Alignment of machinery on ships

Easy-Laser has alignment systems for different types of marine propulsion systems, such as propeller shafts, pods and water jets. In addition to this we can offer solutions for a variety of other applications, such as straightness and flatness.

Complete but customized solutions

Our laser measurement systems for the marine industry are used for both the construction of new ships and for maintenance work. A major advantage is the ability to combine parts from different Easy-Laser measurement systems to optimize the functionality for different types of users, instead of having to invest in several different, complete systems. For example, combining shaft alignment systems with laser transmitters for flatness measurement and drive line straightness. It is cost-effective, and an advantage for technicians who only need to learn one type of measurement system. A propeller shaft drive line may consist of different parts depending on ship design; Drive shaft, bearing support, stern tube, gearbox, motor, couplings. You usually want to align the components in a straight line (or according to a predetermined curve).   

Alignment of the propeller shaft and gearbox

Alignment of the propeller shaft and the main machine or gearbox is carried out with shaft alignment equipment, with measurement devices mounted on either side of the coupling. The measurement devices are mounted using chain brackets around the shaft or coupling, or using strong magnet bases. In some cases, one of the measurement devices can instead be placed on the flywheel of the motor. Easy-Laser's measurement programs can measure with as little as 40° rotation of the shaft. Useful if the shaft is difficult to rotate, or if pipe connections or other hull components are in the way. The results of the measurement show how to shim and adjust the motor/gearbox laterally to get the drive line straight. Adjustment to the correct position is made using Live values.

Shaft alignment onboard ship
Shaft alignment with measuring units mounted on either side of the coupling.

Alignment of bearing journals in relation to stern tube

A laser beam can be used for stern tubes and bearing journals, when the shaft is removed, along the centre line. This is what we call bore alignment. An example of a measurement system used for this is Easy-Laser E950. Because the measurement is performed in the centre of the bearing, the instruments are suitable for shafts of both small and large diameters. The measurement method is based on a laser transmitter being mounted on the axial surface at one end of the stern tube (or on the gearbox flange or in the final support bearing) and the detector unit being placed in the bearing journal. Measurement values are recorded at a distance in the bearing sleeve as shown in the drawing. The measurement program makes calculations and then shows the position in the vertical and horizontal axes as well as first and second "slope" if necessary. As adjustment is performed on land or in the dock, if required compensation values can be entered to correspond with the position of the bearings when the vessel is in the water. 

If necessary, the roundness of the bearing can also be checked. This is best performed using a bracket with a measurement probe, see image.  

Easy-Laser can be used to measure bearing play: mount one measuring unit on the shaft and the other to a fixed part of the machinery. Then raise the shaft (with an aid) and read off any play. 

On water jet drive systems, it may be desirable to align to a mounting flange (i.e., a surface perpendicular to the centre line of the shaft). A laser transmitter with integrated angular prism is then needed, e.g. Easy-Laser D25. 

Measurement of stern tube roundness
Measurement of the stern tube’s roundness.

Installation and checking of motors

The motors must be mounted on a flat base, with flat parallel support surfaces for the feet. Flatness is best checked using a laser transmitter with sweep, e.g. Easy-Laser D22, and flatness software. This applies to both electric motors and diesel engines. 

A diesel engine's main and cam bearing (with relevant shaft removed) positions are checked for straightness. This is done with a Linebore-system. One indirect measurement is checking the straightness of the motor base, which can indicate that the machine has been incorrectly set up/installed (see image). Read more about checking and aligning diesel engines here.

Checking the centre line of the bearing journals (straightness in two dimensions).

Other machinery aboard a ship that needs aligning

Rotating machinery in support systems, such as diesel engines/generators, bilge pumps and crude oil pumps etc. is aligned with the same shaft alignment equipment as for drive lines. The measurement system supplies the same high quality alignment results regardless of whether the vessel is at the quay, in the dock or at sea (where work is sometimes affected by the ship’s movements in the water). With Easy-Laser, you can also check flatness of the bases for rudders, pumps, cable winches, and capstans.

Flatness measurement of slewing ring bearings

Cranes for freight handling are installed on rotating bases, with slewing ring bearings. These may be on land or permanently on a ship. The bearing must be flat in order for a crane to work problem free. This can be checked with ”flange flatness” software, sweeping laser and detector. The transmitter is mounted directly on the bearing using super magnets, after which the detector is placed at selected points around the bearing and the measurement values are recorded. The software automatically calculates the best-fit results for optimum adjustment. You can also move the zero points manually to find the values that entail the least tooling work.

Sometimes, the crane may run on rails that must be parallel and level. With Easy-Laser you can make sure that is the case.

Flatness measurement of slewing ring bearing
Flatness measurement of slewing ring bearings.

Belt-driven systems

In car ferries, for example, the drive system can sometimes comprise powerful sheave/pulleys (see image). Laser-based measurement systems such as the XT190 are ideal for this particular type of application. There may also be other systems on ships that are powered by belts and that need to be aligned in order to eliminate vibrations, increase efficiency and extend the time between belt replacements.  

Belt drive on ship
Here we can see the belt assembly on a ferry. Two motors power one drive shaft, which in turn is connected to a 360° rotating propeller pod.

Customized solutions for less common alignment problems

Easy-Laser possesses extensive knowledge in the fields of measurement and alignment for shipyards. We have developed alignment solutions for “single bearing drive lines”, as well as customized solutions for drive lines with Cutless bearings (water-lubricated rubber bearings).

Depending on which applications you need to align, we can put together a measurement system that meets your particular requirements. By combining components from, for example, a bore alignment system and a shaft alignment system in a smart manner, you can obtain an extremely cost-effective solution. This makes Easy-Laser perfect for service companies and machine installers with a broad range of assignments. A good example of this is On Site Alignment, who use Easy-Laser and are specialists in marine applications. Please read more in this  blog post.

 

Further application areas for ships and shipyards 

  • Rudder stocks can be aligned to the center line, to the correct angle.  
  • Centre line (bore alignment) for hinges for large hatch covers.  
  • Alignment of hull sections for extensions to ships. 
  • Pump systems and transporters for loading/unloading of bulk materials and liquids.