Stability is crucial to any type of ship but tugs in particular since this particular ship type every day experiences many challenges that influence stability – some of which in rapid order. During tug operations a number of forces and combinations of forces are working on a tug often at or near their maximum with respect to the tug’s stability. Think of towline, hydrodynamic, steering and propulsion forces, to name but a few. Furthermore, a tug’s stability is not a static condition but can change with every moment. Alterations in the amount of bunkers or stores, water on deck, slack tanks and ice accretion, all complicate the stability situation. These various factors could combine to affect stability in a negative way and may even culminate in a very dangerous situation for the tug. It is therefore necessary for tug masters to have at least a basic idea of the elements of stability.
Tug masters need to know where the limits are and what the consequences could be if the tug or tug handling practices don’t conform to the rules of stability. Not only limited to the normal average day-to-day circumstances but also when extreme conditions such as dense fog and storm occurs. The consequences of mistakes can be very dramatic. In tug capsizes known to have occurred between 2010 and 2015, for instance, more than 45 people have drowned.
This educational guide to stability specifically for tugs aims to provide this important information to tug masters. It is written in a manner readily understood by all tug masters regardless of their education, formal qualifications, nationality or operational background. The text is accompanied by numerous explanatory illustrations and photographs.
In writing this handbook the authors – Capt. Henk Hensen and naval architect Dr. Markus van der Laan – have focussed on the practical aspects of stability, tug design and equipment including the consequences of unsafe procedures. The emphasis is on harbour / shiphandling tugs although several of the topics covered apply equally to seagoing tugs.
The book is thoroughly recommended and should be on board every tug operating in port.
Tug Stability – a practical guide. – Authors: Henk Hensen, Markus van der Laan. Published: 2016. Size hxb 245 x 175 mm. English language. Hardback cover. 110 pages. With glossary of terms, list of references, appendices. Over 70 illustrations (photo’s , graphs, drawings) in colour. ISBN 978-1-904050-29-2. Catalogue price: Euro 33,50. On sale by Polestar Publishing, Lopik, The Netherlands.
