Many ingenious mechanical methods were used by hydrographic surveyors for measuring the depth of water in the early part of the 20th Century. These were superseded by echo-sounding and sonar techniques in the later decades. Relatively few of the mechanical methods were used by merchant ships but, in the years before radar and satellite navigation, they, and the increasingly popular echo sounder, had a useful place in the navigator's armoury of navigation aids. This paper is not intended to provide a detailed description of the development of sounding devices. Sections 1 to 5 simply outline the principles of the sounding devices with which the authors were familiar during their time at sea. In Sections 6 to 9 the authors recount their anecdotal experiences of the way in which they, personally, used depth measuring devices during the middle years of the 20th century.
This paper presents the thoughts and experiences of marine navigators of the mid-20 th century in their use of compasses during the transition from magnetic to gyro compasses.2. Magnetic compass. I N T R O D U C T I O N.In the mid-20 th Century, ships' magnetic compasses had hardly changed in design or construction since Victorian times. Gyro compasses, on the other hand, were comparatively new devices and were by no means installed in all ships, even relatively large ships. This paper is a collection of firsthand experiences in the practical use of compasses during the period in question.Old sailors' tales, if you like. M A G N E T I C C O M P A S S E S.Magnetic compasses of the time were often mounted in shrines of teak and polished brass. The purpose of these binnacles was to support the gimbal system in which the compass bowl was slung, to provide lighting for night-time viewing of the compass card and to house the system of correctors. These included horizontal and vertical permanent magnets, a pair of soft iron spheres and a vertical, soft iron Flinders' bar. Every few years, a compass adjuster would swing the ship to adjust the correctors and compensate for the deviating effect of the ship's steel structure on the compass. On leaving the ship, he would hand a deviation card to the captain, setting out the residual deviation on all headings of the ship. This would normally show that the residual deviation was zero on all headings except, perhaps, half a degree on southwest, to show that the compass adjuster was a mortal being despite the apparent magic he had performed. Mortal, he might or might not have been, but his deviation card would have no relationship with the real world whatsoever. However, it was routine for us to check the compass error by Sun or star bearings at least once on each watch, and more often if the ship made a significant change of heading, so we soon discovered what real deviations the adjuster had left us with.
Every sailor, at the back of his or her mind, is aware that the nearest land is likely to be directly beneath the ship's keel and he or she is interested to know just how near. For over two thousand years, mariners measured depth of water by using a sounding rod in shallow areas and the lead and line in deeper water. This paper considers how, during the "Dark Ages", sailors in the North Sea might have navigated, including the use of sounding rods and lead lines for way-finding during a time when no other navigational instruments were available. Because of the lack of contemporary records the authors firstly consider the use of depth finding in earlier and later times to shed light on how the early North Sea sailors might have operated. The latter part of this paper takes account of the earlier discussion, together with some records of North Sea voyaging, to suggest how "Dark Age" sailors might have used sounding rods, the lead and line, and other techniques to navigate around and across the North Sea.K E Y WO R D S 1. Lead Line.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.