DOCSLIB.ORG

E:\2 ACTUAL ADOBE CONV\Act Wpd\A REGULAR

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
E:\2 ACTUAL ADOBE CONV\Act Wpd\A REGULAR NAUTICAL CHART MANUAL - VOLUME 1 - POLICIES AND PROCEDURES Seventh (1992) Edition CHAPTER 4 - HYDROGRAPHY U.S. Department of Commerce Office of Coast Survey UNITED STATES DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration NATIONAL OCEAN SERVICE Office of Coast Survey Silver Spring, Maryland 20910-3282 SEPTEMBER 22, 2000 MEMORANDUM FOR: All Cartographers Marine Chart Division FROM: Fannie B. Powers Chief, Quality Assurance, Plans and Standards Branch SUBJECT: Chapter 4 Effective immediately, the attachment replaces Chapter 4 in the Nautical Chart Manual, Volume 1, Part 1, Seventh (1992) Edition in its entirety. Chapter 4 is revised as follows: 1. Outdated procedures are deleted. 2. Acronyms are revised. 3. Pages are renumbered. 4. The ENC Object, Dredged Area, is updated a follows: A. Correctly identifies those shoaling areas (within a dredged area) which contain soundings and depth contours as depth areas. B. Explains which MCD channels should actually be collected as Fairways. C. Includes a Table of Contents and an Example Index. D. Changes the page numbering system of the Dredged Area NOS/ENC Objet Specifications. 5. Cartographic Orders and Memorandums are embedded in the text. The following Cartographic Orders were not previously distributed, but are now embedded in Chapter 4. A. Cartographic Order 026/00, filed in Section 4.4: Subject: (1) Updating of Nautical Chart Manual Information on Depth Curves; (2) Nautical Chart Manual Incorporation of ENC Objects: Depth Contour and Depth Area; (3) Depth Area NOS/ENC Object Specifications Pages The Nautical Chart Manual, Volume 1, Part 1, Seventh (1992) Edition, pages 4-41 to 4-61 are revised and the ENC Object Specifications’ section pages 4-i, 4-ii and 4-DA1 to 4-DA94 are added to Chapter 4. Updated information on depth curves and depth contours is added to the Nautical Chart Manual. Information is embedded about the ENC objects Depth Contour and Depth Area. Chapter 4 includes the corresponding NOS/ENC Object Specifications pages for the Depth Area ENC object. The NOS/ENC Object Specifications pages for the Depth Contour ENC object will be provided as an attachment in a separate cartographic order. Please note the new name and numbering system of the specifications (ENC), “ENC Extraction Specification” is now entitled “NOS/ENC Object Specifications”. The new numbering system will now incorporate two (2) lettrs from each ENC object name. B. Cartographic Order 031/00, filed in Section 4.2.4: Subject: Danger to Navigation Reports NOS field units (vessels, contractors and navigation response teams) are required to submit a Danger to Navigation Report upon discovery of any of a variety of dangers listed in Section 4.2.4. Historically, these dangers have been reported directly from the field unit to the U.S. Coast Guard (USCG) and the National Imagery and Mapping Agency (NIMA) for inclusion in the Notice to Mariners (NM). This policy has changed and Danger to Navigation Reports shall now be processed according to the procedure detailed in Section 4.2.4. Danger to Navigation Reports shall be evaluated for chart application in the Marine Chart Division. MCD shall submit information evaluated and applied from the Danger to Navigation Reports to the USCG and NIMA for inclusion in the NM. It should be noted that the attachment requires that Danger to Navigation Reports must be processed immediately and NM items generated from a Danger to Navigation Report should be submitted to USCG and NIMA within one week, at most, after receiving the document in MCD. C. Cartographic Order 032/00, filed in Section 4.13.5: Subject: Platform Sign Designations The Eighth Coast Guard District has discontinued publishing new and revised platform sign designations Effectively immediately, within the area of the Eighth Coast Guard District’s jurisdiction, sign designations shall be removed from charts going forward for printing. The positions of platforms and other oil/gas structures will continue to be charted and updated. Sign designations shall be charted for platforms that fall within the areas of all other Coast Guard Districts. NAUTICAL CHART MANUAL 4 HYDROGRAPHY 4.1 General Natural hydrographic features are charted after a thorough study of the configuration of the bottom as portrayed by surveys, primarily NOS hydrographic surveys. Submarine relief must be presented clearly, and important objects must not be obscured by other data. A dangerous rock, an islet, or the least depth over a shoal must be shown prominently; small islets and rocks should be exaggerated, if necessary, to make them easily discernible. The graphic portrayal of hydrographic information on a chart is represented by depth soundings, their associated depth contours or curves, depth-dependent color designations (blue tints), and notes showing the controlling depth