Almost exactly ten years ago the National Research Development Corporation (NRDC) decided to support Christopher Cockerell's ideas for what soon became known as hovercraft. Since then there have been remarkably rapid developments in marine hovercraft and in other applications of the air cushion principle, and there is little need to remind this audience of what has been achieved during that time. Indeed, the large cross-Channel SRN4, and the smaller new Hovermarine sidewall craft, as well as the recently announced design by Vosper-Thornycroft, all speak for themselves and demonstrate vividly the major strides that have been made within a single decade.

During this period there has naturally been a strong emphasis on development work closely related to specific engineering and design projects, but experimental and theoretical investigations of a more general and basic nature have also been encouraged in this country. It is always difficult to separate clearly research from development and this is particularly so in the first decade of hovercraft.