The water drag of a hull is reduced by coating the outer surface with a fibre pattern, with the fibres laid flat to reduce drag. Conductors are incorporated into the support layer for the fibres to apply a positive charge which is opposite to the charge in the water. The HT is applied by a control system (11) which has a magnesium cathode. The positive charge can be applied either by wires embedded into the adhesive layer of the fibres or by using a conducting adhesive. The fibres are laid into the required pattern during application by rollers.
