22 GENERAL NAVIGATION. 



The route should be planned for normal conditions of weather, 

 with suitable variations where necessary in case of fog or bad 

 weather or making points at night, the courses and distances, in case 

 of regular runs over the same route, being entered in a notebooli for 

 ready reference, as well as laid down on the chart. The danger 

 circles for either the horizontal or the vertical danger angles should 

 be plotted, wherever the method can be usefully employed, and the 

 angles marked thereon ; many a mile may thus be saved in rounding 

 dangerous points, with no sacrifice in safety. Ranges should also be 

 marked in, where useful for position or for safety, and also to use in 

 checking the deviation of the compass by comparing, in crossing, 

 the compass l^earing of the range with its magnetic bearing, as given 

 by the chart. 



Changes of course will in general be made with mark or object 

 abeam, the position (a new " departure ") being then, as a rule, best 

 and most easily obtained. The alidade, kept set to the ship's mag- 

 netic heading, should be at all times in readiness for use, and the 

 chart where it may be readily consulted by the officer of the watch. 

 The sextant should also be kept conveniently at hand. 



A continuous record of the progress of the ship should be kept by 

 the officer of the w^atch, the time and patent log reading of all 

 changes of course and of all bearings, especially the two and four 

 point bearings, with distance of object when abeam, being noted in 

 a book kept in the pilot house for this especial purpose. The ship's 

 reckoning is thus continuously cared for as a matter of routine and 

 without the presence or particular order of the captain or navigating 

 officer. The value of thus keeping the reckoning ahvays fresh and 

 exact will be especiallj^ appreciated in cases of sudden fog or when 

 making points at night. 



Wliere the coastwise trip must be made against a strong head 

 wind, it is desirable, with trustworthy charts, to skirt the shore as 

 closely as possible in order to avoid the heavier seas and adverse 

 current that prevail farther out. In some cases, with small ships, 

 a passage can be made only in this way. The important saving of 

 coal and of time, which is even more precious, thus effected by skill- 

 ful coast piloting makes this subject one of prime importance to the 

 navigator. 



Change in the variation of the compass. — The gradual change 

 in the variation must not be forgotten in laying down on the chart 

 courses and positions by bearings. The magnetic compasses placed 

 on the charts for the purpose of facilitating the plotting become in 

 time slightly in error, and in some cases, such as with small scales or 

 when the lines are long, the displacement of position from neglect of 

 this change may be of importance. The date of the variation and 



