By Keith Norbury

Three-dimensional modeling of ship design has great potential in ship repair. However, it is a potential that has barely been exploited, says Dr. Christian Cabos of the German shipbuilding classification society Germanischer Lloyd. “The major benefit is for the shipowner to be able to identify the scope of the required repair early on, to put him in a favourable position to negotiate the price of the repair with different yards,” said Dr. Cabos, Vice-President of Information Management and Tools at GL Classification, the company’s research and rule development department. “Typically, if you know only approximately what the damage to your ship consists of, you are not able to specify in a detailed way to the yard what the scope of the repairs should be,” Dr. Cabos said. “They will always find some other things which have to be fixed once you are in the yard. And that will raise the cost of the repair.” However, he estimates that only a small percentage of shipowners own and use 3D modeling software.

Problem with yards and their intellectual property

One problem facing adoption of 3D modeling in ship repair is the general reluctance of shipyards to make detailed models available to shipowners, “because of the intellectual property issues,” said Dr. Cabos. The fear is that the shipowner might take that design to another yard, and build an identical ship.

“So if you want to have a 3D model of your vessel, what you need to do is to use the drawings you get with the vessel to build a 3D model from them,” Dr. Cabos said. “And of course, you will need to have permission from the yard to do that.” In that way, a shipowner might negotiate with a shipyard to use the 3D renderings for ship operation and repair. But using 3D models in that way is such a new field that such practices aren’t yet common. However, they are happening in the case of floating offshore platforms, which have very high requirements for structural integrity, Dr. Cabos said. “There the interest is so high in having detailed models of the vessels that the owner will negotiate with the yards at the beginning when they are ordering the vessel that they not only get the vessel but that also a model of the vessel,” Dr. Cabos said. In fact, GL is about to initiate a project to bring owners and yards together to “negotiate what would be the conditions under which we can make this a standard,” he said.

U.S. Coast Guard and navy require delivery of 3D models

Darren Larkins, CEO of Victoria, B.C.-based ShipConstructor Software Inc. said the intellectual property considerations have been a huge challenge, but are becoming less so.

“I think there has been a transition, and continuing to be one to require in the contracts delivery of a general model of the ship, as well as the actual native software,” Mr. Larkins said. “Most contracts governing activities involving ShipConstructor say you must deliver the ShipConstructor model.” For example, the U.S. Coast Guard recently made it a requirement that designs of its vessels must be delivered in ShipConstructor. And the U.S. Navy requires that its ship designs be delivered in whatever computer-assisted design (CAD) model was used, although without specifying a particular product.

Mr. Larkins did, however, acknowledge that such requirements can place shipyards and shipowners in a difficult position because both can feel they have a claim to the ownership of the design. “And it is a huge problem,” he said. “It’s still not even clear. Even with the Navy where they say you must deliver, who owns it is very much in question.”

He cited a recent U.S. Navy project in which Gibbs & Cox was the designer, Lockheed Martin was the prime contractor, and the shipbuilder was Marinette Marine, with a second vessel to be built by another shipbuilder. “So who owns the model?” Mr. Larkins said. “Gibbs & Cox thinks it’s an interesting design and wants to sell it to the Israelis. And Marinette says, “Well, we actually did the engineering work and we want to build it for somebody else.’ And the U.S. Navy says, “You need to deliver it. It’s ours,’” Mr. Larkins said.

Dr. Cabos said that Sener, one of the major developers of 3D ship design software, is providing interfaces to use a standard format to export only ship hull information necessary for ship operations. “The concerns regarding intellectual property rights are smaller when they’re using that kind of interface,” Dr. Cabos said. And software giant Adobe now has technology to “safeguard intellectual property rights” with 3D PDF files, he said.

Hullmanager enables damage assessments at sea

GL’s Poseidon System, which is designed for rules analysis to ensure that standards are met during construction, can also be used in ship repair, Dr. Cabos said. “If it is a conversion, for example, or a large scale repair, you would do a re-analysis concerning the actual state of the vessel, the corroded state of the vessel, and use Poseidon for that purpose.” GL Hullmanager, however, has more obvious applications for ship repair “because the software is being used to record inspection findings concerning the ship construction. So if you find any damage, any dents or bucklings or cracks, then you would record that in that software and use the original display of the software to communicate with a ship repair yard,” Dr. Cabos said. Because GL Hullmanager has a neutral interface standard, called open Higher Condition Model, or open HCM, it can use 3D models regardless of the system they are built in, Dr. Cabos said. Hullmanager is at present offered free for vessels built with GL’s 3D software.

Hullmanager enables a vessel owner to determine upon inspection precisely what needs to be repaired, and to communicate that “in concise fashion” to shipyards in order to obtain quotes on competing bids on the repair work. Germanisher Lloyd also provides a 24-hour for-fee service that in the event of an emergency, such a collision, grounding or the appearance of a large crack, a vessel operator can call from onboard for an analysis of the damage. “Then we can give them advice on how to operate so that the risk for total loss is lower,” Dr. Cabos said.

Where models don’t exist, they can be created

Ideally, the baseline data for evaluating repairs would come from the original 3D model of the ship. However, in cases where a 3D model doesn’t exist or isn’t available to the shipowner, the damage can be evaluated by visual inspection. To determine the extent of corrosion, however, requires use of ultrasonic equipment to take point-by-point measurements. Laser scanning and photogrammetry, which creates a 3D model out of a series of digital photos, are also now being used to model all or parts of a ship after it is built, Mr. Larkins pointed out.

“Repair traditionally has been a 2D business,” said Mr. Larkins. “And even if you had more complex stuff, traditionally it was deemed more cost effective to have somebody who’s really really good at what they do to create drawings by hand or just use Autocad, rather than using a 3D model.” In the last five years, however, laser scanners have dropped in price from about $100,000 for one capable of scanning a ship accurately to around $25,000, making them much accessible to smaller shipyards. Meanwhile, Autodesk, the parent company of Autocad, is investing heavily in incorporating scanning technology into its products. “The amount of money they’re putting into it exceeds anything that anyone in our industry could put into that, but it all just comes with our package because we are part of the Autodesk family, Mr. Larkins said.

Scanning also of value in retrofits

Laser scanning is also used in preparing for vessel retrofits, Dr. Cabos pointed out. For example, a shipowner who wants to add new components, such as for ballast water management, would need to identify where to install that equipment. “And for that you would need a detailed and reliable measurement of the actual situation on board,” he said. “And when no 3D models are available, which is typically the case, there are specialized companies that can perform laser scanning of that area.” Dr. Cabos initially thought that 3D modeling for ship repair would be of greatest interest to owners of older vessels. After all, they are more likely to have problems needing repair. It turned out, however, that owners of new vessels are much more interested because the 3D software enables them to track progress from Day 1. “In fact, even a Day 1 inspection right after delivery, or in particular, before the warranty period terminates, is very valuable to the owner,” Dr. Cabos said. “Because a baseline inspection enables the owner to determine whether a defect already existed at the time of delivery.”