Wave Added Resistance

By Patrick Hooijmans
Thursday, September 20, 2012

MARIN Unravels Secrets of Wave Added Resistance
 

Model tests for the evaluation of ship designs should not only be performed in calm water but also in waves. MARIN’s new Depressurized Wave Basin (DWB) helps unravel some of the mysteries of wave added resistance.
A ship is usually designed with a focus on its performance in calm water. However, operational conditions should be taken into account, including added resistance due to waves because it is an important factor in the economical performance of a ship.
The sustained speed in storm conditions should be investigated but also the power increase in typical service conditions. And with the trend for an increasing ship size, the latter becomes even more important. In addition, upcoming regulations such as EEDI require a very careful correction for the added resistance during speed trials.
Using large ship models in a 240x18x8 m towing tank can make the difference when trying to understand the secrets of wave added resistance. In the DWB a large ship model of a Very Large Container Ship of about 350 m for instance, can be tested at a model scale ratio of 1 to 30.
In our Seakeeping and Maneuvering Basin (SMB) the scale ratio typically doubles, which means that a 1.5 m wave for the ship would require a 2.5 cm wave in the SMB and a 5 cm wave in the DWB. This increase, in combination with increased measurement accuracy, improves the prediction of wave added resistance in typical service conditions.
A further benefit of the DWB is that only one large ship model is used to perform calm water resistance and propulsion tests, cavitation observations, hull pressure measurements and wave added resistance tests for mild to severe weather conditions. When well prepared, all the tests can be conducted within one week. A ship model can be chosen with large propeller models with a diameter of about 300mm, reducing significant scale effects on propeller blade cavitation and propeller thrust and torque. This provides a high level of accuracy when measuring for instance the wave added resistance. In this way MARIN expects to unveil some of the secrets of wave added resistance.

The Author
Patrick Hooijmans is project manager at the Ships department of MARIN, the Maritime Research Institute Netherlands. MARIN offers simulation, model testing, full-scale measurements and training programs, to the shipbuilding and offshore industry and governments.
Email: p.hooijmans@marin.nl

(As published in the August 2012 edition of Maritime Reporter - www.marinelink.com)

Maritime Reporter May 2015 Digital Edition
FREE Maritime Reporter Subscription
Latest Maritime News    rss feeds

Technology

Torqeedo Introduces New Deep Blue Inboard

Torqeedo now offers a shaft drive version of its 40 and 80 horsepower Deep Blue motor. An electric drive designed for marine use from the ground up, the Deep Blue inboard shares the safety,

Protea to Launch Heavy-Lift Cranes at Nor-Shipping

Protea, a global manufacturer of offshore handling equipment, will launch two types of heavy lift cranes at Nor-Shipping 2015 in Oslo, June 2-5. Tomasz Paszkiewicz,

Inmarsat 3rd Global Xpress Satellite's Launch Delayed

Inmarsat has provided an initial update on the launch schedule for Inmarsat-5 F3 (I-5 F3) following the failure of the preceding Proton Breeze M launch from

Naval Architecture

China, Russia Conclude Naval Drill

Russia and China naval forces concluded their first-ever joint military exercise in the Mediterranean Sea this morning, according to an online news briefing from the Chinese Defense Ministry.

SSI to Showcase New Software at Nor-Shipping

SSI informs it will showcase the latest versions of its CAD/CAM software, ShipConstructor and EnterprisePlatform, at Nor-Shipping 2015, June 2-5. SSI CEO Darren

HMC Helps Fine-tune Damen Offshore Carrier

Damen Shipyards has presented a new shipping concept to the market: the Damen Offshore Carrier (DOC) is specifically designed as a smaller heavy transport vessel suitable for offshore installations.

 
 
Maritime Security Naval Architecture Offshore Oil Pipelines Pod Propulsion Ship Repair Ship Simulators Shipbuilding / Vessel Construction Sonar Winch
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: 0.1372 sec (7 req/sec)