wartsila new headings in ship design

New Headings in Ship Design

Ship design is undergoing a period of full-throttle advancement, thanks largely to new-generation software tools and smarter approaches. The latest innovations are bringing about vessels that run leaner, cleaner and safer than ever.

Text: Steve Roman Photo: Wärtsilä

If there is one factor that determines the focus of today’s innovations, it is customer preference, says Ove Wilhelmsen, General Manager Sales at Wärtsilä Ship Design. And on this score, ship owners have made their demands crystal clear: “What we have now is a big movement towards more environmentally friendly solutions and lower fuel consumption.”

An obvious place to start is the ship’s fuel type, and here Wilhelmsen notes the growing shift from systems relying on diesel or HFO to cleaner alternatives such as LNG, not to mention the migration to dual-fuel options. He also predicts that hydrogen fuel cells could become a favoured choice in about a decade once the safety and regulatory issues have been tackled.

A farther-reaching improvement, however, has been in the power configurations of the ships – namely, the electrification of both the propulsion systems and the on-board machinery. Unlike a traditional setup where a large diesel engine drives the propeller, the newer systems are configured much like hybrid cars. An electric motor drives the propulsion system, either alone or as a boost function along with an optimised diesel engine, and there is an on-board battery bank that is charged when the ship has an excess of power and fills in when extra power is needed.

“We have seen different power configurations, but what we have seen lately is a lot more batteries. We evaluate batteries for most of the vessels we design now,” Wilhelmsen said. Critically, this approach can lead to even more savings when traditionally hydraulic machinery like winches and fish pumps are replaced with electric equivalents – a trend that is picking up pace as new equipment is being developed. “Every time you convert from one power source to another, you will have some loss, so if you can make as much as possible electric, you will have less loss,” Wilhelmsen explained.

Run silent, run safe

Ship owners and designers have also become aware of the strong link between crew comfort and work performance, particularly in how better sleep can reduce accidents. The latest approaches in design put more emphasis on noise reduction.

“A lot of it is about the arrangement,” said Wilhelmsen, “where you put the wheelhouse and the cabins in relationship to the engine room and bow thrusters.” Some ships are using their bow thrusters constantly to stay in position. So switching to a new type of RPM-controllable thruster can go a long way in dampening the sound.

Material choice can also help. Using concrete, floating floors and insulating materials while avoiding steel can further reduce vibrations and improve the quality of life on board.

The game of compromises

One of the most fundamental – and complex – areas of ship design has always been finding the right hull shape for the specific need. This process of ‘hull optimisation’, as it’s called, is critical for efficiency and performance. With a cargo vessel, for instance, having a larger vessel will let you haul more containers, but it will require more installed power and consume more fuel. You can make the hull long and narrow to increase speed, but then you lose stability. You can make it deeper to increase cargo capacity, but you won’t fit it into shallower harbours. It’s all about compromising to find the optimal shape.

“You need to evaluate this versus that all the way through,” said Wilhelmsen. It’s here that software advances in Computational Fluid Dynamics, or CFD, have been making an enormous impact.

“Earlier, when you designed a hull, you made a lot of assumptions. You did a lot of manual work, and then you tested the performance in a model tank. Today we analyse, we simulate and more or less build a model in the computer and test that model. And it’s very, very accurate,” he said, adding that because the computerised testing is done on 1:1 scale, it’s actually more accurate than the model tank and takes two or three days as opposed to a month.

It’s this ability to optimise hull lines, aided by the latest software tools, that helped Wärtsilä land a contract last year to build what will be the world’s largest krill fishing factory vessel for China-based Jiangsu Sunline Deep Sea Fisheries, as well as the world’s most efficient pelagic trawler for a Scottish customer.

Crazy ideas

Computerised testing also gives engineers the ability to push design parameters to their ridiculous extremes in hopes of gaining new insights.

“It gives you the freedom to test out more wild and crazy ideas,” said Wilhelmsen. For example, his team have toyed with the idea of fishing vessels that look like submarines, with only a bit of superstructure above the surface and the rest fully submerged.

“Of course, it’s not really going to happen, but you can find out something really interesting by being able to do this,” Wilhelm­sen said. Like the concept cars at auto shows, these models will never make it into production but can provide interesting ideas and improvements later down the line.

As helpful as the design software is becoming, it still has its limits, Wilhelmsen cautions. “Of course, the new tools have made it much easier to see if you’re on the right track and you can get the feedback much more quickly, but it’s not a purely computer-based thing. You need some people with seniority and some people with history. You need people with passion for ships.

“It’s like an architect when he designs a new house. Some people have it. Some people make square boxes. Some people do a little bit extra. And that really makes the difference.”

CFD ferry aerodinamics - Ship design speciality software has been propelling the shipbuilding industry.

Digital Evolution

Speciality software has been propelling the shipbuilding industry ever since the early 1960s, when automated plate cutting first came to shipyards. In the decades that followed, programs were developed for other design applications like steel structure engineering, piping, electrics and automation, stability, hydrostatistics, hydrodynamics and placement of deck equipment.

This set-up has historically been problematic, according to Sigurd Underhaug, General Manager IM and Process Development at Wärtsilä Ship Design. “To make a ship, you needed 10 different kinds of software, and transferring information from one system to another has been a challenge.”

But the industry is now undergoing a tidal shift. In the last five years or so, integrated systems that cover multiple disciplines have become all the rage. Wärtsilä uses Siemens’ NX, a popular choice for its strong core technology, and is in the midst of switching from 2D to 3D modelling in its architectural design phase. Though creating the models in 3D is far trickier than in 2D, Underhaug says the payoffs, especially avoiding costly, late-stage design fixes, are well worth the extra effort.

Further integration seems to be on the way: Siemens recently bought CD-adepco, the industry standard program Wärtsilä relies on for Computational Fluid Dynamics (CFD). Replacing weeks of work in testing tanks, CFD technology has already led to significant improvements in hull design, and the pace of change keeps picking up as the software itself becomes more advanced. The latest strategy being developed involves running tests in batches of about 100, each with hull parameters slightly altered. The process requires an enormous amount of computing power, but it provides the best shot at quickly optimising a hull to customer requirements.

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