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The Leviathan of the Tankers - Part-1
Twin Screw Diesel Tanker on the lsherwoocl Bracketless System Delivered to the International Petroleum Company
by the Bremer Vullkan Shipyards at Vegesack, Germany.
Source : Pacific Marine Review, Volume 25, March 1928.
THERE is now completed at the Bremer-Vulkan Schiffbau und Maschinenfabrik, Vegesack, Germany, the “leviathan” of water borne petroleum transport - the new, 21,350 tons deadweight capacity, bulk oil carrying motorship C. O. Stillman, built by that firm to the order of the International Petroleum Company, Ltd., of Canada. The design and supervision of this new tanker were entrusted to the Marine Department of the Standard Oil Company (New Jersey), now the Standard Shipping Company, as that organization
has had such an extensive experience in bulk oil carrier design and construction, and themselves at present having in operation the two largest bulk oil carriers yet put in service, the tank steamers John D. Archbold and Wm. Rockefeller.
The new tanker is a twin screw diesel motor propelled vessel, of the two deck island house aft, bridge and forecastle type, with the propelling machinery aft, and constructed structurally upon the latest longitudinal framing principle (bracketless) as developed
under the Sir Joseph W. Isherwood Bart. patents, for the highest classification of Lloyd's Register of Shipping.
The vessel has the following dimensions and characteristics:
Length between perpendiculars ................................................................................................. 565' 0"
Breadth, molded ........................................................................................................................... 75' 4"
Depth (molded) to upper deck..................................................................................................... 44’ 6"
Depth (molded) to second deck ................................................................................................. 29' 6"
Depth (molded). designed-operating ........................................................................................ 31' 0"
Draft (extreme from bottom of keel plate outer straps amidships), designed operating ....... 31' 2 3/16"
Draft, extreme to Lloyds summer freeboard (approx) ............................................................... 32' 41/2"
Rise of floor .................................................................................................................................... 6”
Radius of bilge ............................................................................................................................... 5' 0"
Tumble home (from 30ft. Oin. to 44ft. 6in.) .................................................................................. 6"
Camber of beam (in 74ft. 4in.) ..................................................................................................... 0' 4"
Sheer at after perpendicular ........................................................................................................ 6' 0"
Lowest point of parabolic sheer - at mid length between perpendiculars.
Height between decks (molded) at all points from upper deck to the forecastle, bridge
deck, and after house tops .......................................................................................................... 7' 6"
Displacement (with shell and appendages to 31ft. 0in. molded water line; at 35 cubic
feet per ton of 2240 pounds), tons .............................................................................................. 31,000
Block coefficient (molded) On length and displacement between perpendiculars to the
31ft. 0 in. molded water line ......................................................................................................... 0.8162
Tons per inch immersion (water at 35 cubic feet per ton) ........................................................ 89.6
Designed endurance sea trial speed, for vessel on even level to 31' 2 3716” extreme
draft, knots ..................................................................................................................................... 11
Estimated effective horsepower, for foregoing trial speed and draft (from model tank
results) ............................................................................................................................................ 2215
Arrangement of Hull
The arrangement of the vessel has received the careful consideration of the designers, from the viewpoints of economical operation, seaworthiness, maneuverability, reduction of the hazards attendant upon transporting petroleum, and affording those conveniences and appointments for the personnel which tend for safety and comfort.
The vessel has only one complete deck, the upper.
The second deck, forming the bottom of the wing or summer tanks, is located at a height of 15’ 0" below the upper deck and, in way of the cargo oil tank space bunkers and machinery hatch, extends as a flat outboard of the expansion trunk bulkheads and/or machinery space hatch. This deep tween decks in way of the cargo oil tanks space has been arranged to permit of carrying a deadweight cargo of heavy petroleum products entirely within the main tanks, with the wing or summer tanks used when a volumetric or light cargo is carried. The cargo oil tanks total net cubic capacity is such that a complete cargo of 68 degree API
product corresponding in weight to the vessel's deadweight capacity may be carried.
The personnel are accommodated in comfortable quarters arranged in the bridge houses, island house aft, and upon the after tween decks; all messing arrangements, including the galley and bakery, being self-contained in a house upon the upper deck, just
abaft the machinery casings. All superstructure houses and house tops are of steel, as are the passageway bulkheads within the houses. This has been done to minimize wood and like fire hazardous materials.
Auxiliaries
The deck auxiliary machinery, consisting of a windlass and capstan upon the forecastle deck, two warping winches on the upper deck, one forward, and theother abaft the pump room entrance, two capstans on the upper deck aft, a winch upon the after house
top, are all electric motor actuated.
The steering gear is also electrically operated and consists of an electric motor actuated worm and gear driven quadrant, connected to the rudder stock and controlled from the bridge and the after house top by a Ward-Leonard system of electrical control. Manual operation of the gear is also provided in the steering gear space, and for emergency purposes there is a hand wheel operated geared sector and gypsy heads fitted upon the after capstan drive shafts to serve in working relieving tackle.
The navigational equipment is especially complete and includes a Sperry gyro-compass installation. For fire protection a Lux carbon dioxide installation is provided.
Cargo Pumps
The cargo oil pumping system is in keeping with the high class of the other equipment afforded the vessel, and consist mainly of three 360 x 540 x 360 x 610 millimeter packed piston, horizontal duplex compound and“or simple stroke governor controlled mechanically lubricated, steam actuated cargo oil pumps, each having a normal rated discharging capacity of 3000 42-gallon barrels of petroleum and'or water per hour, when operating under a steam pressure at the high pressure cylinders of I80 pounds per square inch and against a discharge pressure of 125 pounds per square inch. These pumpe are of especially substantial and airnple construction and are designed for a working pressure oi aw pounds per square inch.
For stripping purpc-us. there la installed a 12 x 8 x 12-inch vertical. duplex, slide valved, mechanically lubricated, steam actuated cargo oil pump having a normal rated discharging capacity of 640 barrels per hour when operating under like conditions as those indicated for the main cargo oil pumps. The four cargo oil purnps are located in the main cargo oil pump room and are so interconnected and arranged that a most flexible cargo oil pumping arrangement is obtained.
Within the lonvard pump room there are installed two pumpe sirnilar to the stripper pump, one for fuel oil transler from the forward fuel oil compartrnents and the other for ballasting the forward fuel oil tank, cofferdam No. 1 and the forepeak and for handling bilge water from the forward flats and dry compartments.
Structaral Details
The structure of the vessel's hull has been given much consideration by the designers, who, in collaboration with Sir Joseph W. lsherwood. Bart., developed some structural arrangements and details, which it is beleived will afford a moat satisfactory hull to
meet the rigorous service to which it will be subjected in the petroleum carrying industry. The Vensel. although framed longitudinally, is of the "bracketless" type. The detail of long overlaps is especially interesting: the overlap is in the form of a depressed tongue extension, provided on the underplate of an outside strake, the edges of the tongue being cut clear back
of the adjacent inside strake plating seam edges, but rnade fayingto the seam edges in a way of transferse bulkheads. By this arrangement, the plating has a normal external appearance, and if any leakage between faying surfaces occurs, the leakage will be to the outeide; a most important feature to prevent contaminatiion of different products when carried in adjoining tanks. The rivets in way of the overlap are caulked head and point; the laying surfaces are packed at the tongue contour and in way of bulkhead bounding bars and all joints are caulked. All tanks of the vessel have been hydrostatically tested, and from the small bulkhead deflections ohserved under test, and the tlghtness obtained, it would appear that the attention paid by the designers to these details has afforded a most suitable structural arrangement.
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See also : The Leviathan of the Tankers - Part-2