APL Saves $30M/Year through Hull Optimization

by Cosmin Ciortan, DNV
Tuesday, October 29, 2013
New hull design (image courtesy DNV).

In connection with an order of a series of 10 new 13,800 TEU container vessels from the world’s largest shipbuilding company Hyundai Heavy Industries (HHI), the global container transportation company APL requested DNV Maritime Advisory to cooperate with the shipyard to ensure superior hull efficiency of the vessels.

Optimizing the Hydrodynamic Performance of a Vessel
Ships used to be optimized for the design point (i.e. to give the best performance at the design draft and speed); however, the ship seldom sails in that condition. As a result, APL asked for a different kind of optimization to be performed, this time targeting various speed-draft combinations as described in the operating profile.

The overall hydrodynamic performance of a vessel is directly connected to the resistance and propulsive efficiency. The resistance is influenced by the hull shape, the wetted surface area and the configuration of appendages, while the propulsive efficiency is influenced by the propeller open water characteristics and the interaction between hull and propeller. The performance depends on the variation of operating conditions, i.e. vessel speed, draft and trim.

Vessels have traditionally been optimized for a single condition, normally the contract speed at design draft. With the help of state-of-the-art Computational Fluid Dynamics (CFD) tools and modern computers it is now possible to optimize a vessel for various conditions in which the vessel will be trading.

DNV Maritime Advisory has worked with hull optimization for several years, serving shipowners, shipyards and designers with valuable advice during the design process. DNV’s experts have extensive relevant experience within ship hydrodynamics and energy efficiency, applied to numerous vessel types and sizes including the major segments: tankers, bulk carriers and container vessels.

The Optimization Process

A typical project for hydrodynamic hull optimization may include:
•    Establishing a close dialog between DNV, the shipowner and the shipyard
•    Defining a realistic operating profile
•    Discussing and combining DNV’s design ideas with the yard’s design philosophy to obtain an optimal hull in both a hydrodynamic and building perspective
•    Optimizing the hull forebody based on the operating profile
•    Optimizing the hull aftbody to improve the propulsive efficiency, including consideration on propeller and machinery configuration
•    Assessing the Energy Efficient Design Index (EEDI)
•    Supporting during preparation and attending the towing tank model tests

The delivered value for the ship owner and the shipyard is increased confidence in the hydrodynamic performance of the hull. Typically, considerably improved fuel efficiency and reduced gas emissions are achieved throughout the vessel’s lifetime. In this specific case, the scope of work included:
•    Establishing a weighing matrix for the vessel’s relevant operating profile
•    Optimizing the hull forebody and aftbody (shoulders, bulb, transom stern height, etc.) based on the operating profile
•    Analyzing the wake and propulsion efficiency
•    Predicting the speed – power and fuel oil consumption curves
•    Assessing the preliminary EEDI
•    Attending the towing tank model tests

All simulations of resistance and wake assessment were performed using STAR-CCM+. According to OlavRognebakke, head of ship hydrodynamics and stability at DNV, it is the availability of powerful CFD tools such as STAR-CCM+, combined with the expertise of highly qualified staff which made it possible to enhance Hyundai’s already very good design.

Outcome of the assessment

The hull was optimized for five different design points (different speed-draft combinations). The aft part was optimized for maximum propeller efficiency. In addition, the bulb was lowered to be efficient at lower drafts too. While this solution may result in a marginal penalty at the original design condition, the aim was to optimize the hull for a range of operating conditions. Instead of a design speed of 25 knots, the new vessels were optimized for lower speeds, with a top speed of 23 knots, following the “slow steaming” trend observed in the last years. The overall improvement in energy efficiency was 36%.

Conclusion
By working closely and keeping a continuous dialogue with APL and HHI, DNV ensured that the best ideas and results were combined into the final hull design. It was estimated that the optimized hull will result in annual fuel savings of about $3 million per ship, which amounts to annual savings of $30 million for the whole fleet. These achievements provided positive market attention and ensured improved market positions for both the ship owner and the shipyard. Finally, the cost of the service provided by DNV Maritime Advisory is negligible compared with the savings achievable through improved fuel efficiency. DNV, which is an independent foundation, has entrusted all commercial rights to Hyundai Heavy Industries.

Facts
DNV Maritime Advisory runs fully viscous and potential flow CFD simulations at full scale. STAR-CCM+ and Shipflow are used on a computational cluster with more than 600 CPUs. Several design applications are used, including MaxSurf, NAPA, Rhinoceros, HDef and ShipX. DNV has been carrying out hydrodynamics hull optimization projects in cooperation with major ship owners, world leading shipyards and design offices. Previous projects covered several container vessels ranging from 1,600 to 14,000 TEU, Aframax and Suezmax tankers, bulk carriers ranging from 38,000 to 206,000 dwt and offshore supply vessels.

