Himsen Auxiliary Engine Vibration – Multichannel Ship Vibration Case Study

When vibrations create operational risk – not clear answers

Recurring vibration issues on board a vessel are not only a technical concern but also a serious operational risk. They can lead to repeated service interventions, limited equipment availability and costly troubleshooting efforts without a clear understanding of the root cause.

This case study presents how multichannel vibration measurements were used to investigate persistent failures affecting Himsen 5H21/32 auxiliary engines and their generators, ultimately providing the data required to stabilise the operation of the machinery system.

Operational bacground

The case concerns a modern LNG carrier built in 2017–2018. Shortly after entering service, the vessel began experiencing recurring technical problems with its Himsen 5H21/32 auxiliary engines driving the generators.
The failures manifested as the presence of white metal particles in the lubricating oil, indicating progressive bearing damage and abnormal loading conditions within the engines.
Despite several repair attempts carried out over multiple years, the problem continued to reappear.

Situation before the vibration investigation

Following the most recent overhaul and installation of new components, one of the generators driven by a Himsen 5H21/32 auxiliary engine operated for only 12–16 hours under load before white metal particles again appeared in the lubricating oil.

At the same time:

• another generator also showed signs of bearing wear

• its operation had to be limited to 30–40% load to avoid severe damage

Despite ongoing involvement from the engine manufacturer and several proposed technical modifications, no definitive root cause had been identified.
Because the failures continued despite major repairs and structural modifications, the case evolved into a technical and insurance dispute.
The shipowner required an independent technical assessment to determine whether the failures were related to:

• engine design or manufacturing issues

• structural characteristics of the vessel

• vibration behaviour of the propulsion and machinery system

In this context, a multichannel vibration measurement campaign was commissioned to obtain objective data and better understand the mechanisms behind the recurring failures.

History of repair actions

Before external vibration specialists were involved, the vessel underwent several major repair actions on the Himsen 5H21/32 auxiliary engines, including:

• multiple crankshaft replacements performed over several years

• installation of a reinforced back plate and upgraded vibration dampers following recommendations from the engine manufacturer

• structural reinforcement of the hull, performed by a specialised engineering company

The total cost of spare parts, repairs and technical services related to these actions exceeded USD 500,000.
Despite these extensive interventions, the implemented solutions did not resolve the issue.

Measurement scope and methodology

Measurements were performed during sea trials under varying engine speeds and load conditions, allowing the behaviour of the propulsion and machinery system to be observed in real operating conditions.

A total of 32 vibration measurement channels were recorded simultaneously.

The measurement campaign covered:

• Himsen 5H21/32 auxiliary engines and their generators

• the Hyundai-MAN B&W 6G70ME main engine

• main engine foundation and structural bracing

• shaft line components

• selected areas of the ship’s structure

Vibration sensors were installed in defined directions to capture machine and structural response in three axes:

• vertical (V)

• transverse (H)

• longitudinal (A)

The measurements were evaluated based on the experience of the diagnostic team, taking into account generally accepted vibration assessment practices, applicable international standards, shipowner requirements and classification society guidelines.
Simultaneous multichannel acquisition allowed the correlation of vibration behaviour between machines and the vessel structure, eliminating uncertainty caused by changing operating conditions.

Vibration behaviour of Himsen 5H21/32 auxiliary engines

The recorded data showed that vibration levels changed with the operating conditions of the propulsion system and that similar frequency characteristics appeared in different areas of the vessel.
Importantly, not every location with elevated vibration levels represented the actual source of the problem.
The behaviour of the Himsen 5H21/32 auxiliary engines and the surrounding structure suggested that the observed vibrations were not random, but were closely related to the operating conditions of the propulsion and power generation system.
Spectral analysis did not indicate typical bearing defect frequencies during the early stages of operation, suggesting that the failures were linked to system-level dynamic behaviour rather than a single local defect.

Main engine and structural response

Measurements confirmed that vibration originating from the main engine (Hyundai-MAN B&W 6G70ME) did not influence the operation of the Himsen auxiliary generator sets and was therefore excluded as a contributing factor.

Shaft line and bearing assessment

Measurements performed on shaft line components showed stable vibration behaviour across the operating range, without abnormal harmonic growth.
This stability provided an important reference point when interpreting the behaviour of the auxiliary engines and surrounding machinery systems.

Conclusions and operational outcome

The multichannel vibration analysis provided a system-level understanding of the vessel’s vibration behaviour and allowed informed technical decisions to be made.
Key conclusions included:

• vibration phenomena must be analysed at the system level, not only at individual machines

• sea trial data proved essential for identifying the mechanisms behind the failures

• multichannel vibration measurements significantly reduced diagnostic uncertainty

• the collected data allowed targeted technical actions to be implemented

Following the implementation of actions based on the measurement results:

• vibration levels stabilised

• previously recurring failures stopped appearing

The problem was permanently resolved, without the need for further costly and unjustified component replacements.

Are you experiencing similar vibration problems on Himsen auxiliary engines?

Recurring generator bearing failures, white metal in lubricating oil or unexplained vibration levels may indicate system-level vibration problems rather than a single component defect.
Multichannel vibration measurements allow identification of the real source of such issues and support data-driven technical decisions.
If you are facing similar challenges on board your vessel, the IM team can assist in planning and executing a dedicated vibration investigation.

Before making a costly decision, it is worth measuring and understanding the behaviour of the entire system.