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ease with which a liner may be warped into its berth. In the case of passenger liner service it is especially desirable that provision be made for the docking of the vessel at any stage of the tide. This also applies to cargo carriers. Any undue delay is reflected in loss of time and of charter money, or reduction in the value of the ship to its owners. It must be borne in mind that the ship itself is probably the most expensive single facility in- volved in the terminal. Tug Service is Required Another item of expense that may develop into serious proportions, mentioned above, is the use of tug boats involved in docking and un- docking. The port captain of one of the largest steamship lines states that on their large vessels often 10 to 12 tugs are required, whereas with wider slips and more room, probably less than half this number would be sufficient; and he states that the tug charges for docking and undocking these large vessels amount to nearly $80,000. a year. Saving of one third of this charge would readily justify a considerable additional first cost. For larger vessels, it should be noted that allowance must be made for breasting floats between vessel and pier or quay, and for swinging floats at the corners about which ves- sels are warped. It is elementary that safe clear- ance must be allowed for, between keel and the bottom. In this connec- tion due allowance should be made for the character of bottom, and to insure that ships will not ground at extreme low tide. Besides the ques- tions of accesibility of berths, hori- zontal and vertical clearances, etc., as briefly discussed, other factors— such as the necessity or availability of supporting anchorage space, the safety from collision or other ac- cident afforded ships at berths, shel- ter from storm waves, may often enter into the design of terminal water areas. Space does not permit going into the pros and cons in the old piers- versus-quays argument. As we have stated in connection with the ques- tion of the general layout of marine terminals—this is a question to be decided upon the merits of each indi- vidual case. Quays or wide piers are undoubtedly desirable because of the more ample land areas available for aprons, tracks, roadways and sheds, but special conditions—such ag re- stricted waterfront, high property values, number of berths required and unusual operating or traffic con- ditions, after make the use of com- paratively narrow piers imperative. Short Piers Not Desirable Short piers will rarely be found de- sirable; long piers will generally be more economical of space (including waterfront), more flexible as to avail- ability to various lengths of vessels, and more economical in first cost. Long piers must, however, have suffi- cient width to keep outboard space accessible for land transportation and to avoid congestion. The design of a quay or pier must be adapted to the characteristics of the ships to use it. ' They must have the necessary sta- bility and strength to resist forces due to docking and mooring, and the strength to carry the proper operat- ing deck loads of cargoes, as well as other forces not directly concerned with operation. Their design must be adapted to the methods and facili- ties for loading and unloading ships. Overall loading requires reasonable landing space and clearance between ship and shed. (To be Continued) v7 Swinging Floats* /000' MARINE REVIEW—March, 1931 Suggests Law to Determine Clearance of Bridges Clearance of bridges for vessels in first class ports should be deter. mined by law, Francis Lee Stuart of New York, consulting engineer of the Hudson river project, declares in a statement issued by the Amer- ican Engineering council which through its committee on bridges, is studying the question of the mini- mum height of bridges over nayig- able waters. The difference in cost between the 185 feet desired by the war depart- ment and the 150 to 160 feet de- sired for the public good in the pro- posed Fifty-seventh street bridge alone would be at least $20,000,000 to $25,000,000, according to Mr. Stuart, president of the American Society of Civil Engineers and rep- resentative of that organization in the Engineering council. He said: “The clearance of the draft of a ship has been fixed by Ambrose channel in New York, and the clear- ance of the beam has been deter- minded by the Panama canal. What is now needed is vertical clearance so that the people of the country could plan to develop harbors and water ways without being uncertain as to the height that would be granted by any particular body in the engineer corps. “From the opinion of many ma- rine constructors, the questioning of practical navigators, it develops that there is no known economic reason why masts on a steamship should be higher than necessary to provide proper rigging for derricks, why ships’ masts could not be telescoped so as to pass under bridges of 150 feet in height.’’ Docking with opposite side of Slip occupied by liner Docking with opposite side of S/ip clear nearputerend ‘ 550 1000 ‘sly ; 550/000 slip. Clearances for warping STUDIES OF SLIP DIMENSIONS F16.6