Evolution not revolution

Abstract

The past year has seen a period of evolutionary refinement rather than innovation in the tug design and construction sector. Of significance is the increasing understanding of correct terminology and the elimination of the confusing term reverse tractor in favour of azimuthing stern drive (ASD), thus distinguishing this type from true tractor tugs. There is also a growing realisation that tractors and ASDs and not only good escort tugs. This article examines markets and describes features of recent tractor and ASD tugs from several naval architects and yards. It outlines research and development and discusses trends in vessel design and specification.