of improved channels. Together these must convey adequate depth information to enable the chart user to navigate safely. Labels describing the character of the bottom are particularly important in harbors and other anchorage areas, but are also useful to fishermen. Symbols and labels depicting the existence of such natural dangers as ledges and reefs and isolated rocks, as well as man-made obstructions ranging from fish havens to cribs and platforms to submarine cables and pipelines, are also charted. Guidelines published in the Hydrographic Manual, Fourth Edition, 1976, and Wire-Drag Manual, Publication 20-1, are designed to ensure that basic NOS hydrographic surveys (as defined in Section 4.2.1) supersede all previous NOS surveys in the area covered. The proper charting instructions must be clearly stated, and exceptions shall be noted in the Descriptive Report (DR), for the application or removal from charts of wrecks, dangers, least depths, or wire-drag clearances, etc. Data handling throughout the system must be prompt and thorough to ensure timely dissemination of information to chart users. Questionable recommendations for charting action must be referred for resolution to HSD through the Chief, NDB. When applying hydrography, the cartographers must constantly be alert for items that should be included in the NM. This is most important since failure to recognize a potential navigational hazard and to alert mariners via the NM could result in a major marine disaster. Additionally, early requests for supplemental information to facilitate the processing of these items is critical. NDB shall be notified immediately of any requirement for data to rectify discrepancies and deficiencies which may preclude safe disposition of critical items or eventual assimilation of the source into the data base. Items requiring immediate attention for charting action or publication in the NM should be applied and a NM issued pending such resolution. The mariner must always be informed of any dangers suspected, whereas final corrective action can be taken later. A questionable feature is usually charted as "Rep" (reported) until it has been resolved. When applying reviewed basic surveys to the charts, the cartographer must also take care not to inadvertently remove items dating from sources more recent than the survey. Conflicts between REVISED AUGUST 25, 2000 Section 4.1 NAUTICAL CHART MANUAL contemporary hydrographic and topographic surveys in the delineation of the low water line, or the height rocks awash actually uncover, should be resolved by giving greater weight to the information on the reviewed hydrographic survey. More care is required in evaluating unreviewed hydrographic surveys because of the development of increasingly sophisticated photogrammetric methods (e.g., infrared photography and photobathymetry) to record these hydrographic details. Hydrography shall be applied from the largest- to the smallest-scale charts, with the larger-scale portrayal serving as the source for the next-smaller scale. Detail is eliminated and generalized as scale is reduced. Yet critical shoal soundings, rocks, and other dangers must be retained when applying surveys through the scales. Significant submerged features should not be generalized, and generalization must never compromise navigational safety. To aid in navigating by echo-sounding apparatus, depth curves are given special prominence on nautical charts in areas where modern hydrographic surveys have been made. The more accurately the chart depicts deepwater submarine relief, the more certain the navigator can be of the vessel's position. Note that hydrographic features are always labeled using slant (italic) type whereas topographic features are labeled with vertical type. 4.2 Hydrographic Surveys The principal objective of hydrographic surveys conducted by NOS, with few exceptions, is to obtain basic data for the compilation of nautical charts. Emphasis is on those features that may affect safe navigation. The accuracy and adequacy of a nautical chart depend on the quality of the hydrographic surveys from which it is compiled and the skill of the cartographer in applying this information. Generally, only basic surveys and field examinations are assigned "H" or "FE" registry numbers and are archived. However, upon occasion, special-purpose hydrographic, reconnaissance, or evaluation/test surveys are assigned a "D" registry number in conformance with requirements set forth in the project instructions developed for that survey. A "D"-numbered survey may be assigned a Chart Letter or Blueprint designation for storage and retrieval. The Office of Marine and Aviation Operations (OMAO) is responsible for the management
Load more

Recommended publications
  • Depth Measuring Techniques
