Chapter 6 of 9 · 3019 words · ~15 min read

CHAPTER V.

ASSEMBLING AND PLANTING MINES.

NOTE.—The instructions to be observed by the master of a mine planter in marking out a mine field and in planting mines are to be found in Appendix No. 6.

=The planter detail.=—This consists of the chief planter and 3 noncommissioned officers and 16 privates, distributed in three details, as follows: One noncommissioned officer and six privates on each side of the planter and one noncommissioned officer and four privates aft.

=Tools and supplies.=—The tools and supplies to be taken aboard for the work described are:

On the planter.

Alcohol. Anchors. Axe. Boat hooks. Buoy, key. Buoys, mine. Cable cutter. Cables, multiple. Cables, single conductor. Cable tags. Clips, cable. Cotter pins. Crank handle for automatic anchor. Dry cells. Grappling hooks. Hammers. Heaving lines. Kerosene. Knives, submarine mine. Lamps, alcohol (2). Life buoys (3). Marline. Marlinespikes. Matches. Megaphone. Mines. Monkey wrenches. Nuts. Ropes, mooring. Ropes, raising. Shackles, anchor. Shackles, mine. Shoes, mine-cap. Sister hooks. Spring balance. Stamping outfit. Tools and materials necessary to make Turk’s-heads and joints. Voltmeter. Washers. Waste. Wire, soft-drawn copper. Wrench, socket, for automatic anchor.

On distribution box boat.

Alcohol. Anchors, boat (2). Axe. Boat hook. Boat telephone with connectors and earth plate. Breaker of drinking water. Buoy. Cable tags. Compass, boat. Distribution box. Flags, boat (2). Gasoline (tankful). Green light. Hammers. Heaving lines. Kerosene. Knives, submarine mine. Lamps, alcohol (2). Lashings. Life buoys (2). Life preservers, one for each man. Marline. Marlinespike. Matches. Megaphone. Monkey wrenches. Notebook and pencil. Red light. Rope, raising. Ropes, buoy (2). Shackles. Tools and materials to make Turk’s-heads and joints. Waste. White lights (2).

In each yawl.

Anchor, boat. Anchor line. Boat hook. Heaving line. Life buoy. Life preservers, 1 for each man. Marline. Megaphone. Oars and locks (7). Sounding line.

=Preparing mine cables.=—A reel of single-conductor cable is taken from the tank and placed on a cable-reel frame. A piece 20 feet long is cut off the end to eliminate the part which was above water during storage. The cable for the mines is now unreeled, cut to the following lengths _plus twice the approximate depth of the water_, and each end carefully tagged with the number of the corresponding mine. A Turk’s-head is made on each end.

The mine cables are coiled in figure 8’s. In order to secure uniformity in the size of the coils, they may be coiled on a rack (improvised at the post). This rack is made of one 12-foot length of 4 by 6-inch scantling, crossed at right angles by two 6-foot lengths (4 by 6 inch) placed 5 feet apart. Four 1-inch holes are bored through each of the timbers about 2 feet from each of the crossings, and a 2-foot length of gas pipe is inserted in each hole. These pipes make the form on which the coils are made.

A cable must be coiled for planting so that both ends are free, one to be passed to the distribution box boat, the other to be carried forward on the planter and attached to the mine. This is accomplished by starting the coil about 135 feet from the mine-cap end, the approximate length required to run forward when using a mine planter. The cable is coiled on the form, spreading out the laps at the center to reduce the height at that point, until the entire length is coiled. The outer loops and the center of the figure 8 coil are lashed, leaving the ends sufficiently long to lash the part of the cable remaining uncoiled. The mine-cap end of the cable is then coiled on top of the coil and lashed with the ends of the rope.

Single-conductor cables when coiled should be tested for continuity of circuit and grounds before being placed aboard the planter.

For continuity of circuit the two ends of the cable are connected to a battery and voltmeter in series. If the cable has no break, the reading of the voltmeter should show approximately the same deflection as when the battery circuit and voltmeter alone are in circuit.

To test for a ground the cable is submerged in a testing tank, leaving both ends out. It is advisable, when practicable, to extend a lead from one of the operating boards of the mining casemate to the cable tank. One end of the cable to be tested is connected to this lead and the test made as prescribed for “insulation test” on page 44. The condition of a multiple-conductor cable can be quickly determined by this arrangement. If the above method is not practicable, a dry-cell battery with a mil-ammeter and protective lamp may be installed at the cable tank; or, in place of the mil-ammeter and lamp, a voltmeter placed in series with the battery and cable may be used, the resistance being obtained by the voltmeter method. One side of the battery should be grounded by touching the cable armor or by using an earth plate. In actual service, cable which tests under 1 megohm should not be used; for practice, cable under 10,000 ohms should not be used. If post power is used as a source of energy for testing, the system should be free from grounds. Care should be taken to have the cable ends and battery leads free from grounds and dry.