(As published in the October 2013 edition of Maritime Reporter & Engineering News - www.marinelink.com)


Shipbuilding

MV WERFTEN, Foreship Sign Design Agreements

MV WERFTEN signed a letter of intent with the engineering company Foreship in Stralsund today. The agreement includes parts of the basic design as well as design,

Zumaia Offshore Acqires MPP Workboat Aitana B

In April 2016 Zumaia Offshore, S.L., leading workboat owner and operator based in the Basque Country, took delivery of the Cummins-powered MPP workboat “Aitana

How Rapid is the Fleet Growth?

During July 2016, the containership fleet reached a landmark 20 million TEU in terms of aggregate capacity, says Clarksons Research.   To many it only seems

Ship Repair & Conversion

MN100: Conrad Shipyard

The Company: Conrad Shipyard was established in 1948 and is headquartered in Morgan City, Louisiana. The company designs, builds and overhauls tugboats, ferries,

MN100: TPG Marine Enterprises, LLC

The Company: TPG Marine Enterprises, LLC is an operations, logistics and consulting company that specializes in all aspects of cargo movement on the Inland Waterways System.

Wärtsilä Re-gasification system for Norwegian Ship Conversion

Wärtsilä has been contracted to supply the re-gasification system for an FSRU (Floating, Storage, Re-gasification Unit) conversion project that Höegh LNG plans to carry out on a modern LNG vessel.

Container Ships

Maersk Line's Innovative Smart Reefers

Have you heard about Maersk Line's smart reefers that can listen and talk? Cutting edge technology that reduces risk in customer supply chain, claims Maersk Line.

Rickmers Holding, E.R. Capital Drop Merger Plan

Rickmers Holding AG and E.R. Capital Holding have jointly decided not to pursue the merger of their ship management activities.   For many years the companies

Hapag-Lloyd: UASC Merger Benefits to show in 2017

German container shipping line Hapag-Lloyd expects to reap a third of targeted annual synergies of $400 million from the planned merger with Arab rival UASC already next year,

Naval Architecture

MV WERFTEN, Foreship Sign Design Agreements

MV WERFTEN signed a letter of intent with the engineering company Foreship in Stralsund today. The agreement includes parts of the basic design as well as design,

Zumaia Offshore Acqires MPP Workboat Aitana B

In April 2016 Zumaia Offshore, S.L., leading workboat owner and operator based in the Basque Country, took delivery of the Cummins-powered MPP workboat “Aitana

C-Job Designs Flettner Freighter for Switijnk

The Dutch shipping company family Switijnk has contracted C-Job Naval Architects to develop a Rotor Sail-equipped design to meet their specific loading and sailing profile.

News

MV WERFTEN, Foreship Sign Design Agreements

MV WERFTEN signed a letter of intent with the engineering company Foreship in Stralsund today. The agreement includes parts of the basic design as well as design,

NParks, Keppel in S$2.08 mln Partnership for Restoring Singapore Forest Wetlands

The National Parks Board (NParks) and Keppel Corporation today unveiled plans for a partnership to restore the freshwater forest wetland ecosystem historically

Zumaia Offshore Acqires MPP Workboat Aitana B

In April 2016 Zumaia Offshore, S.L., leading workboat owner and operator based in the Basque Country, took delivery of the Cummins-powered MPP workboat “Aitana

Vessels

C-Job Designs Flettner Freighter for Switijnk

The Dutch shipping company family Switijnk has contracted C-Job Naval Architects to develop a Rotor Sail-equipped design to meet their specific loading and sailing profile.

Damen Trading Sale hits 500th Vessel

30 years and 500 vessels later, Damen Trading is just getting started. Damen Trading’s story begins in 1986, with Damen Shipyards Group responding to growing market demand for used vessels.

Matson Orders Two ConRo Ships from NASSCO

Matson Navigation Company, Inc., a subsidiary of container shipper Matson, Inc., has signed a contract with U.S. shipbuilder General Dynamics NASSCO to build two

 
 
Maritime Careers / Shipboard Positions Maritime Contracts Maritime Standards Navigation Pipelines Pod Propulsion Ship Electronics Ship Repair Ship Simulators Sonar
rss | archive | history | articles | privacy | contributors | top maritime news | about us | copyright | maritime magazines
maritime security news | shipbuilding news | maritime industry | shipping news | maritime reporting | workboats news | ship design | maritime business

Time taken: 0.1515 sec (7 req/sec)