Water stilling for towing tank seakeeping experiments

Abstract

This paper reports on an investigation into the influence of a pre-existing wave environment on ship motion experiments. A method is presented that enables appropriate wave thresholds to be set to ensure consistent, accurate and repeatable results, while minimising waiting time between runs. In addition, the optimal use of a wave dissipation device (or side beach) has been examined to maximise the productivity of the tank by minimising the time between runs. A system has been developed to continuously monitor the water stilling in the towing tank during the time period between runs. The software, written in LabVIEW, provides the towing tank operator with a signal when it is appropriate to commence the next test run. The use of the proposed method and analysis system was examined through a series of monohull head sea tests. It was found that total waiting times between runs may be reduced from the current practice of 10 to 20 minutes to an optimum of approximately 5 minutes without compromising accuracy.

Keywords:

• Model experiments
• towing tank
• seakeeping
• measurement
• water stilling
• wave energy
• error analysis

Additional information

Notes on contributors

G Thomas

Dr Giles Thomas is a senior lecturer at the Australian Maritime College (AMC). He received his PhD in 2003 from the University of Tasmania for his work on the slamming of large high speed catamarans. He is also currently a chief investigator on a collaborative project with Incat and Revolution Design, investigating asymmetric and non-linear loads on high-speed catamarans.

J Duffy

Jonathan Duffy completed his naval architecture degree at the Australian Maritime College (AMC) in 1996. Since 1997, he has been involved in various research and commercial consultancy projects conducted at AMC, lectured undergraduate engineering subjects and is currently working as a research engineer with the AMC Towing Tank, Model Test Basin and Ship-Handling Simulator. Jonathan is currently enrolled in a PhD at AMC on a part-time basis, investigating ship-bank interaction and vessel squat for ship-handling simulation.

G Macfarlane

Gregor Macfarlane is the manager of the Ship Hydrodynamics Centre at the Australian Maritime College (AMC), where he coordinates all activities within the centre’s towing tank and model test basin. His main research interests lie in the field of hydrodynamics with specific emphasis on vessel wave wake. He completed his undergraduate and Masters degrees in naval architecture at the AMC.

J Polmear

John Polmear completed a Bachelor of Engineering (Naval Architecture) degree at the Australian Maritime College (AMC) in 2006. In the final year of his studies, he was involved in the investigation of water stilling in the AMC towing tank. He is currently employed as a naval architect by Austal Ships in Western Australia.