GENERAL NAVIGATIOlSr, 21 



and, where the distances are considerable, her position on the line 

 should be checked at frequent intervals, with recordings of time and 

 patent log. This is desirable even where it may seem unnecessary 

 for safety, because if running by the eye alone and the ship's exact 

 position be suddenly required, as in a sudden fog or squall, fixing at 

 that particular moment may be attended with difficulty. 



The habit of running exact courses with precise changes of course 

 will be found most useful when it is desired to enter port or pass 

 through inclosed waters during fog by means of the buoys; here 

 safety demands that the buoys be made successively, to do which 

 requires, if the fog be dense, very accurate courses and careful atten- 

 tion to the times, the patent log, and the set of the current; failure 

 to make a buoy as expected leaves as a rule no safe alternative but to 

 anchor at once, with perhaps a consequent serious loss of time. 



It is a useful point to remember that in passing between dangers 

 where there are no suitable leading marks, as, for instance, between 

 two islands or an island and the main shore, with dangers extending 

 from both, a mid-channel course may be steered by the eye alone 

 with great accuracy, as the eye is able to estimate very closely the 

 direction midway between visible objects. 



In piloting among coral reefs or banks, a time should be chosen 

 when the sun will be astern, conning the vessel from aloft or from an 

 elevated position forward. The line of demarcation between the 

 deep water and the edges of the shoals, which generall}' show as 

 green patches, is indicated with surprising clearness. This method is 

 of frequent aioplication in the numerous passages of the Florida keys. 



Changes of course should in general be made by exact amounts, 

 naming the new course or the amount of the change desired, rather 

 than by ordering the helm to be put over and then steadying when 

 on the desired heading, with the possibilitj^ of the attention being 

 diverted and so of forgetting in the meantime, as may happen, that 

 the ship is still swinging. The helmsman, knowing just what is 

 desired and the amount of the change to be made, is thus enabled to 

 act more intelligently and to avoid wild steering, which in narrow 

 channels is a very positive source of danger. 



Coast piloting involves the same principles and requires that the 

 ship's position be continuously determined or checked as the land- 

 marks are passed. On well-surveyed coasts there is a great ad- 

 vantage in keeping near the land, thus holding on to the marks and 

 the soundings, and thereby knowing at all times the position, rather 

 than keeping offshore and losing the marks, with the necessity of 

 again making the land from vague positions, and perhaps the added 

 inconvenience of fog or bad weather, involving a serious loss of 

 time and fuel. 



