinery overhaul is often based on known symptoms, service intervals and accessible inspection.

Once the equipment is dismantled, additional wear or damage may become visible.

The Project Manager should therefore treat strip-down as an inspection stage rather than assuming that the original scope will remain unchanged.

Depending on the machinery, inspection may include:

• bearings

• shafts

• journals

• seals

• pistons and liners

• cylinder heads

• valves

• turbochargers

• pumps

• heat exchangers

• gears and couplings

• engine mounts

• corrosion

• contamination

• abnormal wear patterns

• evidence of overheating

• previous repairs

Measurements

Where dimensional inspection forms part of the overhaul, the results should be recorded rather than relying only on the technician's verbal assessment.

Measurements may include:

• clearances

• wear limits

• shaft dimensions

• bearing condition

• cylinder or liner measurements

• end float

• alignment readings

• other manufacturer-specified tolerances

The measured condition should be compared with the applicable manufacturer's limits or approved technical criteria.

ADDITIONAL WORK & VARIATION CONTROL

Machinery overhaul frequently generates additional work after strip-down.

A specialist may discover that components originally expected to be reused are outside tolerance, damaged or approaching the end of their serviceable life.

The Project Manager should not allow significant additional work to proceed automatically without establishing the technical reason, programme effect and commercial consequence.

When Additional Work Is Identified

The PM should establish:

• what defect has been found

• where it is located

• how the defect was identified

• the relevant measurement or inspection result

• the manufacturer's permitted limit where applicable

• whether the component can be reused

• whether repair is technically acceptable

• whether replacement is recommended

• parts availability

• lead time

• cost

• programme impact

• effect on warranty

• effect on related machinery

The finding should be supported by photographs, measurements or a specialist report where appropriate.

TECHNICAL FINDING → COMMERCIAL DECISION

A machinery defect is first a technical issue, but it may quickly become a commercial and programme decision.

The Project Manager should convert the technical finding into information that allows the Captain, Owner's Representative or authorised decision-maker to make an informed decision.

A clear variation should normally state:

• original scope

• additional defect found

• proposed corrective action

• reason the work is required

• parts required

• additional labour

• additional cost

• programme impact

• technical consequences of not carrying out the work

PARTS, COMPONENTS & TRACEABILITY

Replacement parts should be identified against the correct machinery model, serial number and manufacturer specification.

Where appropriate, the PM should confirm:

• manufacturer part number

• equipment serial number

• original equipment or approved-equivalent status

• quantity

• delivery date

• certification where required

• warranty conditions

• storage requirements

• preservation requirements

Removed Components

Components removed during overhaul should be controlled so that serviceable parts are not lost, mixed between machinery units or accidentally discarded.

For major machinery work, a simple component-identification system can be used to record:

• equipment identification

• component description

• removal date

• condition

• inspection result

• repair or replacement decision

• storage location

• reinstatement status

OFF-VESSEL WORKSHOP REPAIRS

Major components may be removed from the yacht and sent to an external workshop for overhaul, machining or specialist testing.

The Project Manager should maintain traceability from removal through return to the vessel.

This should include:

• component identification

• photographs before dispatch

• serial numbers

• condition at removal

• agreed workshop scope

• transport arrangements

• workshop inspection report

• additional findings

• authorised variations

• repair report

• test results

• return date

• condition on return

• warranty documentation

This prevents a major component leaving the yacht as an unidentified item and returning later with little evidence of what work was actually carried out.

MACHINERY REMOVAL & LIFTING

Removal of a main engine, generator, gearbox or other major machinery unit should be treated as a planned lifting operation rather than simply another subcontractor task.

Before removal, the Project Manager should establish how the machinery will move from its installed position to the workshop or transport point.

The planning should consider:

• machinery weight and centre of gravity

• certified lifting points

• lifting equipment and safe working load

• chain blocks, hoists, beams or temporary lifting structures

• deck and structural loading

• access route

• removal of hatches, doors, panels or temporary structure

• clearance through machinery-space openings

• pipe, cable and control-system disconnection

• protection of surrounding equipment

• temporary supports

• crane position and reach where applicable

• weather restrictions for external lifts

• exclusion zones

• lifting plan and risk assessment

The lifting operation should be controlled by suitably competent personnel using equipment appropriate to the load and operation.

