A Treatise On The Principles And Practice Of Harbour Engineering

l8 HARBOUR ENGINEERING have occurred in which boats have become jammed in an entrance through excessive crowding, with, unfortunately, disastrous conséquences. Fishing smacks of the present day have a beam of 20 feet or so, and allowance should be made for, at least, three or four, or even more, entering abreast, according to the size of the fleet. The length of ordinary fishing-boats ranges from 50 to 60 feet, and their loaded draught lies generally between 6 feet and 10 feet; but steam trawlers draw as much as 14 or 15 feet, and their length is rarely less than 110 or 120 feet. In a fishery harbour, broad open quays with a large covered hall, or market, are required for sorting the fish and conducting sales. It has to be borne in mind that under modern conditions of trade, a fishing fleet of steam trawlers most needs be furnished with supplies of coal and ice, and for this purpose railway sidings at the quayside become a necessity. For large vessels of this class, the fishery harbour becomes of a more important character, trenching, in many respects, on the commercial harbour. Seleetion of Locality.—Reviewing the subject as a whole, and postu- lating the choice of a situation for a harbour, the conditions which would govern that choice divide themselves into three heads. First and foremost, there is the obvious advantage to be derived from a position adjacent to some existing means of internai communication, such as river, canal, or railway. In the absence of all these, it is still possible to consider the feasibility of the formation of two of them, and any obstacles likely to prove antagonistic should be carefully weighed and avoided. Then the extent of adverse meteorological and climatic influences claims attention. Fog and frost are dual evils which infest very many harbours to the infinite detriment of their usefulness. The former jeopardises shipping, and both impede navigation. To be ice-locked for several months in a year, like Montreal or St Petersburg, is a serious outlook for any progressive port. The ice-breaker, however, has done much to relax the rigorous grasp of winter, and very few ports need now resign themselves to the entire cessation of their sea-trading operations. For the fog-fiend, there is unfortunately no practicable remedy as yet. Certain experiments conducted in scientific quarters seem to suggest a possible amelioration, but on too small a scale for general application. As regards protection from storms, the value of head- lands and promontories has already been pointed out. Cover should, of course, be sought from the most tempestuous quarter. Lastly, the facilities afforded for providing such artificial protection as is requisite should be taken into account. This constitutes the economical aspect of the question, and some of the numerous matters deserving attention are the length of breakwaters and jetties required, the nature of their con- struction, the source of suitable material, and the expense of carriage, the means of procuring labour and plant, and the resources of the district