Question

Explain the reasons why a freeboard less than that usually assigned to a normal ship is permitted under load line rules on a bulk oil carrying vessel

Sketch the load line markings

Answer.

Freeboard is the distance between the waterline and the freeboard deck at mid length. The freeboard deck is the uppermost continuous deck which has means of closing all openings.

Rules allow different freeboards for different ships in relation to their construction and cargo they carry.

An oil tanker is so well subdivided into oil tight compartments that it is reasonable to allow a smaller volume of reserve buoyancy and thus a smaller minimum freeboard is allowed.

With the smaller freeboard, however, there is greater possibility of the decks being awash. This freeboard is therefore assigned on the condition that it is possible to pass from any midship accommodation to the after end without setting foot on this deck. A longitudinal gangway must therefore be fitted.

Loadline (Plimsoll) Marking

The load line mark consists of the following marks

The Summer Load Line indicated by the upper edge of the line which passes through the centre of the ring and also by a line marked S.

The Winter Load Line indicated by the upper edge of a line marked W.

The Winter North Atlantic Load Line indicated by the upper edge of a line marked WNA.

The Tropical Load Line indicated by the upper edge of a line marked T.

The Fresh Water Load Line in summer indicated by the upper edge of a line marked F.

The Tropical Fresh Water Load Line indicated by the upper edge of a line marked TF