The harbour of Cape Town seasonally suffers from resonant water oscillations in various parts of Its basins, particularly during the winter storms. These osclIlations, generally descriptionbed as sewhes and locally known as range, may cause ships moored at the quays to oscillate longitudinally and transversely, and when the movements become large, moorings may be parted or large lateral impacts against the fenders may occur. This paper deals with some of the practical and theoretical aspects of the problem, and a comparison is made between the old and new models and their instrumentation. A short descriptionption is given of the response of moored ships to seiches-a non-linear harmonic problem which has baffled experts for a long time but for which a correct, practical solution has now been developed. All factors such as the influence of the length of the ship with respect to that of the exciting wave, and the ship's position In the wave, are taken into account.
The paper presented the Author's experience gained and the results of his studies due to having been engaged in the design of a number of silo installations of various sizes. Commonly used design formulae and procedures were reviewed and various construction aspects discussed.