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The Pamphlet Collection of Sir Robert Stout: Volume 64

Some Useful Hints for New Zealand Seamen

Some Useful Hints for New Zealand Seamen

On the Compass, on Cross Bearings, on Charts, on Laying-Off Courses, on the Log Line, on Dead Reckoning and on the Chronometer.

Compass.—A. little extra outlay on good compasses few persons will consider thrown away. When the size of the vessel allows of it, have coe to be used as a standard for giving the courses and taking bearings, &c; and, if you can choose a place for it, find it by moving it along the deck till you get the place of least deviation. Double vertical needles are better than the single flat one with the hole for the cup in the middle. See that they are exactly parallel to the N. and S. line on the card; or, if a single needle, that its centre line is exactly under the N. and S. line. As to size, the preference is given to the 7-inch needles, or even shorter. The chief object in large compasses is to enable the helmsman to steer to degrees, and a more accurate course is thus presumed to be preserved. This, however convenient in practice, is not without danger: for the course steered may deceive by seeming right to the fraction of a degree, but which avails little if the compass itself be wrong half a point, caused by the extreme slowness of the oscillations of long needles compared with short ones. In short, the page 74 question may be thus stated: The smaller a card, the more correctly it points; the larger a card, the more accurately it is read. The (steering) compass card should be distinctly marked to quarter points (unless for very small vessels, for the lively motion of which a liquid compass is certainly the best thing, but would probably be considered too expensive). The pivot point should be exactly in centre of bowl and upright; the lubber line should be true fore and aft, and only one be Drawn in the bowl. The cup should be frequently examined and be kept clean, and the point of pivot—which should be of hard steel-be kept adapted to the cup, not too fine nor too blunt; the former will make it too lively, the latter will cause so much friction as in smooth weather to make the card very sluggish. The Liverpool Compass Committee say, "Reported compass errors are sometimes due to cracked or holed agates, but more commonly to worn pivots, with needles that never had, or have lost their proper directive power;" and "the number of cases which have come before this committee of deviation arising from blunted or worn pivots is such as to leave no doubt that this is a most prevalent source of error and bad steering." Always use a hone to rub the point, and never a file, sand paper, &c. In sea-going vessels, light and heavy cards, with their respective points, are necessary for fine and heavy weather. As to place of (steering) compass, there is generally in small vessels no choice; but get as far as you can from stern post (if iron), spindle of wheel, stanchions, and iron bulkheads. As even wooden sailing vessels have some deviation, it is as well to make a table of it, and keep it in your log or work-book.

For Cross Bearings, avoid if possible objects that are a long way off, and those which are so near as to be quickly changing their bearings; get them as near as possible 8 points apart—and choose well-defined objects. Raper says—"when a vessel tacks, the wind often seems to come round with her; at other times the wind seems to favour the vessel on either tack—these effects are often to be attributed to the deviation of the compass." As in general the deviation affects in the same manner the courses of ships steering the same voyage, it has naturally led to the supposed existence of particular currents where none such existed.

Charts.—All the information concerning the chart, such as scale, by whom the surveys were made, what the soundings are in, abbreviations, &c., will be found under the name; and at the bottom of the chart the latest date up to which corrected. An arrow, feathered on both sides, means "current," on one side "flood," and bare "ebb tide." The dotted line running along the land outside the soundings may be taken to mean "in soundings;" a reference to the chart of New Zealand shews that it means 100 fathoms, and a glance shews the distance off the land; in some places it will be seen that the lead gives very little warning. Outside this dotted line will be seen figures with a line and dot over them, this means no bottom at that depth. In the larger scale charts, viz., those of harbours, the sheet charts of New Zealand, &c., are other dotted lines, e.g.,.——., ......, ....., &c., which will usually be found to mean, the "ten," "five," and "three" fathoms lines, &c. Others again denote banks, low-water marks, Most charts have now the compass Drawn for magnetic instead of true points, and giving also the variation. It may here be noted that whenever bearings are taken they should be at once corrected for the page 75 deviation due to the point of the compass that the ship's head is on, before laying them off on the chart. Directions for laying off Courses, Measuring distances, position by lat. and long., &c., are to be found in all the epitomes. North lat. increases northwards, South lat. southwards, East long, to the right, and West long, to the left. No one should grudge the time taken in getting a cross bearing, for "practice makes perfect," and a readiness in taking and laying off cross bearings is very important. Indeed, it may not be too much to say that neglect of this, and of not using any natural leading marks in navigating along a coast, is the cause of many, perhaps most, of the disasters. This neglect is certainly inexcusable, especially when there is no local knowledge; and it does not want a well-fitted standard compass—a little practice will enable you to get bearings pretty near right from the binnacle (but, of course, always use the standard where there is one). This is so important in coasting that a little more must be said about it. You have to pass a hidden shoal, and shape a course to pass well outside. So far, good; but do not trust altogether to this. If the day is clear and the land near enough, take some cross bearings as you Draw near. These will show how you are going over the ground—or, if there is any conspicuous object nearly ahead or astern, get the bearing which will lead you clear; or, better still, see if there are any two objects in line, or nearly so, that will clear you. Go by these until the cross-bearing of another object shows that you have passed the danger. When the land is indistinct and you are in soundings, use your lead (of course everyone knows that the lead is supposed to be Kept going). Consult your sailing directions to see what dangers you have to guard against, how tides will affect you, what water you ought to keep in, &c. When out of sight of land, give all dangers a wide berth, especially if in doubt about the accuracy of your chronometers or Strength and set of current. In coral waters, where you go mainly by the eye, do not risk anything with the sun in your eyes. The further aft it is, the better for seeing dangers. It is almost needless to say, "always keep a good look-out." When you think of the number of times a man, who has been master many years, has taken his vessel in and out of harbour and along coasts, you will see that if ever he neglects this useful rule, he is pretty sure, sooner or later, to be what is called "caught napping." At the risk of repetition, you are again urged to trust nothing to guess or chance work. "I am sure I am so many miles off that point; and if I steer so-and-so, I shall clear that reef." Don't do this, but take one or two cross-bearings, or get a cast of the lead, or any one of the proper things to be done; but don't guess.

