Laser alignment at sea: modular measurement systems for modern shipyards

Alignment of the propeller shaft and the main machine or gearbox is performed with shaft alignment equipment. Measuring units are mounted on each side of the coupling, typically using chain brackets around the shaft or coupling, or strong magnetic bases. In some installations, one measuring unit can instead be mounted directly on the motor flywheel.

In marine environments, access is often limited by pipework, hull structures, or the sheer size of the shaft. Easy-Laser measurement programs therefore allow alignment with as little as 40 degrees of shaft rotation. The results show how to shim and adjust the motor or gearbox laterally, while live values guide the final positioning during adjustment.

Bore alignment: measuring the stern tube and bearings
When the shaft is removed, laser measurement can also be used to check the stern tube and bearing journals along the centre line—a procedure commonly referred to as bore alignment. The method is suitable for both small and large shaft diameters.

The process is based on mounting a laser transmitter on the axial surface at one end of the stern tube, or on the gearbox flange or final support bearing. A detector unit is then positioned in the bearing journal. The measurement program records values and calculates the position in both vertical and horizontal directions, including slope values where required.

Because many adjustments are carried out on land or in dry dock, compensation values can be applied to reflect how the bearing position will change when the vessel is afloat. This is an important consideration in marine alignment, where the operating condition of the hull can differ from the condition during installation or repair.

Additional checks may include bearing roundness, typically carried out with a bracket and measurement probe, as well as bearing play. In the latter case, one measuring unit is mounted on the shaft and another on a fixed machine part. The shaft is then lifted using suitable equipment, and any play can be read directly from the system.

Installation checks for motors and engines
Motors and engines depend on a flat and stable base. If the support surfaces are uneven or not parallel, stresses can be introduced into the installation, affecting alignment and long-term performance. Flatness is best checked using a sweeping laser transmitter, such as the Easy-Laser XT22, together with flatness software. The same principle applies to electric motors and diesel engines.

For diesel engines, the straightness of main and cam bearings is checked with the relevant shafts removed, using a line bore measurement system. An indirect but valuable check is to measure the straightness of the engine base, which can reveal incorrect setup or installation conditions before they develop into operational problems.

Belt drives, cranes, and auxiliary equipment
Marine alignment is not limited to propeller shafts and engines. On vessels such as car ferries, the drive system may include powerful sheaves or pulleys. Laser-based measurement systems are well suited to these applications, where accurate pulley alignment helps reduce vibration, improve efficiency, and extend belt service life.

Custom configurations for specialist tasks
Shipyards and marine service companies frequently encounter less common alignment challenges, including single-bearing drivelines and installations with cutless bearings, or water-lubricated rubber bearings. In such cases, a modular system can be configured to match the task rather than forcing the task to fit a fixed equipment package.

By combining components from bore alignment and shaft alignment systems, users can create a cost-effective solution for a wide range of marine applications. This flexibility is particularly valuable for service providers and installers who move between vessels, machinery types, and measurement conditions.

Flatness measurement for slewing ring bearings
Freight-handling cranes, whether installed on land or permanently on vessels, are mounted on rotating bases with slewing ring bearings. For safe and reliable crane operation, the bearing surface must be flat. Even small deviations can influence load distribution and mechanical performance.

Flatness is checked using flange flatness software together with a sweeping laser transmitter and detector. The transmitter is mounted directly on the bearing using strong magnets, while the detector is placed at selected positions around the bearing to record measurement values. The software calculates best-fit results for optimal adjustment, and zero points can be moved manually to reduce the amount of tooling work required.

In some installations, cranes run on rails that must be both parallel and level. The same laser measurement platform can be used to verify and adjust these conditions, expanding its role from driveline alignment to broader structural and machinery checks.

One platform for many onboard applications
The same measurement principles apply to many other rotating machines on board, including diesel engines, generators, bilge pumps, and crude oil pumps. Consistent shaft alignment helps maintain reliability across the vessel’s support systems, while base flatness checks can be applied to components such as rudders, pumps, cable winches, and capstans.

For shipyards and maintenance teams, the value lies not only in measurement accuracy but also in repeatability and usability. Working from a common platform makes it easier to standardize procedures, train technicians, and document results across different projects and vessel types.

As vessels become more complex and uptime expectations increase, alignment practices are moving from corrective maintenance toward preventive quality control. Laser measurement provides the data needed to identify deviations early, support accurate installation, and verify that adjustments have been made correctly.