DISCONNECTION & IDENTIFICATION

Before machinery is physically removed, all connected services should be isolated, disconnected and clearly identified.

This may include:

• fuel supply and return

• lubricating-oil systems

• seawater cooling

• freshwater cooling

• exhaust system

• electrical power

• control wiring

• sensors and alarms

• hydraulic connections

• compressed-air connections

• gearbox or propulsion connections

Identification should be sufficiently clear that the system can be reinstated correctly even if different personnel carry out the reinstallation several weeks later.

Photographs taken before disconnection are particularly valuable for complex installations.

FOUNDATIONS & ENGINE MOUNTS

Removal of machinery provides an opportunity to inspect areas that are normally hidden beneath the equipment.

Before reinstallation, the machinery foundation should be inspected for condition and suitability.

The inspection may include:

• corrosion

• cracking

• damaged welds

• loose or damaged fasteners

• deterioration of mounting surfaces

• contamination by oil or fuel

• previous repairs

• condition of chocks or shims

• condition of resilient mounts

• evidence of abnormal movement

Resilient Mounts

Where engines or generators are installed on resilient mounts, the condition and specification of the mounts should be checked before the machinery is returned to service.

Mounts should not automatically be reused simply because they remain physically intact.

Age, compression, deterioration, contamination and unequal loading can affect machinery position and vibration behaviour.

MACHINERY CHOCKING, PROPULSION ALIGNMENT & VIBRATION CONTROL

Installation and alignment of main engines, gearboxes and propulsion machinery is a specialist activity requiring accurate measurement, controlled adjustment and documented acceptance.

The Project Manager should understand the complete propulsion alignment chain rather than considering the engine, gearbox and propeller shaft as separate items.

A typical propulsion train may include:

• main engine

• resilient engine mounts or machinery chocks

• reduction gearbox

• flexible coupling

• propeller shaft coupling

• propeller shaft

• stern-tube bearings

• intermediate bearings where fitted

• shaft seals

• external shaft supports or brackets where fitted

• propeller

The alignment condition of one component can affect loading and behaviour elsewhere in the propulsion system.

CHOCKFAST MACHINERY CHOCKING

Large marine engines, gearboxes and other critical machinery may be installed using a pourable resin chocking system such as CHOCKFAST.

The chocking material forms a precisely fitted load-bearing interface between the machinery bedplate and its supporting foundation.

The machinery is first positioned and accurately aligned. The chocking system is then installed to maintain the machinery in the established position and transfer operating loads into the supporting structure.

CHOCKFAST should therefore not be considered simply a filler beneath an engine.

Project Manager Control

Before chocking begins, the PM should confirm where applicable:

• approved chocking product and specification

• suitability for the machinery installation

• machinery foundation condition

• final machinery position

• completed alignment measurements

• chock dimensions and arrangement

• holding-down bolt arrangement

• surface preparation

• installation procedure

• environmental conditions

• competent or manufacturer-approved installer where required

• Class attendance or approval where applicable

• curing requirements

• final bolt tightening procedure

• post-chocking alignment verification

Typical Chocking Sequence

The detailed procedure should follow the approved manufacturer's instructions, but the project sequence generally includes:

• inspect and prepare the machinery foundation

• position the machinery

• establish preliminary alignment

• carry out final alignment measurements

• confirm machinery height and position

• prepare the chock area and temporary dams

• prepare the approved chocking compound

• pour the chocks

• allow the material to cure under the specified conditions

• complete the required holding-down bolt procedure

• recheck alignment

• record the completed installation

PROPULSION TRAIN, SHAFT LINE & RUNNING GEAR

The propulsion train should be considered as one connected mechanical system extending from the main engine and gearbox through the coupling, shaft line, stern tube, bearings, external shaft supports and propeller.

A vibration, alignment or overheating problem may originate at any point within this chain.

The Project Manager should therefore avoid treating the engine, gearbox, shaft and propeller as completely separate work packages when investigating propulsion performance.

PIANO-WIRE SHAFT-LINE ALIGNMENT

Piano-wire alignment remains a useful practical method for establishing or checking the geometric centreline of a conventional propeller shaft installation.

With the propeller and shafting removed as required, a tensioned reference wire can be established through the propulsion line to provide a physical datum between the aft shaft-line reference and the gearbox or machinery position.