    EM 1110-2-1003 1 Jan 02 Chapter 9 Single Beam Acoustic Depth Measurement Techniques 9-1. General Scope and Applications Single beam acoustic depth sounding is by far the most widely used depth measurement technique in USACE for surveying river and harbor navigation projects. Acoustic depth sounding was first used in the Corps back in the 1930s but did not replace reliance on lead line depth measurement until the 1950s or 1960s. A variety of acoustic depth systems are used throughout the Corps, depending on project conditions and depths. These include single beam transducer systems, multiple transducer channel sweep systems, and multibeam sweep systems. Although multibeam systems are increasingly being used for surveys of deep-draft projects, single beam systems are still used by the vast majority of districts. This chapter covers the principles of acoustic depth measurement for traditional vertically mounted, single beam systems. Many of these principles are also applicable to multiple transducer sweep systems and multibeam systems. This chapter especially focuses on the critical calibrations required to maintain quality control in single beam echo sounding equipment. These criteria are summarized in Table 9-6 at the end of this chapter. 9-2. Principles of Acoustic Depth Measurement Reference water surface Transducer Outgoing signal VVeeloclocityty Transmitted and returned acoustic pulse Time Velocity X Time Draft d M e a s ure 2d depth is function of: Indexndex D • pulse travel time (t) • pulse velocity in water (v) D = 1/2 * v * t Reflected signal Figure 9-1. Acoustic depth measurement 9-1 EM 1110-2-1003 1 Jan 02 a.
    [Show full text]
  • Hydrographic Surveys Specifications and Deliverables
    HYDROGRAPHIC SURVEYS SPECIFICATIONS AND DELIVERABLES March 2019 U.S. Department of Commerce National Oceanic and Atmospheric Administration National Ocean Service Contents 1 Introduction ......................................................................................................................................1 1.1 Change Management ............................................................................................................................................. 2 1.2 Changes from April 2018 ...................................................................................................................................... 2 1.3 Definitions ............................................................................................................................................................... 4 1.3.1 Hydrographer ................................................................................................................................................. 4 1.3.2 Navigable Area Survey .................................................................................................................................. 4 1.4 Pre-Survey Assessment ......................................................................................................................................... 5 1.5 Environmental Compliance .................................................................................................................................. 5 1.6 Dangers to Navigation ..........................................................................................................................................
    [Show full text]
  • So, How Deep Is the Mariana Trench?
    Marine Geodesy, 37:1–13, 2014 Copyright © Taylor & Francis Group, LLC ISSN: 0149-0419 print / 1521-060X online DOI: 10.1080/01490419.2013.837849 So, How Deep Is the Mariana Trench? JAMES V. GARDNER, ANDREW A. ARMSTRONG, BRIAN R. CALDER, AND JONATHAN BEAUDOIN Center for Coastal & Ocean Mapping-Joint Hydrographic Center, Chase Ocean Engineering Laboratory, University of New Hampshire, Durham, New Hampshire, USA HMS Challenger made the first sounding of Challenger Deep in 1875 of 8184 m. Many have since claimed depths deeper than Challenger’s 8184 m, but few have provided details of how the determination was made. In 2010, the Mariana Trench was mapped with a Kongsberg Maritime EM122 multibeam echosounder and recorded the deepest sounding of 10,984 ± 25 m (95%) at 11.329903◦N/142.199305◦E. The depth was determined with an update of the HGM uncertainty model combined with the Lomb- Scargle periodogram technique and a modal estimate of depth. Position uncertainty was determined from multiple DGPS receivers and a POS/MV motion sensor. Keywords multibeam bathymetry, Challenger Deep, Mariana Trench Introduction The quest to determine the deepest depth of Earth’s oceans has been ongoing since 1521 when Ferdinand Magellan made the first attempt with a few hundred meters of sounding line (Theberge 2008). Although the area Magellan measured is much deeper than a few hundred meters, Magellan concluded that the lack of feeling the bottom with the sounding line was evidence that he had located the deepest depth of the ocean. Three and a half centuries later, HMS Challenger sounded the Mariana Trench in an area that they initially called Swire Deep and determined on March 23, 1875, that the deepest depth was 8184 m (Murray 1895).
