FROM PREVIOUS PARTS of this article it will be remembered that, as the fast slipway boat (FSB) is made of steel, her hull is built upside-down until plating is complete. Here (Figs I and 2) the second of the two prototype FSBs building at Fairey Marine can be seen being turned right way up, supported by cranes. Fig 1 gives a good view of the interior of the bare hull with its five watertight bulkheads.

Meanwhile, work has been progressing on the first boat. The decks and wheelhouse superstructure are fitted (Fig 3) and the after cabin superstructure is waiting to go on; all are of aluminium alloy. It is these lightweight, watertight superstructures which will provide the buoyancy to give the FSB her self-righting capability.

Ventilation which will not compromise watertightness is of first importanceand the engine room ventilation trunks are already in place. These are large, square, horizontal trunks built athwartships- as high as possible under the after end of the wheelhouse deck; and they cross so that the ventilation trunk from the starboard side of the engine room has its outlet to port while the trunk for the port side has its outlet to starboard.

In this way, even should the boat be knocked down, water can only rise in one trunk at a time (and it cannot reach the engines), while vital air can still enter freely through the other.

(to be continued).