Chapter XIV THE USE OF OIL FUEL AT SEA Oil Storage on Ships. BVIOUSLY the double bottom of a ship now used for water ballast is the place in which to carry oil fuel, leaving other spaces free. As each fuel tank is emptied it can be filled with water. Lloyds' Register of Shipping publishes certain rules applicable to existing vessels, which are reproduced in Appendix 4. Both Lloyds and the Board of Trade are placing only necessary safeguards, and are not opposing the use of liquid fuel. Sir Fortescue Flannery states that the peculiarly penetrative qualities of petroleum do not attach to the more viscous fuel oil, which he avers to be as easy to retain as water and by the same class and quality of riveted work. Additional water-tight subdivision is, however, advised as a safeguard against the scend of a half-empty oil tank, but in small or medium ships the usual subdivision is thought sufficient. In fig. 1 is shown the system of storage adopted on the ss. Murex, a vessel with all her tanks adapted to carry either general cargo or refined oil, but not originally planned for using liquid fuel, for which purpose she was converted by the Wallsend Slipway and Engineering Company. There is no double bottom below the cargo tanks, which extend to the skin of the ship, but the bottom is double at A and B below the engines and boilers, and cofferdams, C, D, are put in at the fore and aft ends of the cargo space, and, with the fore and aft peaks E and F, have been arranged to take the fuel oil. Service tanks G and H were placed in the 'tween decks. The flange J is coupled up to the pipe from the store tank, and oil passes by pipes K to the various tanks, whence a pump lifts it to the service tanks, which are OIL STORAGE SYSTEM OF SS. "MUREX.' Fig. 1. FUEL TANKS AND FILLING PIPES. In fig. 3 is shown how the oil fuel is stored in a regular oil tank steamer on the Flannery-Boyd system, the oil to be used being carried in the fore and aft peaks and in the ballast tanks under the engines and in the division bulkheads, the cargo of oil being carried in the remainder of the ship. Between the oil tanks and the remainder of the ship it is considered necessary to place a cofferdam. In a tank steamer the rest of the ship means the engine and boiler compartments. These cofferdams are simply two transverse stiffened bulkheads extending across the ship and properly filled with water as a safeguard against leakage of oil. But in practice these cofferdams are often filled with fuel oil, a practice upon which doubts may be expressed, for apparently this destroys much of the safety intended to be given. Oil fuel is also carried in the double bottom below the engine compartments, which again is a point open to discussion, for it is very properly urged that a vessel might become injured by going aground, and such injury might extend to the inner plating and flood the boiler compartment with oil, to the very serious risk of explosion. It certainly seems sounder and safer practice to exclude oil from both the power compartment bottoms and from the cofferdams, the latter being kept perhaps narrower than they are now. Where the fuel oil is of a specially heavy class, there might not be much risk even if it did leak into the firehold, and good residuum or astatki would be something of a safeguard between the main tanks of crude oil and the boiler room. Be this as may, the presence of a narrow water space outside the oil fuel cofferdam would give a better margin of safety. it The riveting of oil-tight plating is usually 3 to 34 diameters in pitch. Old ships, to be rendered fit for oil carrying, which have rivet spacings of 7 to 8 diameters, may thus have a new rivet put into each spacing. Such ships usually require additional deck beams as a rule. Ships should have not less than eight water-tight compartments, and the separating bulkheads, if oil tanks, ought to be connected directly to the skin of the ship, all possible empty spaces being avoided. Oil is filled into tanks so as to stand 2 feet above the upper deck level in the expansion trunks. The gases driven off from oil are heavy, and tend to settle at the bottom of any space into which they obtain access. A thorough system of ventilation is required to get rid of such gases. Air should be admitted through cowl heads to the upper part of the place to be ventilated and removed from the lower part. It will dilute and carry off the accumulated gas. Such air outlets should have induction openings to assist the current. The general direction of air movement in a ship is from aft forward, and advantage may be taken of this in arranging the ventilation. Great care is needed to joint all oil pressure pipes carefully. The screw threads should be good, and ought to make tight joints with only a little smear of litharge and glycerine, or Venetian red and shellac. Such pipes must not be concealed beneath floor plates, in bilges, or behind casings, but ought to be fully exposed to view, in order that any want of tightness may be easily perceived. An oil cargo being so easily mobile with movement of the ship, it is necessary that the tanks should be full, so that there may be no surging. Hence the use of expansion trunks to permit of this and allow expansion without waste or pressure being the result. Surging plates must be employed in those compartments, which may not be always full, as the fuel tanks, and no compartment should occupy too much of the length of a ship without a bulkhead. Similarly bulkheads are stiffened from one to the other by longitudinal plates, which serve to check any tendency to transverse surging, or scending, to use the nautical term. The ordinary cargo boat, fig. 2, when fitted for fuel oil, is re-riveted when necessary, and the oil fuel is carried in the double bottom, and can be replaced, as consumed, with water ballast. Oil is also carried in the fore and aft peaks. Recent Oil Steamers. One of the latest examples of an oil steamer is the ss. Trocas, which has been fitted for liquid fuel by the Wallsend Slipway and Engineering Company, Ltd., the system adopted being the Flannery-Boyd with Rusden & Eeles burners. The ship is an oil-carrying vessel of 347 feet in length and 45'7 feet beam, and at full load carries 6,000 tons of oil. One of the greater obstacles in the way of fitting old steamers with liquid fuelburning arrangements is the difficulty of constructing suitable spaces to carry the |