This can be particularly valuable when checking the position of external shaft supports such as P-brackets or A-brackets.

P-Bracket / A-Bracket Position

The alignment reference can be used to determine whether the bearing carried by the bracket is correctly positioned relative to the intended shaft centreline.

The specialist can therefore assess:

• vertical bracket position

• transverse position

• bearing centreline

• relationship with the stern tube

• relationship with the gearbox output position

• overall shaft-line geometry

This is particularly useful during structural repair, bracket replacement or investigation of an existing alignment problem.

SHAFTS, COUPLINGS & INTERFERENCE FITS

Propeller shafts and their associated couplings or hubs may incorporate accurately machined taper, keyed, keyless or interference-fit connections.

Depending on the particular propulsion system and manufacturer's procedure, assembly or removal may involve:

• mechanical pressing

• hydraulic fitting or removal

• controlled heating of the mating component where specified

• controlled shrink or interference fitting

• specialist hydraulic nuts or tooling

The Project Manager should not assume that a component can simply be heated or pressed because this technique has been used on another vessel.

The correct assembly method, interference, pull-up distance, pressure, temperature limits and final position should follow the applicable manufacturer's or propulsion specialist's procedure.

Propeller Shaft Inspection

When a shaft is removed, the opportunity should be used to inspect and measure it before reinstallation.

Inspection may include:

• shaft straightness

• run-out

• bearing journals

• seal-running surfaces

• taper condition

• key and keyway condition where fitted

• coupling surfaces

• corrosion

• fretting

• erosion

• cracking where suspected

• dimensional measurements

The results should be documented before the shaft is returned to service.

PROPELLER SHAFT INSPECTION, STRAIGHTNESS & REPAIR

When the propeller shaft is removed, its condition should be established before a decision is made to reinstall, repair or replace it.

The inspection should distinguish between dimensional measurement and Non-Destructive Testing.

Shaft Straightness & Run-Out

Shaft straightness is established by dimensional measurement rather than by NDT.

The propulsion specialist should measure the shaft to identify:

• total indicated run-out

• location of any bend

• magnitude of the deformation

• journal condition

• taper condition

• coupling surfaces

• dimensional compliance with the required tolerances

Non-Destructive Testing

NDT may then be required to identify cracking or other material discontinuities that cannot be established from straightness measurement alone.

The extent and method of NDT should be established by the shaft specialist, Classification Society or applicable repair procedure.

Repair Decision

Where the shaft is outside the permitted straightness tolerance, the specialist should produce a technical report identifying:

• measured deformation

• NDT findings

• shaft material

• proposed repair method

• applicable dimensional tolerance after repair

• Class requirements where applicable

• repair duration

• cost

• replacement alternative where relevant

The Project Manager should review the proposal and present the technical, commercial and programme implications to the Captain or Owner's Representative before authorising the repair.

Cold Straightening

Specialist workshops may use controlled hydraulic cold-straightening procedures to recover the geometry of a bent propeller shaft.

The method should be carried out under an approved specialist procedure appropriate to the shaft material and Classification requirements.

Following straightening, the shaft should be re-measured and the required inspections completed before it is released for installation.

CUTLESS BEARINGS — INSPECTION, CLEARANCE & INSTALLATION

Water-lubricated shaft bearings are precision components and their installation should be controlled against the bearing manufacturer's specified dimensions and fitting method.

Before installation, the specialist should establish:

• shaft or liner outside diameter

• bearing housing inside diameter

• housing roundness

• bearing outside diameter

• required interference fit

• required running clearance

• bearing alignment

• approved installation method

Press Fit & Freeze Fit

Depending on the bearing construction, installation may use a controlled press fit, freeze fit or another manufacturer-approved method.

The permitted cooling temperature varies significantly between bearing materials and designs.

The Project Manager should therefore ensure that the exact manufacturer's fitting procedure is available before the bearing is cooled or pressed into the stern tube, P-bracket or A-bracket housing.

A cooling method suitable for one composite bearing may damage the elastomer-to-shell bond of a different Cutless bearing.

Long-Term Static Lay-Up

A shaft bearing should not automatically be assumed serviceable simply because it has accumulated few operating hours.

