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 Tanker designs tailored for specific requirements | KNUD E. HANSEN
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05 August 2014

Leading Danish independent naval architects, designers and marine engineers KNUD E. HANSEN (KEH) has down the years put together a portfolio of tanker designs

Article from TANKER Operator June/July 2014

These include 6,300 dwt (internal project) 14,250 dwt, 16.000 dwt (being re-designed and optimised), 19,999 dwt (pending) and 24,000 dwt IMO II types. The company also offers designs for IMO I tankers and product tankers, for example the basic design package for the Stolt-Nielsen parcel tankers now being built at Hudong Zhonghua. In addition, the company can offer tanker designs, either with coated, or stainless steel tanks. The KEH design knowhow is based on many years of experience mixed with very experienced senior engineers, who were heading up the design work for the Stolt-Nielsen tankers. The company’s senior engineers have been managing chemical and product tanker projects through their previous work at Maersk Ship Design, KEH head of machinery and systems Brian Bender Madsen explained.

KEH is also working on the design of a medium size LNG carrier for undisclosed European interests and has also designed a 14,000 dwt asphalt/black oil/IMO II chemical tanker powered by LNG for operations in Canadian waters (St Lawrence River and the Great Lakes).

The Canadian owner and KEH are currently awaiting quotes from various shipyards to build the vessel. This is a continuation of KEH’s strong market position in Canada, as the company has been involved in specialized designs for operating in the St Lawrence and the Great Lakes. For example, in early 1965, Ralph Misener commissioned KEH to design the largest vessel in the fleet and the company’s first self-unloader. At that time, the deck mounted self-unloading system was unique on the Great Lakes, Madsen said. Taking the 24,000 dwt IMO II type design as an example, KEH said that the design method is based on long term experience on ship design and is undertaken in in cooperation with leading tanker operators.

Using advanced software tools for predicting optimum propulsion power, hull lines, stability, energy efficiency, cargo capacity, segregations and hull structural scantlings, KEH claimed to be able to guarantee a low EEDI.

As an example, the new ultra long stroke 2-stroke engines have to some extent changed the way of designing vessels/hulls, as today the aft part of the vessel is more, or less designed around the main engine with the focus on the interaction of propeller geometry to maintain overall propulsion efficiency.

This design is in compliance with IACS Common Structural Rules, IBC code and OCIMF. The vessel is optimised at the lowest energy consumption for a number of different drafts/cargo capacities considering optimal cargo volume, hull structural mass and ballast tank layout.

An example of a KEH designed tanker in service is the 6,300 dwt IMO II type chemical tanker Inge Wonsild, since renamed Nordic Inge, which was completed in 2005.

When KEH starts to tailor a vessel for a specific owner, the company strongly recommends that the owner collects actual operational data. This data is a very important input to find the optimum design speed for a vessel. Experience shows that in many cases, the optimum design speed is much less than the design speed of an owner’s existing vessels, Madsen said.

With the vessel’s operational profile, KEH is able to run its unique iterative design spiral.

The output files define design criteria, such as:

  • General arrangement
  • Cargo layout
  • Cargo tank configuration
  • Structural configuration and integrity
  • Machinery configuration analysis
  • Optimum main dimension analysis
  • Initial stability check
  • Vessel overall efficiency
  • Future legislation

Given the forthcoming SOx and NOx limitations, owners can gain a big advantage by renewing their fleet now, Madsen warned, as many of KEH’s projects show that retrofitting for compliance for future SOx limits is very costly compared to fitting same equipment on a newbuild.


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