ÆäÀÌÁö À̹ÌÁö
PDF
ePub

BRIEF RULES IN NAVIGATION

FOR THE USE OF CANDIDATES FOR THE BOARD OF TRADE YACHTING CERTIFICATE OF COMPETENCY.

INFORMATION relative to the EXAMINATION of CANDIDATES for CERTIFICATES of COMPETENCY as MASTERS of PLEASURE YACHTS.

1. The examination is purely voluntary, and is to be confined to persons who command their own pleasure yachts. A master of a yacht who is not also the owner is not eligible for examination.

2. Only one description of certificate will be issued, which will entitle the holder to command his own yacht whether foreign going or only cruising within the home trade limits.

The certificate will not entitle the holder to command any vessel except the pleasure yacht of which he is at the time owner.

3. Candidates are not required to have served any specified time afloat, as it is believed that their sea knowledge will be sufficiently tested by the examination they will have to pass in seamanship.

4. Testimonials of service need not be produced.

5. The fee of £2 required for the examination of a master of a foreign-going ship will be charged.

6. In other respects the regulations framed for the conduct of the examinations of masters ordinary will apply to these cases, but applications will have to be submitted to the Board of Trade before authority for examination is granted.

The following are the qualifications required for Masters of Pleasure Yachts :

IN NAVIGATION.-He must understand the first five rules of arithmetic, and the use of logarithms. He must be able to work a day's work complete, including the bearings and distance from one port to another, by Mercator's method; to correct the sun's declination for longitude, and find his latitude by meridian altitude of the sun. He must be able to observe and calculate the amplitude of the sun, and deduce the variation of the compass therefrom. He must know how to lay off the place of the ship on the chart, both by bearings of known objects, and by latitude and longitude. He must be able to determine the error of a sextant, and to adjust it; also to find the time of high water from the known time at full and change. He must be able to observe azimuths and compute the variation; to compare chronometers and keep their rates, and find the longitude by them from an observation of the sun; to work the latitude by single altitude of the sun off the meridian; and be able to use and adjust the sextant by the sun. He must be able to find the latitude by a star, &c. He will be required to answer in writing certain questions as to the nature of the attraction of the ship's iron upon the compass, and as to the method of determining any error arising therefrom. He will be examined in so much of the

laws of the tides as is necessary to enable him to shape a course, and to compare his soundings with the depths marked on the charts.

He must possess a sufficient knowledge of what he is required to do by the Merchant Shipping Acts, and possess a knowledge of the measures for preventing and checking the outbreak of scurvy on board ship. He must be acquainted with the leading lights of the channel he has been accustomed to navigate, or which he is going to use.

IN SEAMANSHIP.-He must understand the measurement of the log-line, glass, and lead-line; and pass a satisfactory examination in the green covered pamphlet issued by the Board of Trade on the rule of the road, as regards both steamers and sailing vessels, and the lights and fog signals carried by them, and will also be examined as to his acquaintance with "the International Code of Signals for the use of all Nations." He must know how to moor and unmoor, and to keep a clear anchor; to carry out an anchor. He will also be questioned as to his knowledge of the use and management of the mortar and rocket lines in the case of the stranding of a vessel; as to managing a ship in stormy weather, taking in and making sail; casting a ship on a lee-shore; and securing the mast in the event of accident to the bowsprit.

He will be examined as to his competency to construct jury rudders and rafts; and as to his resources for the preservation of the ship's crew in the event of wreck.

In cases where an applicant has only served in a fore and aft rigged vessel, and is ignorant of the management of a square rigged vessel, he will only obtain a certificate on which the words "fore and aft rigged vessel" will be written. This certificate does not entitle him to command a square rigged ship.

All candidates presenting themselves for examination for the first time will be required to give short definitions of so many of the terms contained in the list (A.) appended to Circular 517, as may be marked with a cross by the Examiner; also at least eight of such of the questions in list (B.), appended to the same Circular, as may be marked with a cross by the Examiner. THOMAS GRAY.