Cables are raised and lowered into the tank by means of a cable yoke, which consists of an 11-foot length of 4 by 6 inch scantling, with three hooks on the lower side and a ring on the upper side at the center for hoisting. The lower hooks, which are secured to the scantling by a bolt and ring, hook into the lashing on the cable. Washers are placed under the bolt heads to prevent their slipping through the holes.

Swinging or traveling cranes with triplex blocks are used for lowering and raising cable and yoke.

The coils of single-conductor cable are carried aboard the planter, to the aft deck, by the cable detail, or they may be lowered onto the deck by means of the cable yoke and a derrick on the wharf. The cable for mine No. 1 is placed on the starboard side of the aft deck and its mine-cap end is carried forward on the cable racks close to the mines. The other cables, Nos. 2 to 9, inclusive, are placed in succession on the starboard side in the same manner. The cables, Nos. 19 to 10 are placed in succession on the port side, with No. 19 at the bottom. The coils on each side are placed on top of each other. The cable should be removed from the racks when its corresponding mine is being prepared for planting.

At the same time the other apparatus and appliances are carried aboard and placed forward, the proper supply on each side. The anchors are placed as convenient to the forward davits as possible.

Finally, the loaded mines are put aboard. If they contain dynamite they should be protected from the direct rays of the sun by being covered with a paulin.

=Preparing mines for planting.=—The detail on each side of the planter prepares a mine on its own side. The loading wire from the mine is cut to the proper length, a water-tight joint is made with the single conductor of the corresponding cable, and the Turk’s-head is clamped in place, care being exercised that no part of the leading-in wire is caught under the clamp. The cable is lashed with soft-drawn copper wire or secured by clips to the bails just above the ring.

The proper mooring rope is now shackled at one end to an anchor, at the other end to the mine, and is lashed to the mine cable with soft-drawn copper wire at every 5 feet. If automatic anchors be used, the mooring rope is shackled to the mine after the anchor and mine are swung outboard; the lashing of the cable to the mooring rope is omitted.

A rope for raising the mine is cut to the length of 80 feet plus the depth of water. One end is attached to the anchor by an anchor knot or bowline, the other to the mine cable by two half hitches and a seizing of soft-drawn copper wire. It should not be secured at other points.

The mine buoys have attached to them 60 feet of ½-inch rope, which is marked at every 5 feet. The free end is slipped through the maneuvering ring of the mine and tied to the buoy.

When planting mines for practice, marline may be used to seize the raising rope to the cable and to lash the cable to the bail and mooring rope.

A mousing must be put around the upper hook of the differential block to prevent the block from jumping off the hook when the mine or anchor is tripped. The tripping hook of the differential block on the forward davit is attached to the anchor and it is hoisted and swung outboard clear of the rail. The mine is similarly slung from the after davit by its maneuvering ring or by a rope sling through the latter. Both mine and anchor are lowered as close to the water as conditions will permit. A heaving line is bent onto the free end of the mine cable, generally by means of a clove hitch and two half hitches.

The aft detail now removes or cuts the rope lashings of the coil of the corresponding mine cable. A detail sees that the cable and raising rope are held on the gunwale ready for planting. These should not be allowed to trail in the water. A man stands near the mine davit ready to throw the mine buoy clear of the planter when the mine is tripped. (Fig. 13 shows the mine and anchor slung for planting and fig. 14 shows the relative position of the various parts in the water. In these figures the cable should be shown as lashed to the mooring rope.)

=The distribution box boat= should precede the planter to the mine field. The distribution box buoy, to which the anchor rope is fastened by a bowline, to the bight of which the raising rope is secured, is taken aboard at the bow, if the tide is coming in toward the box, and the anchor rope is made fast. The distribution box is then raised by its raising rope and secured in the stern. The boat is thus anchored fore-and-aft, perpendicular to the line of mines, with its bow pointed toward the position of the center mine of the group. If the tide is running out from the box, the buoy should be taken in at the stern, the boat being held in position by the raising rope of the distribution box and then by the multiple cable. The anchor rope is finally made fast in the bow. During the planting of mines a man should always stand ready to slacken away on the anchor rope if necessary.

[Illustration: FIG. 13.—MINE READY FOR PLANTING.]

[Illustration: FIG. 14.—MINE PLANTED.]

