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 These were superseded by echo-sounding and sonar techniques in the later decades.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.
In the middle years of the 20th Century, few merchant ships were fitted with radar and, on those that were, shipmasters often looked upon it as a distraction from a watchkeeper's proper duties rather than as a useful aid to navigation.For shipmasters of that persuasion, the only place to keep watch was outside the wheelhouse on an exposed bridge wing; mostly the starboard wing because the COLREGS (‘Collision Regulations’ or, more properly, ‘The International Regulations for Preventing Collisions at Sea’) required us to give way to ships approaching from the starboard side. Well, the bridge wing was an attractive place to spend a few hours on a calm, tropical night, but it could be highly disagreeable and sometimes, I thought, actually dangerous, in a North Atlantic rainstorm.
Erik Jonsson is an old friend to those of us who have participated in the quadrennial RIN conferences on Animal Navigation. His book provides welcome background to, and expansion of, the contributions he has made at those conferences on the subject of unaided human navigation. What he has to say makes stimulating reading, not only for animal navigation researchers, but also for anyone who has ever considered, introspectively, the seemingly effortless way in which we navigate in the course of our daily lives.Erik has not set out to write a rigorous treatise. At one point, he nostalgically refers to a paper written in 1927. ' Back then, articles in scientific journals could still have charm ; the author was allowed to be delightfully human, somebody who, through his or her writing, could make friends with the reader. ' Erik writes in just such a relaxed, and even lyrical, style, so much so that he slips easily into actual verse from time to time. The references are unusual in that they list only the author and date, but the bibliography covers all the references and includes enough information to trace the original sources.This book is not, then, a place to look for descriptions of controlled experiments and analyses of their results. Where it does have a scientific element is in the author's ability to generate hypotheses for explaining the impressive navigational abilities of humans. Erik is well aware of this, and suggests ways in which his hypotheses might be tested. He even describes some impromptu and wildly uncontrolled pilot tests, which he conducted himself, often acting as both experimenter and subject, but with fascinating results.Briefly, Erik suggests that human navigation ability is based on three components, a directional sense, a cognitive map, and a dead-reckoning system. The directional sense, he believes, is something of which we are unaware, but which may be based on a natural magnetic reference, as has been shown to exist in other animals. His concept of the cognitive map is a kind of mental head-up display. As he puts it, the picture we have in our mind has to correspond as closely as possible to what we do see when the real world comes into view. His dead-reckoning system is akin to an inertial system that can be updated and realigned whenever the cognitive map is adjusted to correspond with known landmarks.Erik's method has been to collect all the stories and anecdotes he could find concerning human wayfinding, to add these to his personal experiences, and then to seek to explain them in terms of his hypotheses. Many of his most instructive examples are cases where the human navigational sense has gone spectacularly awry, the most extreme being a German tutor whose sense of direction was reversed everywhere except for a few small areas in the vicinity of his home. Outside these areas, his disorientation was such that he saw the sun apparently rising in the west and setting in the east. Of particular interest to Journal readers, he describes a disorienting experience of his own when attending...
on the type of craft and the prevailing conditions, but that being adequately prepared and having the right resolve will considerably improve the chances ' of coming off best'. This masterly compilation of expertise by Peter Bruce has produced a classic which adds so much to our understanding of the dangers of storm conditions. It will remain the standard on the subject of handling small craft in heavy weather and is recommended reading for any yachtsman intending to put to sea for more than a day's sail.
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