Where a yacht has remained stationary for a prolonged period, the continuous static weight of the shaft may place a concentrated load on part of an elastomeric bearing.

The specialist should therefore inspect for:

• compression set

• local deformation

• ovality

• ageing or hardening

• surface deterioration

• damaged water grooves

• shaft or liner corrosion

• correct running clearance

Bearing retention or replacement should be based on measured condition and the manufacturer's acceptance limits rather than operating hours alone.

Specialist Measurement & Tolerance Report

Before the propulsion line is finally assembled, the Project Manager should obtain a dimensional and alignment report from the propulsion specialist.

Depending on the installation, this may include:

• propeller-shaft run-out

• shaft-journal dimensions

• stern-tube bearing clearances

• P-bracket or A-bracket bearing clearances

• bearing interference dimensions

• propeller taper and hub fit

• coupling dimensions

• stern-tube centreline

• shaft-line alignment

• gearbox output alignment

• engine position

• final propulsion-line acceptance measurements

STERN-TUBE SEALS & WATER-LUBRICATED SYSTEMS

Removal of the propeller shaft provides an important opportunity to inspect stern-tube seals, bearings and associated components that may otherwise be difficult to access.

Depending on the propulsion arrangement, the installation may incorporate water-lubricated bearings, lip seals, face seals or other approved stern-tube sealing systems.

Inspection

The PM should ensure inspection of:

• seal condition

• seal-running surfaces

• wear or grooving

• bearing condition

• bearing clearance

• lubrication or seawater supply

• hoses and pipework

• clamps and fittings

• evidence of leakage

• contamination

• corrosion

Replacement

Where seals are renewed, the correct seal type, orientation, installation method and shaft-surface condition should be verified before assembly.

The fact that the shaft has already been removed can make seal renewal commercially sensible, but replacement should still be based on condition, service requirements and the agreed scope.

PROPELLER & HUB INSPECTION

Propeller inspection should go beyond a simple visual check of the blades.

The propeller, hub and associated fittings form part of the complete propulsion system and should be inspected for structural condition, dimensional accuracy and evidence of previous damage or repair.

Before inspection, the propeller should be sufficiently cleaned so that damage, cracking, erosion and previous repairs can be properly assessed.

Visual Inspection

The specialist should inspect where applicable:

• blade leading edges

• blade trailing edges

• blade tips

• blade roots

• hub-to-blade transitions

• propeller hub

• taper bore

• key and keyway where fitted

• locking arrangement

• evidence of impact damage

• erosion

• cavitation damage

• corrosion

• previous repairs

• surface cracking

Any significant damage should be photographed and recorded before grinding, polishing or repair begins.

PROPELLER NDT — LIQUID PENETRANT TESTING

Surface-breaking cracks in a propeller or hub may not always be visible during normal visual inspection.

For suitable non-ferrous propeller materials, Liquid Penetrant Testing may be used to identify surface-breaking discontinuities.

Particular attention may be required around:

• blade roots

• hub-to-blade transitions

• damaged blade areas

• impact locations

• previous repair areas

• leading and trailing edges

• high-stress areas of the hub

Where a crack or unacceptable indication is identified, the propeller should remain under technical review until an approved repair or replacement decision has been made.

The Project Manager should ensure that the NDT report identifies the propeller, inspection method, inspected areas, findings and final acceptance status.

PROPELLER GEOMETRY

A propeller can appear visually satisfactory while still being geometrically incorrect.

Damage, previous repairs or blade deformation can alter the relationship between individual blades and affect propulsion performance.

Depending on the propeller type and scope of work, the specialist may verify:

• propeller diameter

• blade pitch

• pitch consistency between blades

• blade tracking

• rake

• skew

• blade profile

• blade-tip position

• surface condition

Measurements should be recorded before and after significant propeller repair where required.

PROPELLER BALANCING

After significant repair, or where imbalance is suspected, the propeller may require specialist balancing.

Depending on the propeller design and specialist procedure, this may include static and/or dynamic balancing of the propeller or rotating assembly.

Correct balancing helps reduce cyclic loading and vibration transmitted through the shaft line, bearings, gearbox and vessel structure.

Efficient propulsion also depends on correct blade geometry, pitch, surface condition and freedom from significant cavitation-related damage.