Dead Reckoning.—It may be taken for granted that in some, if not in many, small vessels the Dr is very much neglected; but when out of sight of land it is not easy to see what excuse there is for it. The log-slate should be marked up at least at the end of every watch, and the log written up every day. Perhaps it is not too much to say that in some vessels no log is kept, and when the log-book is asked for the official log is produced. Don't work with a slate pencil, or with a lead pencil on stray bits of paper. It is just as easy to work in a little book (an ordinary copy or exercise book) with pen and ink, keeping each day's work separate, and it may prove very useful for future reference. The log-glass should occasionally be compared with a page 76 watch. The rule for marking the log-line is, that the seconds in one hour are to the seconds of the glass, as the feet in one nautical mile are to the knot of the line, e.g., say your glass runs 28 seconds, then—
Seconds in hour. Seconds in glass. Feet in mile. Feet in knot,
3600. 28. 6075.5. 47.5

When the ship's position is found, and the course to the port bound to, it must be remembered that, to bring this to a compass course, the variation must be applied with the sign the reverse i.e., cast to the left, west to the right; then, if there is any deviation, it must be taken out for this magnetic course and applied as above, When a vessel is "lying to," it will be remembered that the point to be taken for course is the middle one between the points to which she comes up and falls off.

Chronometer.—Choose a quiet place for the chronometer—the nearer the centre of motion the better. Avoid places subject to jars, Draughts, or iron. It is a good plan to lit a block of wood on a beam to receive them, the partitions being padded with horse-hair, &c., and enclose this in an outer case, under lock and key. Before carrying them don to the vessel, see that the gimbals are clamped, and release them as soon as in place. Always wind (by same person) at same hour, in the same steady way, counting the turns, and butting gently, Don't trust altogether to yourself for winding, but let it be someone's duty to remind you of it at a fixed time. Wind first compare after, and when practicable take sights at same time. The best time for sights is when object is near E. or W. The daily second difference of comparisons should agree fairly with the sum or difference of the several rates—this will show you at once if they are altering and after a little experience—if you keep the same chronometer and attend to temperature—you will acquire some facility in arranging accordingly. Chronometers are chiefly affected by temperature, and for vessels going from temperate into tropical regions it were much to be wished that the chronometers were rated for the two average temperatures—this is sometimes done. You work at sea with astronomical time, and an astronomical day is 24 hours, now chronometer neither shows the day of the month or anything over 12 hours, so that when you get out to sea and begin your sights this difficulty meets you. It is easily solved, bring your civil ship's time into astronomical time by the usual rules, to this apply the long, in time by Dr, the result will give the Greenwich time roughly, which shows you how to write down the time shown by the chronometer at sights astronomically. In practice you have only to do this once at the outset (if at all), after that the daily changes are so small that the alterations follow almost insensibly. This advice may seem unnecessary, but a man who had only learnt the school plan of a chronometer, showing so many days, hours, and minutes, would find himself puzzled when he first began work his sights out of sight of land. It is known that chronometers are liable to change their rates when first brought on board, so that when practicable it is better to have them on board a few days before sailing, so that another comparison for rates may be had. Vessels trading, say to the Islands, when from the great difference in temperature the rates are liable to alter, may often be able to get sights with the sea horizon at places where they are lying, and find the page 77 error of chronometers for mean time at place, an interval of some days (a week or ten days if possible) with another lat. will give you the rate-independent of the exact long, of place. This is very useful in visiting places, which like many of the South Sea Islands, are not very correctly laid down; whereas, if these longitudes were used, the results would be from the errors in the longitudes, worse than useless. At such places as can be depended on for being correctly laid down the error as well as the rate will of course be found. By attending to this you can, so to speak, keep a check on your rates without improperly meddling with the errors. If your chronometer runs down,—to start it going again, after winding (lift it out of the partition), give it a smart horizontal circular motion. In a ship sailing to the Eastward she meets the sun and shortens the day; in sailing to the West the contrary takes place. In sailing round the world to the East a day is gained; to the West one is lost.

Thos. C. Tilly, Lieut. R.N.,

Examiner of Masters and Seamen, Auckland.