3D laser scanning and modeling: an efficient solution for BWT retrofits
Lack of precision while measuring ballast water treatment system installation space can result in the equipment not fitting exactly as planned, leading to unforeseen costs.
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To avoid unexpected complications during the installation process, Goltens Green Technologies recommends laser scanning of the installation space, followed by 3D modeling and prefabrication. Laser scanning provides an accurate and efficient solution for fitting a ballast water treatment (BWT) system onboard. It also eliminates most of the risks associated with manual measurement and fabrication onboard without prefabrication.
Often, particularly for older vessels, existing drawings are inaccurate, and having a 3D laser scan ensures that the subsequent engineering design is based on the actual configuration of the ship.
Depending on the ship size, Goltens Green Technologies experts often need less than 10 hours onboard a vessel to scan the entire area where the BWT system will be installed. The scan does not disturb the vessel’s operation and it is not even necessary for the crew to leave the engine room during the scan.
The laser scanner has an accuracy of 2 millimeters, allowing for precise measurements and the creation of highly detailed three-dimensional images of the engine room.
As the scanner rotates, the laser beam hits the surface of an object, generating a measurement in both distance and angle. One complete turn of the scanner creates a point cloud of 10 million dots containing information that is used to create a 3D image. The scanner is moved around the engine room to ensure all areas are captured by the laser beam. Afterwards, all the images taken from different points are pieced together to create a complete 3D image of the space.
Processing the scan results
The point cloud generated by the scan is put directly into a 3D CAD program to start modeling the BWT system into the existing space. At this point, it becomes possible to see exactly how the BWT system would fit and whether there would be sufficient space left to walk around it and service it. It is also possible to compare different options in case the shipowner has shortlisted more than one BWT system and is not sure which one would fit best. Shortlisted systems can be modeled to show which would be the optimal solution in terms of fit.
One of the advantages at this stage is that both shipowner and chief engineer can clearly see how the system will fit before any further actions are taken. They can voice their thoughts and suggestions if they want anything to be rearranged, and Goltens Green Technologies experts will look into the options for implementing their requests.
Due to the high accuracy of the laser scanner, it is possible to make production drawings directly from the scan results. The high accuracy of the process makes even the use of fitting pipes unnecessary in most cases.
It is common to use steel for BWT system installations, which is normally left ungalvanized to allow for adjustments. When all the adjustments are done, the steel can be welded and galvanized. This means, however, that about five extra days need to be calculated into the schedule, allowing time for the steel to return from a galvanizing plant. Laser scanning and accurate prefabrication allows for these pipes to be galvanized prior to installation onboard and can save this valuable time that would be otherwise needed onboard.
Goltens Green Technologies experts also prepare drawings for the foundations. Furthermore, a laser scan can provide shipowners with a comprehensive overview of all the parts needed for an installation, which can save time and effort. This is especially important when installing a system at sea where the delays and logostics with putting the piping ashore for galvanizing presents an additional challenge.
It is important to realize that the production company should have the same accuracy as the laser scan used to make an onboard survey. Otherwise, the advantage of having such a highly accurate scan is lost. For instance, if a shipyard can’t make the pieces fit, they have to remake the pipes. This is a very costly exercise as it requires the shipyard to install, uninstall, refabricate and reinstall all of the piping. This costs the yard and the owner precious time and money.
Goltens Green Technologies specialists also prepare a detailed material list. This way, the shipowner gets a complete production package that they can use at any shipyard of their choice. This also helps keep track of the costs by projecting a realistic price estimate based on the amount of materials needed. This makes it easy to compare estimates from different shipyards and to choose the optimal solution.