A correctly repaired, geometrically accurate and balanced propeller can therefore contribute to smoother propulsion operation, reduced vibration and efficient transmission of engine power into useful thrust.

FLEXIBLE COUPLING & THRUST-BEARING INSPECTION

Flexible coupling systems such as CENTAFLEX should be inspected as part of the propulsion train rather than considered maintenance-free components.

Depending on the particular installation, inspection may include:

• flexible elements

• fasteners

• coupling alignment

• signs of deterioration

• abnormal movement

• evidence of overheating

• lubricant condition where applicable

• thrust-bearing condition where fitted

• thrust-bearing temperature during commissioning

The exact inspection and acceptance criteria should follow the coupling and propulsion-system manufacturer's requirements.

PROPULSION SEA-TRIAL VERIFICATION

Final propulsion acceptance should include operating verification with the yacht afloat and the machinery working under representative conditions.

The sea trial should be planned so that observations can be compared at defined operating conditions rather than relying only on a general impression that the yacht feels smooth.

Checks May Include:

• stern-tube seal leakage

• seawater leakage

• gearbox oil leakage

• coupling condition

• shaft-seal temperature

• stern-tube bearing temperature where measurable

• intermediate bearing temperature

• thrust-bearing temperature where fitted

• gearbox temperature

• machinery-mount behaviour

• abnormal noise

• vibration

• shaft behaviour

• propulsion performance

• engine loading

• gearbox loading

Progressive Load Testing

Where appropriate, propulsion machinery should be observed progressively through different operating conditions rather than immediately being taken to maximum load.

Readings and observations can be taken at agreed RPM or load stages and compared between port and starboard propulsion systems where applicable.

Any abnormal increase in vibration, temperature or leakage should be investigated rather than simply completing the remaining sea-trial programme.

REINSTALLATION CONTROL

Reinstallation should reverse the removal process in a controlled and documented manner.

Before final connection, the PM should confirm where applicable:

• correct machinery unit

• serial number

• completed overhaul report

• foundation accepted

• correct mounts or chocking installed

• machinery positioned correctly

• alignment completed

• fasteners tightened to the required specification

• coupling installed and inspected

• piping correctly reinstated

• hoses supported and free from interference

• electrical connections reinstated

• control and alarm connections reinstated

• exhaust connections complete

• guards and protective covers installed

• foreign materials and temporary protections removed

PRE-START CHECKS

Before any overhauled or reinstalled machinery is started, the Project Manager should ensure that the specialist and Chief Engineer have completed the required pre-start checks.

The objective is to confirm that the machinery is mechanically complete, correctly connected and ready to operate without introducing avoidable damage during the first start.

Checks may include:

• lubricating-oil level and correct oil specification

• cooling-water level

• fuel supply available

• seawater cooling available

• valves in the correct operating position

• filters installed

• strainers clean

• piping connections complete

• hoses properly supported

• electrical connections complete

• batteries or starting system available

• control systems powered

• emergency stops tested or verified

• alarm system available

• guards installed where required

• tools and temporary materials removed

• bilges clear

• coupling and shaft area clear

• alignment work completed

• machinery mounts or chocking accepted

Priming & Pre-Lubrication

Where required by the machinery manufacturer or overhaul procedure, lubricating-oil systems should be primed before the first start so that bearings and internal components are not initially operated without adequate lubrication.

Manual Rotation

Where appropriate and permitted by the manufacturer's procedure, machinery may be turned through manually or using the approved turning arrangement before starting.

This can help confirm that the machinery rotates freely and that no mechanical obstruction remains following overhaul.

FIRST START

The first start after major overhaul or reinstallation should be treated as a controlled commissioning event.

The responsible machinery specialist and Chief Engineer should be present where appropriate, with the Project Manager coordinating the operation and recording the results.

Immediately After Start

The team should check:

• lubricating-oil pressure

• cooling-water circulation

• fuel leakage

• oil leakage

• seawater leakage

• exhaust leakage

• abnormal noise

• abnormal vibration

• charging voltage where applicable

• alarm indications

• engine or generator speed

If an abnormal condition develops, the machinery should not simply be allowed to continue running in the hope that it will settle.

The cause should be investigated before commissioning continues.

WARM-UP & OPERATING READINGS

Once the machinery has started satisfactorily, it should normally be allowed to reach operating temperature progressively while pressures, temperatures and behaviour are monitored.

