as follows:(a) Occupational diversity. The very diverse skilled tasks which need to be carried out to construct a ship have not been broken down to be performed by semiskilled operatives. On the other hand considerable specialization has taken place so that about 2o different trades are involved in production (excluding specialist sub-contractors) as well as a number of different types of semi-skilled workers and labourers. In practice many of the skilled trades are internally differentiated so that members of them are doing completely different sorts of work. In one sense it can be said that there are no shipbuilding workers, only shipwrights, platers, etc., though in another sense this is not true.(b) Socialization. The entry to all the skilled trades is by apprenticeship for a period of five years. Although under the new Shipbuilding Industry Training Board scheme actual training time is only four years and the training involved has been changed and formalized a good deal, most of the period of apprenticeship is still spent acquiring the skills of a particular trade.(c) Trade Unions. Trade unions in the industry are powerful and control a number of important aspects of the work situation–especially recruitment to a trade through apprenticeship and the apportionment of work. Traditionally each trade or group of related trades was organized in its own trade union. In addition semi-skilled workers and labourers were organized by one or more of the general unions. Recent amalgamations, notably of the boilermakers, shipwrights, and blacksmiths have reduced the number of unions involved in any one shipyard, but even so in the Wallsend yard manual workers are represented by some nine different unions.(d) Market situation of the firm. Though the demand for ships has been growing since the war, it can fluctuate quite markedly in the short run. Orders may suddenly increase due to a crisis like the closure of the Suez Canal, or fall off due to a recession in world trade. Competition in the industry is on an international scale, though many nations give their industry some measure of protection or commercial advantage. The individual shipyard, which in Britain tends to be limited to the construction of only a few ships at any one time, may experience even more marked fluctuations in work available to it.(e) Market situation of the shipbuilding worker. Fluctuations in the demand for ships in any one shipyard or in any shipbuilding area obviously lead to fluctuations in the demand for labour. The market situation of the shipbuilding worker is also affected by two other factors. Different numbers in different trades are needed at various stages in the production of a ship; the demand for the metal trades is greatest in the early stages, particularly up to launching; outfitting on any one ship commences before launching but tends to increase afterwards only to cease suddenly and completely when the ship is completed. It is almost impossible for any one yard to obtain and programme work which makes it possible for them