If the buoy for the distribution box is not in place, the cable must be underrun, either from shore or from a buoy planted for this purpose. This is done preferably with a yawl. The cable is raised, taken aboard, and placed over a roller or rowlock in the stern. The cable is then pulled in over the stern and lowered over a roller or rowlock in the bow. If the planter is to underrun cable, a cathead is put in place and a snatch block is lowered by a raising rope secured to a hoisting windlass. The cable is placed in the snatch block and the planter moves forward slowly. When it is desired to transfer the cable to a small boat the snatch block is lowered into the boat and the cable removed.

After the distribution box boat has secured the box in position, the lid is removed and the cable is tested as prescribed on page 44. A signal is then raised to indicate to the planter that the distribution box boat is ready for the planting of mines.

=Planting the mines.=—If there be a strong tide, the mines should, if possible, be planted at such time that the planter, in going out toward the line of mines, moves against the tide.

The planter moves out and passes close to the distribution box boat, with the latter to port. As it passes slowly by, a heaving line is thrown by a man forward of the beam to the distribution box boat, whose party immediately hauls in the mine cable, bends on another heaving line, and lashes the cable to the boat. It is desirable to have a second heaving line ready in case the first one fails. If the water be rough the cable end is passed to the boat by a launch.

The planter moves forward to the position to be occupied by mine No. 10. If automatic anchors are used, the distance weight is lowered at the command “Lower weight,” given after the cable is secured in the distribution box boat. As the planter approaches this position the command “Get ready” is given. As the forward davit comes abreast of the position of No. 10 mine, the officer in charge of the planting commands “Let go”; the tripping hook of the mine is released first and that of the anchor immediately thereafter. The mine buoy, cable, and raising rope are then thrown overboard.

(Caution.—The men operating the tripping hooks must be very careful that they stand back of all cable and rope, so that they may not be caught. All others must stand clear.)

The planter turns so that the stern will be thrown away from the planted mine. When the stern is clear of the mine buoy “All clear” is signaled from the stern.

The planter then executes a sweeping circle to starboard, passes to the rear, and comes up with the distribution box boat to starboard. As it moves by, the free end of mine cable No. 9 is passed to the boat and secured as before. The planter moves ahead to a point 100 feet to the left of mine No. 10, and as it crosses the line, plants mine No. 9, swings off to port, circles and comes up from the rear with the distribution box to port, and so on alternately until all the mines are planted.

As soon as a mine is dropped the detail for that side of the planter prepares another for planting. There is ample time to do this while the vessel is turning and planting the other mine.

Two small boats, one on each side of the line, work as follows: As soon as a mine is dropped the boat on the corresponding side moves to it, picks up the buoy, pulls the rope taut, notes the submergence of the mine, transmits the data to the planter, and holds up an oar or a flag in prolongation of the buoy rope. The observers at the ends of the base line take observations on this marker and are thus able to plot the position of the mine accurately. This process is repeated for each mine.

These boats also serve as guides to the planter in dropping mines by holding on to their buoys until the adjacent mines are planted. With automatic anchors the line may not be marked otherwise than in this manner.

After the mine is dropped, the members of the distribution box boat party remove the lashing from the cable, insert the Turk’s-head in the proper slot, make a temporary joint between it and the corresponding conductor of the multiple cable, and telephone to the casemate operator. The latter opens all the power switches on the corresponding operating board, closes switch No. 7 up (this throws D. C. power on the mil-ammeter lead), and then plugs in on the upper jaw of the power switch of the mine under test. If the D. C. voltage be 110, the mil-ammeter should read about 40 mil-amperes; if the voltage be 80, the reading should be about 30. If this test be satisfactory, the joint is made permanent.

For the last mine the telephones are removed from the corresponding conductor, a temporary joint is made in the boat, and the test made as above. By arrangement with the casemate operator the mine is left on two minutes for test. At the end of this time the joint is opened and the telephones put back. If the casemate operator reports the test satisfactory, the telephones are again removed and a permanent joint is made.

When the last joint has been made, the distribution box is closed and the raising rope fastened to its lid. The box is then lowered. This is done by the distribution box boat if it is provided with the necessary davit and power, otherwise it is done by the planter. Generally the anchor rope is made fast to a buoy by a bowline, and the raising rope of the distribution box is secured to the bight of the bowline.

After the distribution box is lowered all buoys are removed except that for the box, and such others as it may be desired to place for marking the ends of lines. The marking boats may remove the mine buoys as they work, provided they are notified from the mine commander’s station that proper observations for plotting have been obtained. Such notification is usually sent by telephone to the distribution box boat.

In time of war decoy buoys judiciously placed would be very useful in deceiving the enemy.