Depending on the equipment, readings may include:

• lubricating-oil pressure

• lubricating-oil temperature

• coolant temperature

• exhaust temperature

• turbocharger behaviour

• fuel pressure

• gearbox pressure

• gearbox temperature

• bearing temperatures

• shaft-seal temperature

• thrust-bearing temperature where fitted

• vibration readings

• engine speed

• electrical load where applicable

The commissioning results should be compared with the manufacturer's or specialist's acceptance criteria rather than judged only by whether the machinery continues to run.

GENERATOR COMMISSIONING & LOAD TESTING

Following generator overhaul or major electrical work, satisfactory operation at no load does not demonstrate satisfactory performance under service conditions.

The generator should therefore be tested progressively under load in accordance with the manufacturer's and electrical specialist's requirements.

Checks May Include:

• stable engine speed

• generator voltage

• frequency

• phase balance

• current

• cooling-system performance

• lubricating-oil pressure

• exhaust temperature

• winding or bearing temperature where monitored

• vibration

• alarm operation

• shutdown functions

Load-Bank Testing

Where required, an external load bank may be connected to apply controlled electrical load to the generator.

This allows the machinery to be tested progressively at defined loads without relying entirely on the yacht's normal electrical consumers.

The test programme should establish the required load stages and duration.

Results should be recorded at each stage so that temperatures, pressures, voltage, frequency and overall stability can be reviewed.

HARBOUR COMMISSIONING

Before proceeding to sea trial, as many systems as practicable should be tested alongside.

For propulsion machinery this may include:

• engine operation at idle

• forward and reverse gear engagement

• gearbox response

• shaft rotation

• stern-tube seal leakage

• seawater cooling

• exhaust system

• steering interaction where relevant

• control-station operation

• alarms

• emergency stops

The harbour test should identify obvious defects before the yacht leaves the berth.

PROPULSION SEA-TRIAL VERIFICATION

The sea trial provides the opportunity to verify propulsion performance under actual operating conditions.

The trial should be planned with defined operating stages and recorded measurements rather than relying only on the impression that the yacht feels smooth.

Progressive RPM / Load Testing

Where appropriate, the propulsion system should be tested progressively through agreed RPM or load stages.

At each stage, the team should allow sufficient time for temperatures and machinery conditions to stabilise before progressing further.

Measurements may include:

• engine RPM

• engine load

• lubricating-oil pressure

• coolant temperature

• exhaust temperatures

• gearbox pressure

• gearbox temperature

• shaft-seal temperature

• stern-tube bearing temperature where measurable

• intermediate bearing temperature

• thrust-bearing temperature where fitted

• vibration

• noise

• stern-tube leakage

• seawater leakage

• coupling behaviour

Vibration Testing

Where significant propulsion work has been carried out, vibration should be assessed under representative operating conditions.

If formal vibration measurements are required, readings should be taken by a competent specialist at defined locations and operating speeds.

Possible measurement points may include:

• engine

• gearbox

• flexible coupling area

• thrust bearing

• intermediate shaft bearings

• stern-tube area

• structural locations where vibration is reported

A vibration peak appearing only within a certain RPM range may provide important diagnostic information and should be recorded rather than dismissed because the yacht feels satisfactory at another speed.

Leak & Temperature Monitoring

The propulsion system should be inspected during and immediately after the trial for developing leaks or abnormal temperatures.

Particular attention should be given to:

• stern-tube seals

• shaft seals

• gearbox seals

• cooling-water connections

• lubricating-oil connections

• hydraulic connections

• flexible coupling area

• thrust bearing where fitted

• shaft bearings

A component that remains acceptable at idle may behave very differently after sustained propulsion load.

POST-SEA-TRIAL INSPECTION

Completion of the sea trial should be followed by an inspection while the machinery condition is still representative of operation.

The inspection should consider:

• oil leakage

• fuel leakage

• seawater leakage

• coolant leakage

• shaft-seal condition

• bearing temperatures

• coupling condition

• mounts and chocking

• abnormal movement

• fastener security where required

• alarm history

• unusual smells or signs of overheating

Any defect identified during the trial should be entered into the project defect or punch list and closed through corrective action and, where necessary, repeat testing.