An eye on auxiliary damage

Claims for auxiliary engine damage cost an average of US$344,615 Claims for auxiliary engine damage cost an average of US$344,615

A new report from insurance company The Swedish Club, placing the blame for most auxiliary engines on poor maintenance, gives an insight into why owners might look to swap gensets for batteries.

“Imagine picking your car up from the workshop after regular maintenance. On your way home there is a loud noise from the engine and the car comes to a shrieking halt. You open the hood to see the engine has failed catastrophically, with bits and pieces from liners and pistons scattered all around.”

According to The Swedish Club, that is what happens in more than half of all auxiliary engine failures. The insurer investigated seven years of claims across nearly 3,000 ships to come up with some worrying insights. Chief among those is the finding that 55% of all incidences of auxiliary engine failure occur within 1,000 hours of overhaul – within 10% of time between overhaul (TBO) given that typical TBOs are 12,000-16,000 hours.

Auxiliary engine failures are a common cause of insurance claims. They occur, on average, on one of every 100 vessels each year, representing 7% of hull and machinery claims and 16% of machinery claims. Container vessels have a significantly higher claims frequency due to the larger number of installed engines on these vessels. In addition, these engines have considerable output, hence the repair cost is greater compared with other vessels

Although they are by no means the most expensive of machinery claims, an average cost of over US$344,000 makes them are a significant contributor to premiums. This expense is even more unpalatable given that mistakes on the part of crew are a prime cause of damage. The club records that the common factor in most cases is the ‘incorrect assembly of vital engine parts in connection with regular overhaul’. In particular, the assembly of connecting rods, bearings and pistons cause severe and costly accidents (see box).

Non-adherence to procedures, lack of training and experience are major factors. A connecting rod assembly, for example, is a critical and highly stressed joint and must be re-assembled exactly in accordance with manufacturer’s instructions with proper tools. Special hydraulic tools used for engine assembly need to be calibrated and carefully checked before use.

The club reports seeing insufficient understanding of the importance of these procedures ‘all too often’. The manager has the responsibility to ensure that crew are competent to undertake such repairs. Crew should either be trained on the specific engine types, the study explains, or an expert from the manufacturer should be engaged to attend the overhaul.


Poor lubrication oil management is in many cases the predominating factor for an auxiliary engine breakdown, the club reports.

Auxiliary engines are four-stroke engines and as such the engine oil is used for cooling of pistons crowns and lubrication of parts including cylinder liners and bearings. There is a risk that the lube oil will be contaminated with soot and combustion particles, especially if the engine has accumulated some running hours.

Proper lubrication oil management is critical for minimising the risk of engine failures. This is essential when operating the engine on heavy fuel oil (HFO). The lubrication oil must be analysed at regular intervals. Detection of water, soot particles and metal particles will serve as an early warning for engine problems. The authors caution that negative results from oil analysis must be investigated and addressed promptly.

“Whilst prevention is always better than cure, steps can be taken to mitigate the damage caused by the failure of the auxiliary engine,” the report concludes. Most modern auxiliary engine installations can be started and stopped remotely from the engine control room. But it is good practice to be present at the engine when starting, especially after longer periods of still-stand and after overhaul. If someone is present at the engine there is at least a possibility to intervene and shut down the engine manually.

Causes of damage

The Swedish Club identified four major causes of auxiliary engine damage:

Connecting rod bolts (58 cases):

  • Improper tightening of bolts;
  • Hydraulic tool/pump not calibrated;
  • Lack of crew training and adherence to procedures.

Contamination of lubrication oil (27 cases):

  • Improper lube oil management;
  • Lube oil filters degraded over time;
  • Introduction of dirt (rags) during maintenance;
  • Damage/leaking lube oil cooling water heat exchanger.

Incorrect maintenance & procedures (25 cases):

  • Incorrect adjustment of valve clearance;
  • Installed pistons in wrong directions;
  • Installed wrong type of plungers in fuel pumps;
  • Mixed up inlet and outlet valves during overhaul;
  • Not following manufacturer’s service letter regarding required modifications;
  • Not installing correct bearings following crankshaft grinding.

Overspeed (16 cases):

  • Overspeed trips not in working condition;
  • Wrong assembly after exchange of governor;
  • Wrong assembly of fuel linkage;
  • Worn out drive system for governor.

The Swedish Club machinery claims by type, 2010-2016


Claims Type

Number of claims

Cost (US$)

Average cost (US$)

Main engine








Auxiliary engine








Steering gear




Boiler, auxiliary boiler








Electrical, engine room automation




Cargo gear and equipment, cargo heating




Deck equipment, other




Stern tube













Note: *Propeller, shaft, gearbox; **Machinery and equipment for lifesaving, navigation, thruster, etc.

Source: The Swedish Club, 'Auxiliary Engine Damage', 2018

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