Engine & Machinery Overhaul and Riding Squads

Marine engine and machinery overhaul and riding squads

Marine engine and machinery overhaul covers planned and corrective maintenance of main engines, auxiliary engines, turbochargers, pumps, compressors, purifiers and other engine-room machinery, carried out by shore teams alongside, in dry dock or by riding squads during a voyage. Machinery work often has to fit a cargo schedule rather than a workshop schedule. Riding squads allow inspection, overhaul, measurement and repair to continue at sea or across several ports, while larger teams can execute concentrated work packages during a port stay.

vslSafety coordinates the trade mix, travel, tools, spare parts and reporting around a defined work package, drawing on engine fitters, machinists, welders and maker-authorised service engineers at or near the vessel’s port.

Regulatory requirements and standards

Overhaul intervals normally follow maker running-hour guidance, condition monitoring, the company’s planned maintenance system and class machinery survey arrangements, rather than one universal statutory interval.

• Class machinery surveys. Under IACS UR Z18, machinery special surveys are carried out on a five-year cycle and may be done as a continuous survey, where the interval between consecutive examinations of each item must not exceed five years. Surveys may also be carried out on a planned maintenance scheme basis (IACS UR Z20) or a condition monitoring and condition-based maintenance basis (IACS UR Z27). Class may credit some items examined by the chief engineer, subject to confirmatory survey.
• Machinery verification runs. UR Z18 requires a dock trial at the special survey, and significant repairs to main or auxiliary machinery or steering gear may call for a sea trial.
• ISM Code section 10. The company must maintain the ship and identify critical equipment and technical systems whose sudden failure could lead to hazardous situations.
• SOLAS II-2 fire safety. External high-pressure fuel delivery lines must be jacketed with leakage collection and an alarm (regulation 4.2.2.5.2), and surfaces above 220°C that could be impinged by a fuel leak must be properly insulated (regulation 4.2.2.6). Reinstatement after overhaul must restore these protections.
• MARPOL Annex VI and the NOx Technical Code 2008. Where engines use the engine parameter check method, all replacements and adjustments of NOx-critical components and settings, including like-for-like replacements, must be recorded in the Record Book of Engine Parameters.
• Maker service letters and bulletins from engine designers such as MAN Energy Solutions, WinGD and Wärtsilä define inspection intervals, clearances and modifications.

Typical maintenance intervals

What the service includes

• Main engine cylinder unit overhaul: piston, rings, liner calibration, cylinder cover and exhaust valve
• Crankcase inspection, bearing clearance and crankshaft deflection measurements
• Auxiliary engine top and major overhauls, including connecting rods and main bearings
• Turbocharger inspection and overhaul, often with maker-authorised engineers
• Fuel injection pump and injector overhaul and testing
• Pump, compressor, purifier, heat exchanger and valve overhaul
• Engine-room pipe renewal, machining, alignment and chocking support
• Riding squads for voyage repairs, planned maintenance backlogs and pre-dry-dock preparation
• Measurement sheets, daily progress reports, spare-part reconciliation and completion reports

Machinery and makers covered

Teams commonly work on two-stroke main engines designed by MAN Energy Solutions and WinGD, four-stroke engines from Wärtsilä, MAN, Yanmar, Daihatsu, Caterpillar/MaK and Hyundai HiMSEN, turbochargers from ABB (Accelleron), MAN and Mitsubishi, purifiers from Alfa Laval and GEA, and air compressors from Sperre, Tanabe and Hamworthy. Engine-room electrical work is often combined with electrical and automation services, and shafting and propeller work with propeller and shaft services.

Common defects and PSC deficiencies

• Fuel and lubricating oil leaks, oily bilges and oil-soaked insulation, which PSC treats as a fire hazard
• Missing or damaged insulation on exhaust manifolds and hot surfaces
• Jacketed fuel pipe leak alarms inoperative or leakage collection blocked
• Emergency generator or emergency fire pump failing to start
• Overdue maintenance of critical equipment against the planned maintenance system
• Crankcase explosion relief valves, oil mist detectors or safety shutdowns not tested

Certificates and documents you receive

• Completion report with work done, measurements before and after, and photographs
• Calibration, clearance and deflection records
• Test run record and acceptance results
• Maker service report where a maker engineer attends
• Material, NDT and welding certificates for class items
• Information for updating the Record Book of Engine Parameters

Class survey reports and credits are issued by the attending class surveyor.

How to prepare the vessel and plan a riding squad

Define the work list, acceptance tests and report format before mobilisation. Confirm engine immobilisation permission from the port where main engine work is planned alongside. For riding squads, check that the total persons on board stays within the ship’s life-saving appliance capacity and certificates, and add the team to muster lists, security arrangements and the crew list. Arrange cabins, food, PPE, familiarisation and permit-to-work systems. Whether riding team members count as seafarers under MLC, 2006 is decided by the flag Administration, so confirm employment and documentation requirements early. Boiler work can be combined with boiler and economiser servicing.

Information needed for a quotation

• Vessel name, IMO number, flag, class and trading schedule
• Port or voyage leg, ETA/ETD and time available
• Equipment maker, model, serial number and running hours
• Job list, manuals, drawings, previous measurements and class recommendations
• Spare parts and special tools on board, and those to be supplied
• Who supplies consumables, machining, transport, visas and flights

vslSafety coordinates a suitable workshop or riding team at or near the vessel’s port and confirms scope, manpower and logistics before mobilisation.

Frequently asked questions

What is a riding squad?

A riding squad is a team of fitters, welders or technicians that sails with the vessel to carry out maintenance or repairs during the voyage. It lets work continue without taking the ship off hire and suits jobs such as auxiliary engine overhauls, steel and pipe renewals, tank preparation and planned maintenance backlogs. The team is embarked and disembarked at convenient ports.

How often should a main engine be overhauled?

There is no fixed statutory interval. Overhauls follow the engine designer’s recommended running hours, adjusted by condition monitoring, scavenge port inspections, measurements and service letters. Class requires each machinery item under continuous survey to be examined at least once every five years.

What is continuous machinery survey?

Under continuous survey, class examines machinery items in rotation so that each is surveyed within five years, instead of all at the special survey. Some items can be examined by the chief engineer and credited by class after confirmatory survey, depending on the society’s rules.

Do replacement engine parts affect NOx certification?

They can. For engines using the parameter check method, every replacement or adjustment of NOx-critical components, including like-for-like parts, must be recorded in the Record Book of Engine Parameters. Parts must match the identification in the engine’s Technical File, so check part numbers before fitting.

Does class need to attend an engine overhaul?

Routine overhauls are normally recorded and reviewed at the next survey, but work on crankshafts, major repairs, alterations to class items or damage repairs usually require class attendance. Confirm with the class society before the work starts to avoid repeating inspections.