Abstract: This invention deals with under water towing from a ship having a central ll, the side walls of which are provided with arcuate slideways on which a carriage may run. This carriage has a yoke from which it supports a first pulley over which the tow cable is passed in its run between the thing towed and a second pulley located inside the ship. The yoke is pivoted to the carriage on the same axis as that of the cable run between the first and second pulleys so that the first pulley position is maintained against ship's roll. The carriage moves on the slideways so that the cable run between the two pulleys stays of equal length as the swell of the sea lifts or lowers the ship relative to the thing towed. The whole carriage -- first pulley assembly can be drawn into a well-head frame which can be tilted to free the well-head from obstruction.