There are many applications for laser measurement at a shipyard, such as when building new ships, repairing damaged ones and for regular maintenance.
Alignment between propeller shaft
and main machine/gearbox
Alignment of the propeller shaft and the main machine or gearbox is carried out with shaft alignment equipment, with measuring units mounted on either side of the coupling. The measurement programs can also measure with just small rotational angles down to 40° if it is difficult to rotate the shaft, 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 sideways to get the drive line straight.
Aligning the auxiliary machine
Aligning a diesel engine and generator or other auxiliary equipment, such as pumps, motors, etc., is performed with the same shaft alignment equipment as above. The measurement system supplies the same high-quality alignment results regardless of whether the vessel is at the quay, in the dock or in motion (where the work is sometimes affected by the vessel’s movements in the water).
Shaft alignment with measuring units mounted on either side of the coupling.
Measurement of the stern tube’s roundness.
Alignment of bearing journals
in relation to stern tube
The alignment of bearing journals in relation to the stern tube (or gearbox) is carried out using bore alignment equipment. As the measurement is performed in the centre of the bearing, the instruments are suitable for both small and large shaft 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 for each bearing journal, the measurement program calculates and then displays the position in the vertical and horizontal directions. As adjustment is performed on land or in the dock, compensation values can be entered if required in order 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 fixture with a measurement probe, see image.
of slewing ring bearings
Slewing cranes are sometimes found in ports and on vessels. In order for these to work without problems, the bearing must be flat. When measuring the flatness of s slewing ring bearing (see image), a separate laser transmitter is used, such as the Easy-Laser® D22, which sweeps across the surface. The transmitter is mounted directly on the bearing using super magnets, after which the detector is placed at selected points around the bearing and 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.
Flatness measurement of slewing ring bearings.
Here we can see the belt assembly on the ferry Marie, which travels between the mainland and Öckerö in Gothenburg’s archipelago. Two motors power one drive shaft, which in turn is connected to a 360° rotating propeller pod.
In car ferries, for example, the drive system can sometimes comprise powerful sheave/pulleys (see image). Laser-based measurement systems are ideal for this particular type of application. Of course, there may also be other systems on vessels 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.
The majority of large-scale manufacturers of diesel engines also use Easy-Laser in their production for checking the straightness (centre line) of crankshaft and camshaft bearings. 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).
Checking bearing play
It is possible to check whether the bearing play is within tolerance by installing measurement units on the shaft and on fixed components in the machinery. After this, the shaft is lifted with a pulley or jack, and the movement (the play) is recorded. Read more about this in this blog article about the tourist boat MS Tonne.
Checking the centre line of the bearing journals (straightness in two dimensions).
Straightness measurement of the machine base.
Checking and measuring when the vessel hull has been redesigned
An unusual application! However, this is actually just a variant of the normal straightness measurement, where Easy-Laser is used for rough alignment. We’re not talking about hundredths of a millimetre here...
Mauro Regali at Azzurra Tecnology has considerable experience of complicated measurements. In this case, the front and rear sections had to be positioned a little way apart in order to be able to extend the hull (see picture).
Easy-Laser possesses extensive knowledge in the fields of measurement and alignment for the shipyard industry. We have developed alignment solutions for “single bearing drive lines”, as well as customised solutions for drive lines with 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 e.g. 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 whose assignments cover a broad range. A good example of this is On Site Alignment, which uses Easy-Laser and is a specialist in vessel applications. Please feel free to visit On Site Alignment's website.