Definition of Terms in Navigation and Nautical Astronomy. (List A.)

1. Multiplication by Logarithms; p. 3.

2. Division by Logarithms; p. 3.

3.

Day's Work; pp. 3-5.

4. Latitude by Meridian Altitude of Sun; p. 5.

5. Difference of Longitude by Parallel Sailing; p. 5.

6. Course and Distance by Mercator's Sailing; p. 6.

7. Time of High Water by Admiralty Tide Tables; p. 6—8.

8. Amplitude by the Sun, with Error and Deviation of Compass; p. 8.

9. Longitude by Chronometer and Sun's Altitude; p. 9-10.

10. Azimuth by Sun's Altitude, with Error and Deviation of Compass; p. 10-11.

11. Latitude by Reduction to the Meridian; p. 12.

12. Latitude by Meridian Altitude of Fixed Star; p. 12-13.

Use of the Chart and Sextant.

Deviation of the Compass and Use of Napier's Diagram. (List B.)

BRIEF RULES
RULES

IN

IN NAVIGATION.

1.

MULTIPLICATION BY LOGARITHMS.

(Tab. XXIV. of Norie; Tab. 64 of Raper; Tab. 17 of Rosser; also, for Note on Index, see p. 13.)

Write down the numbers to be multiplied, one under the other; take out the Log. of each, and add the two Logs. together; the sum will be the Log. of the product, which take out.

[merged small][ocr errors][ocr errors][ocr errors][ocr errors][merged small][ocr errors][merged small][merged small][merged small]

Under the number to be divided write the divisor; take out the Log. of each, and subtract the lower Log. from the upper one; the remainder will be the Log. of the required answer, which take out.

[merged small][ocr errors][ocr errors][ocr errors][ocr errors][ocr errors][merged small][ocr errors][ocr errors][merged small]

N.B.-In the first place, attentively read the following notes on

CORRECTING COURSES AND BEARINGS:

1. When correcting a Course or Bearing, always suppose yourself standing in the centre of the Compass, looking in the direction of the Course or Bearing.

2. A Compass Course may be affected by Leeway, Deviation, and Variation.

3. A correct Magnetic Course can be affected by Leeway and Variation, not by Deviation.

4. A Compass Bearing may be affected by Deviation (due to the direction of the ship's heading or course), and by Variation.

5. A correct Magnetic Bearing can be affected only by Variation.

6. When correcting for Leeway

Allow it to the right if on the port tack;
Allow it to the left if on the starboard tack;

that is, in a direction from the wind.

7.

When correcting a compass course for Deviation-
Allow it to the right, if Easterly:
Allow it to the left, if Westerly.

8. When correcting a compass course for Variation-
Allow it to the right, if Easterly;
Allow it to the left, if Westerly.

3

Having carefully read over the instructions on "Correcting Courses and Bearings," proceed to correct the Courses in the Day's Work according to the precepts there laid down. Also, note, that all the courses, though given in points of the compass, are to be converted into degrees, and so entered in the Traverse Table.

1. Reverse the departure bearing; express it in degrees, and apply the deviation (due to the direction of the ship's head) and the variation; the result is to be taken as a course.

2. Correct each course in succession, allowing the leeway (if any), applying the deviation (appertaining to each course), and also the variation.

Note.--Allow the leeway in points before expressing the course in degrees.

3. The current being correct magnetic, treat it as a course, but only apply the variation. Note.-The drift is to be taken as a distance.

4. The true courses being thus found, are then, with their respective distances, to be entered in the following form:

[blocks in formation]

5.

fill

Note. In all Epitomes of Navigation the Traverse Tables are 1 and 2.

Enter Traverse Table II. with the several courses and distances, and up the D. Lat. and Departure columns. Remember to read from the top of Trav. Tab. if course is less than 45°, but from the bottom if over 45°. Also, if Dist. exceeds 300 miles, enter the Trav. Table with half the Dist., take out the corresponding D. Lat. and Dep., and then double them.

