|Boy's Manual of Seamanship and Gunnery|
Lead Line Instruction
Q: What is a lead line ?
A. A line to which a leaden weight is attached, for the purpose of ascertaining the depth of water a ship is in ?
Q. How many descriptions of lead lines and leads are there ?
A. Two, the hand lead and line, and the deep-sea lead and line.
Q. What is the use of the hand lead and line ?
A. It is always used when a ship is approaching any anchorage, or is cruising in shoal water where the depths to be obtained are expected to be less than 20 fathoms.
Q. When is a deep-sea lead and line used ?
A. On approaching the land, when the true position of the ship is not known for certain, and the depth of water is very great. The bottom of the deep-sea lead is hollowed out; when used, this hollow is filled with tallow (which is termed arming the lead), so when it comes in contact with the bottom, any small substance will stick to the bottom of the lead, such as gravel, sand, small shells, &c. ; it will also denote a hard or soft bottom. On approaching the land, deep-sea soundings are taken at regular intervals ; and the depth of water and the nature of the bottom is entered in the ship's log-book, which enables the pilot to judge what coast the ship is on, also to tell how far she is from land.
Q. How do you know, by the hand lead and line, what depth of water you are in?
A. The hand line is 20 fathoms in length, and is divided into 20 equal parts, called marks and deeps.
Q. How many marks and deeps are there?
A. Nine marks and eleven deeps.
Q. Name the marks.
A. 2, 3, 5, 7, 10,13,15,17, 20. 2, 3, and 10 are distinguished by pieces of leather. 2 has two ends to it ; 3 has three ends to it ; and 10 has a hole in it. 5 and 15 fathoms are distinguished by a piece of white buntin ; 7 and 17 by a piece of red buntin ; 13 by a piece of blue buntin ; and 20 by two knots.
Q. Having learned the marks and deeps, how will you call them, supposing, for instance, you have 9 fathoms, or any of the following marks or deeps :-7, 10¼, 11¾ , 5½ ?
If I had 9 fathoms, I should call by the deep 9.
If I had 7 fathoms, by the mark 7.
If I had 10¼, and a quarter ten.
If I had 11¾ a quarter less twelve.
If I had 5½ and a half five.
Q. What is the first thing to be done on going into the chains to heave the lead ?
A. See the breast ropes properly secured, the line clear, and the end of it fast in the chains ; measure the distance from the chains to the water with the lead line.
Q. Supposing it was a dark night, how would you know what sounding you had ?
A. If more than 15 fathoms, I should reckon from 20 fathoms or the two knots, the length of line that passes through my hand, also the number of pieces of buntin; if under 15 fathoms, I should reckon in a similar way from 10 fathoms, which I should readily know by a piece of leather with the hole in it ; if under five fathoms, the piece of leather at 2 and 3 would be my guide ; so I could always determine the real depth of water by reckoning the distance between either of these marks, and the depth obtained. For instance, if I obtained 13, it would be the next piece of buntin to 10, or the leather with the hole in it ; if 17, it would be the piece of buntin nearest 20 ; or the two knots ; if 5, it would be the nearest buntin to the piece of leather denoting 3 fathoms.
Q. What is the weight of a hand lead ?
A. From 7 to 14 pounds.
Q. What is the weight of a deep-sea lead ?
A. 28 pounds.
Q. How is a deep-sea line marked, and what length is it ?
A. It is usually 100 fathoms long, and is marked exactly the same as the hand line, up to 20 fathoms. At 25 fathoms, 1 knot; at 30, 3 knots ; 35, 1 knot; 40, 4 knots ; so on, up to 100, between every 10 fathoms 1 knot ; and at 50, 60, 70, 80, 90, and 100 fathoms, 5, 6, 7, 8, 9, and 10 knots.
Q. How are soundings obtained by the deep-sea lead ?
A. The deep-sea lead line is kept on a reel ready for use. When required, the reel is taken aft, and held by two men; the end of the line is then passed out on the weather side, and taken forward on the weather bow outside, and clear of all rigging. The quartermaster having ascertained the lead is well armed, it is bent to the line, and a careful hand holds the lead ready for heaving ; a number of men are ranged along outside the weather side of the ship at certain intervals, each with a coil of the deep-sea line in hand. All being ready, the officer of the watch gives the order to stand by as a caution to all, and then to heave, when the man on the weather bow throws the lead as far forward as possible, and calls out " watch there, watch," which is, repeated by each man as the last fake of the coil goes out of his hand. It then runs off the reel, which is held in a convenient position not to stop it until the lead is on the bottom, or sufficient line is run out to show there is no bottom, with the length of the line ordered. A quartermaster, or an experienced leadsman, always attends aft to ascertain when the lead touches the bottom, which he does by allowing the line to run loosely through his hand. When the lead touches the bottom, the line is checked and brought up and down, to ascertain the correct depth, which is noted by the officer of the watch in the log. The line is then hauled in and reeled up ready for use again. When the lead is inboard. the arming is examined, and the nature of the bottom is also noted in the log, and the lead is re-armed ready for use. Before taking a cast of the deep-sea lead, the way of the ship through the water is checked as much as possible
N.B. There are two descriptions of deep-sea leads-the patent, and common deep-sea lead.
Q. How is lead bent to the hand or deep-sea line ?
A. In the end of the line there is always a long-eye spliced. In the upper end or top of the lead there is a hole, through which a becket is worked, the eye in the end of the line is passed through the becket, and over the bottom of the lead, and hauled taut up to the becket again.
Q. How is a deep-sea lead and line hauled in ?
A. A small snatch block, made for the purpose, and fitted with a tail, is attached to one of the quarter davits, or any other convenient place, the line is then placed in the snatch, and walked in by a portion of the watch
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