Erosion of natural river banks by boat-generated waves is an increasingly serious problem on the navigable reaches of many rivers, particularly on the middle and estuarine reaches. An experiment designed to link bank erosion rates with easily measured wave characteristics, conducted on the scenic lower Gordon River in Tasmania, provides information useful for river management. Within a boat-generated wave train a number of characteristics were measured and most showed a high correlation with measured rates of bank retreat. Maximum wave height within the train is the simplest measure and is associated with a major threshold in erosive energy on unconsolidated sandy alluvium at wave heights of 30 to 35 cm. At maximum wave heights above 35 cm all but the most resistant bank sediments erode.Reducing maximum wave heights to < 30cm by limiting boat speeds, and reducing the frequency of boat passages, caused a dramatic decline in bank erosion along the river.

of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

No abstract

The use of unmanned underwater vehicles (UUVs) to enhance the military capabilities of submarines and to reduce their operational risk is being considered by navies around the world. However, a major difficulty with the operations of UUVs is their recovery back to the submarine at the end of the mission. Various schemes have been proposed by a number of organisations working in this field; however, they all have major drawbacks.A simple concept is proposed based on a warp from the submarine to a low aspect ratio wing, similar to an otter board used by fishing trawlers. This approach allows the submarine to recover the UUV by slowly overtaking it. This is done at a sufficiently large transverse distance between the vessels where hydrodynamic interaction between the two is minimal, with the submarine travelling at a speed at which it can be safely controlled.