1869.] 



Iron-built Sailing-ship { Glenorchy* 



413 



however, been carefully taken by the captain, and from these he found 

 that the compass had a westerly deviation of one point not shown by the 

 deviation-card. From 7.10 a.m. till 3 p.m. the ship was on the port tack, 

 sailing by the wind but kept good full, her course by the steering-compass 

 being about S.W. by W. During the whole of this time a gale of wind 

 was blowing from S.S.E., gradually increasing in intensity, with thick 

 weather and rain, which cleared only for a little about 1 .30, when 

 land was seen in the distance bearing W.N.W. The lead was cast and 

 35 fathoms found. The captain and pilot consulted the chart, and 

 making what they considered a proper allowance for tide and leeway, came 

 to the conclusion that the land was Wicklow Head, bearing W.N.W. , 

 distant twenty -two miles. 



The ship then stood on the same course till 3 p.m., when soundings 

 were again taken and 25 fathoms found. Orders were then given to wear, 

 but in wearing, and when nearly before the wind, the ship struck and 

 remained fixed on the Kish Bank, about four miles S. of the Kish 

 Lightship. « 



The point at which the ship so unexpectedly found herself was about 

 twenty geographical miles to leeward of that at which the captain and 

 pilot supposed themselves to be. In other words, the ship's actual course 

 was about 28° or 2\ points to the right of her supposed course. To 

 what, then, was the error due ? 



In the first place, it seems impossible to attribute any large part of the 

 error to an insufficient allowance for the effects of tide and leeway. It is 

 true that from 7 to 1 o'clock a spring flood-tide, assisted by a southerly 

 gale, had been running, but this was known to the captain and pilot. 

 They had watched with great care throughout the day the courses, the 

 leeway, and the rate, and, if we may judge from their estimate of the 

 distance run, had estimated them with great exactness. 



The next cause that suggests itself is a deviation of the compass not 

 allowed for. 



The steering-compass by which the ship was navigated was, we have 

 seen, carefully adjusted in the Clyde, and was then nearly correct on a 

 S.W. by W. course. Is it possible that any change in the magnetism of 

 the ship had taken place, as has sometimes been found or supposed in new 

 ships, which would account for the error ? The answer to this must be in 

 the negative. It is certain that any such change in the ' Glenorchy ' 

 would have had the effect of producing an error of the opposite kind, and, 

 had it operated, she would have been found to the south, not to the 

 north, of her supposed course. 



Is there, then, any other cause adequate to produce an easterly deviation 

 on a S.W. by W. course which might lurk concealed and undetected in 

 the process of adjustment and only emerge during the voyage ? To this 

 the answer is emphatically Yes ! The Heeling Error. 