6. Add together the quantities in the N. column, and also in the S. column ; then, take the difference of the two sums, giving the remainder the name of the greater quantity (N. or S.): the result will be the Diff. Lat. made good.

7. Add together the quantities in the E. column, and also in the W. column; then, take the difference of the two sums, giving the remainder the name of the greater quantity (E. or W.); the result will be the Departure made.

8. For the Course and Distance made good, enter Trav. Tab. II and seek out the page where the D. Lat. and Dep. made are side by side, reading headings of columns from the top if D. Lat. is greater than Dep., but from the bottom if D. Lat. is the less. The course (in degrees) is taken from the top of the page if D. Lat. is greater than Dep., but from the bottom if D. Lat. is the less. The Dist. comes from Dist. column alongside the given D. Lat. and Dep. name the Course according to the D. Lat. and Dep., and write the result thus-Course made good N. or S.. E. or W.; Dist. miles.

...

9. For the Lat. in.--Under the Lat. left write the D. Lat.; if both have the same name (N. or S.) take their sum for Lat. in, of the same name as Lat. left if one is N. and the other S. take their difference for the Lat. in, of the same name as the greater.

10. For the Middle Lat.; add together the Lat. left and Lat. in, if both have the same name (N. or S.), and divide the sum by 2; if one Lat. is N. and the other S., take their difference and divide the remainder by 2.

11. For the Diff. Long.-Enter Trav. Tab. II. with

Mid. Lat. (as a course)

and Dep. in D. Lat. column

the Dist. in Dist. column is the

required Diff. Long.

Note. If Dep. exceeds 300, take the half of it, and having found the Dist. corresponding thereto, double it.

Note.--If the Lat. in is less than 5° the Dep. may be taken as the Diff. Long.

12.-For the Long. in.-Under the Long. left write the Diff. Long. with the same name as the Dep. If Long. left and Diff. Long. have the same name (E. or W.) take their sum for the Long. in, of the same name as Long. left; except this sum exceeds 180°, in which case subtract it from 360°, and mark the remainder W. when Long. left is E., but E. when Long. left is W. If Long. left and Diff. Long. have different names (one E. and the other W.), take their difference for the Long. in, of the same name as the greater.

4.

LATITUDE BY MERIDIAN ALTITUDE OF SUN.

1. For the Greenwich Date.-Write down the Ship Date, month and day, with Oh. Om. Os., under which put the Long. in time; subtract the latter if Long. E., but for Long. W. add. The result will be Green. Date Apparent Time.

2. For the Declination.-Enter Naut. Alm. page I. of given month, and take out the Declination for the Green. Date; for method of correction see p. 14 No. V. 3. For the True Altitude.-Correct the observed Altitude for Index Error (if any), Dip, Refraction, Semi-diameter, and Parallax (see p. 16 No. VI.) The result will be the True Alt.

4. For the Zenith Distance.- -Subtract the True Altitude from 90°; and name the remainder N. when sun bears S., but S. when sun bears N.

5. For the Latitude.-Under the Zen. Dist. write the corrected Declination, each having its proper name N. or S.; if both are N., or both S., take their sum for the Latitude; if one is N. and the other S. take their difference for the Latitude, of the same name as the greater. If Zen. Dist. is 0, the Declination is the Latitude; if Declination is 0, the Zen. Dist. is the Latitude.

5. DIFFERENCE OF LONGITUDE BY PARALLEL SAILING. Under the Latitude write the Departure. To the Log. Secant of the Latitude add the Log. of the Departure, the sum (rejecting index 10) will be the Log. of the Difference of Longitude, which take out.

[ocr errors][ocr errors][merged small][ocr errors][ocr errors][merged small][merged small][ocr errors][merged small][ocr errors]
« ÀÌÀü°è¼Ó »