Figure 3, on page 114, shows a ship 300 feet long in the lock chamber, with the necessary locomotives on lock walls in positions 1, 2, 3, and 4. Locomotives 1 and 2 are used to tow, brake or hold and to keep the bow in the center of the chamber. Locomotives 3 and 4 brake or hold and keep the stern in the center of the chamber.

The required positions of the chocks on the ship are shown at A and E.

62. The turning center or pivot of the ship is at O, a distance from the bow approximately two-fifths of the length of the ship. The point O becomes the center of turning moments applied by the locomotives. A towing line is shown joining the locomotive No. 1 to chock A. Extend the line 1-A to M. Draw a perpendicular from O to the line 1-A-M, meeting the line at M. The mechanical couple is then represented by the force applied along direction A-1 on the lever OM and will pull the bow to starboard. If there is no bow chock and it becomes necessary to use the nearest chock at B, extend line 1-B and draw a perpendicular from 0 to 1-B extended, meeting at S. The mechanical couple is then represented by the force applied along direction B-1 on the lever OS. In Figures 1 and 2 this will reverse the effect of locomotive No. 1 and will pull the bow to port.

63. If it is necessary use a chock at G, Figures 1 and 2, then 1-G extended will pass through pivot O and the bow can not be pulled to either starboard or port and the motion of the ship through the water can not be utilized to ease the ship over to starboard or to port by pulling the bow to starboard or to port.

64. If it is necessary to use a chock at N, the line 1-N extended will meet a perpendicular from O at P. In figure 1 the lever OP is 60 per cent of the lever OM, the distance N from the bow is 19.0 feet, and in a fore and aft direction the distance is only 13.5 feet. In this figure the effect of the pull of locomotive No. 1 is decreased 40 per cent. If the position of N is 24 feet from the bow the lever OP is reduced one-half of OM and the turning moment decreased 50 per cent. In Figure 2 and Figure 3 the turning moment of line through chock at N will be decreased materially but not as much as in. Figure 1.

65. With reference to stern chock E, a line from locomotive No. 8, Figure 1, through position E extended will meet the perpendicular from O at Q, the resultant mechanical couple being the force applied along line E-8 on lever OQ. If there is no stern chock and it is necessary to use the chock at F, then the mechanical couple is represented by pull along line F-8 on lever OR, and it will be seen that lever OR is only 28 per cent of the length of lever OQ, that is, pull of locomotive

No. 8 is reduced in effect by 72 per cent when using the chock at F, only 38 feet from the stern. The same general condition exists in Figures 2 and 3.

66. The turning center O may vary on different ships to a position one-half the ship's length from the bow to a position one-third the ship's length from the bow, that is, the pivot is not in the same relative position on all ships. Even so, however, the explanation above noted will apply with equal force, the effect of the pull by the bow locomotive being materially reduced when no bow chock is available.

67. The friction discs on the locomotive cable drums are set at 25,000 pounds, but as it is very difficult to maintain an accurate set, it is probable that 40,000 pounds may be reached before the friction discs slip. This necessitates that chocks and bitts have strength sufficient to resist 50,000 pounds. The bow and stern chocks are the most important chocks and are vital to the control of the ship, and any accident to these chocks would be liable to result in severe damage. The bow and stern chocks are, therefore, required to be twice the strength of the amidship chocks in order to provide a strong factor of safety. As may be seen by the "Section" sketch in figures Nos. 1, 2, and 3, the chocks frequently are below the coping of lock wall. This necessitates closed chocks to prevent the locomotive's lines slipping out of chocks and thus out of control and also to prevent damaging the rail, stanchions, and other parts of the ship in line between the chock and bitts, and the cable itself.

68. Each line must have a clear lead from its chock to the bitts to which such line is secured. Any obstructions between line of chock and bitts are liable to damage either by strain on the cable or by the loop on the cable catching the obstruction when paying out. At times hydrants are in the way of such leads, and the hydrants are liable to be broken off by the cable loops. The Canal assumes no responsibility for such damage, as the leads must be clear.

7. REGULATIONS FOR INSPECTION AND CONTROL OF VESSELS

IN CANAL ZONE WATERS

69. There is here published for the information and guidance of all concerned the text of the regulations for the inspection and control (anchorage and movement) of vessels in Canal Zone waters, prescribed by the Governor of The Panama Canal on July 9, 1940, under authority of Act June 15, 1917 (40 Stat. 220; 50 Stat. 191) and Proclamation No. 2412 of June 27, 1940 (5 F. R. 2419), and approved by the President on July 9, 1940 (5 F. R. 3393). These regulations,

consisting of sections 1 to 7, appear below as paragraphs 70 to 76 hereof. Section 8 of these regulations was revoked by Governor's Regulations November 29, 1945, approved by the President on December 15, 1945.

70. (Sec. 1) All existing rules and regulations governing anchorage and movements of vessels in the waters of the Canal Zone are hereby reaffirmed and continued in force during the period of the present emergency, except as modified by these rules and regulations.

(See paragraph 69.)

71. (Sec. 2) The rules and regulations governing the anchorage of vessels herein reaffirmed or promulgated shall be enforced by the port captains of the ports of the Canal Zone. In any case where there are no applicable rules or regulations governing the anchorage of vessels, all anchorage shall be in accordance with the directions of the port captains of the ports of the Canal Zone.

(See paragraph 69.)

72. (Sec. 3) The movement of any vessel between points within the area of a port in the Canal Zone, and the movement, lading, and discharging of explosive or inflammable material or other dangerous cargo shall be under the supervision and control of the port captains of the ports of the Canal Zone.

(See paragraph 69.)

73. (Sec. 4) The port captains and chiefs of customs of the ports of the Canal Zone are hereby authorized to cause to be inspected and searched at any time any vessel, foreign or domestic, or any person or package thereon, within the waters of the Canal Zone, to place guards upon such vessels, and to remove therefrom any and all persons not specially authorized by them to go or to remain on board thereof. (See paragraph 69.)

74. (Sec. 5) Port captains are hereby directed, subject to the approval of the Governor, to take full possession and control of any vessel, foreign or domestic, in the waters of the Canal Zone, whenever it appears that such action is necessary to secure such vessels from damage or injury, or to prevent damage or injury to any harbor or waters of the Canal Zone, or to secure the observance of the rights and obligations of the United States. Pending action by the Governor, port captains are authorized to detain any such vessel and are directed to communicate the facts by the most expeditious means available to the Governor.

(See paragraph 69.)