22.01.2016

New materials needed for Arctic vessels

It’s no secret that Arctic cargo ships are getting bigger and the ice they are going into heavier, driven by economies of scale and the push to extend the operating season.
This combination of size of ship and type of ice is different from anything engineers have measured before or have experience with. This means there is less understanding of the actual loads these vessels can carry and engineers and designers have to be conservative.

The shipping industry needs to keep an open mind to alternative shipbuilding materials as well as how vessels are constructed.

It’s no secret that Arctic cargo ships are getting bigger and the ice they are going into heavier, driven by economies of scale and the push to extend the operating season.

This combination of size of ship and type of ice is different from anything engineers have measured before or have experience with. This means there is less understanding of the actual loads these vessels can carry and engineers and designers have to be conservative.

For this reason, ships can be overly heavy. Heavy ships mean less cargo carrying capacity. We are also getting to the point where the steel weight of these large ships is a massive proportion of the overall ship weight compared with open water designs. This also influences how much cargo the ship can carry and how it is designed and constructed.  A vessel is much more difficult to construct when there is a lot of steel.

We’re reaching the stage where the designs could become uneconomical or technically more difficult to design.

There are two routes the industry needs to take. One is for scientists and engineers to understand what the ice loads really are on these large ships. The other is to look at alternatives to our standard shipbuilding steels or even the high strength steels – because, although icebreakers have used such steels for many years, questions arise if the same steels are applicable large cargo ships.

We are also getting close to what we can practically do design-wise with standard ship construction configurations. So we need to keep an open mind both to alternative materials and how we construct the ship.

One idea that’s getting a lot of interest at the moment is the use of sandwich panel systems (sps), where a laminate layer is sandwiched between two steel panels. The best application for these, however, is flat panels, whereas the hull of an ice-going ship is curved.

There are other high strength steels in the offshore industry but the loading characteristics of offshore structures are different to ships. We probably need to investigate how far we can push the envelope with these steels we have access to.

But, as for new materials, that’s a question for the material scientists and we probably need to be look outside the marine industry for inspiration.

 

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