    [Show full text]
  • TECHNICAL DEVELOPMENTS in DEPTH MEASUREMENT TECHNIQUES and POSITION DETERMINATION from 1960 to 1980 by Dave Wells and Steve Grant
    “Charting the Secret World of the Ocean Floor : The GEBCO Project 1903-2003” 1 TECHNICAL DEVELOPMENTS IN DEPTH MEASUREMENT TECHNIQUES AND POSITION DETERMINATION FROM 1960 TO 1980 By Dave Wells and Steve Grant EXECUTIVE SUMMARY In this paper we describe the evolution during these two decades from simple single-beam echosounders using horizontal sextant fixing (near shore), and celestial sextant positioning interpolated by dead reckoning (offshore) to (a) (For depth measurement techniques) sidescan sonar, digital echosounders, the first (classified) SASS and Seabeam multibeam systems, and early satellite altimetry, and (b) (For positioning determination) a plethora of short and long range radio positioning systems, the Transit satellite positioning system, the early designs for GPS, long and short baseline acoustic systems, and (c) How these developments have since impacted the data available to GEBCO BIOGRAPHIES Dave Wells and Steve Grant worked together at the Bedford Institute of Oceanography for several years during the 1970s on some of the developments discussed in this paper, as part of the Canadian Hydrographic Service Navigation Group headed by Mike Eaton. Steve “retired” in 1996 but still works on a variety of hydrographic consulting and teaching projects. Dave “retired” in 1980 and again in 1998, but still teaches at three universities. INTRODUCTION During the period from 1960 to 1980, many remarkable advances were made in the technologies applicable to depth measurement and positioning at sea. Some of the initial technological developments dating from those two decades remain the basis for the most modern and effective bathymetric and positioning systems in use today. Others reached productive fruition earlier, and have since been supplanted.
    [Show full text]
  • SETTING COURSE a History of Marine Navigation in Canada Sharon A
    TRANSFORMATION SERIES 14 COLLECTION TRANSFORMATION SETTING COURSE A History of Marine Navigation in Canada Sharon A. Babaian Transformation Series Collection Transformation “Transformation”, an occasional series of scholarly La collection Transformation, publication en série papers published by the Collection and Research paraissant irrégulièrement de la Division de la collec- Division of the Canada Science and Technology Museum, tion et de la recherche du Musée des sciences et de la is intended to make current research available as technologie du Canada, a pour but de faire connaître, quickly and inexpensively as possible. The series le plus vite possible et au moindre coût, les recherches presents original research on science and technology en cours dans certains secteurs. Elle prend la forme history and issues in Canada through refereed mono- de monographies ou de recueils de courtes études graphs or collections of shorter studies, consistent with acceptés par un comité d’experts et s’alignant sur le the corporate framework, “The Transformation thème central de la Société, « La transformation du of Canada,” and curatorial subject priorities in agri- Canada ». Elle présente les travaux de recherche origi- culture and forestry, communications and space, naux en histoire des sciences et de la technologie au transportation, industry, physical sciences and energy. Canada et questions connexes réalisés en fonction des The Transformation series provides access to priorités du Musée, dans les secteurs de l’agriculture research undertaken by staff curators and researchers et des forêts, des communications et de l’espace, des for the development of collections, exhibitions and pro- transports, de l’industrie, des sciences physiques et grams.
    [Show full text]
  • A Sound Survey: the Technological Perception of Ocean Depth, 1850 – 1930
    Mikael Hård, Andreas Lösch, Dirk Verdicchio (ed.) (2003): Transforming Spaces. The Topological Turn in Technology Studies. (http://www.ifs.tu-darmstadt.de/gradkoll/Publikationen/transformingspaces.html) A Sound Survey: The Technological Perception of Ocean Depth, 1850 – 1930 Sabine Höhler Introduction: Data Volumes of Depth „It has often been said that studying the depths of the sea is like hovering in a balloon high above an unknown land which is hidden by clouds, for it is a peculiarity of oceanic research that direct observations of the abyss are impracticable. Instead of the complete picture which vision gives, we have to rely upon a patiently put together mosaic representation of the discoveries made from time to time by sinking instruments and appliances into the deep“1. The oceans were ‘deep’ well before the founding of the ocean sciences in the 1850s, but what lay beneath the waves out on the sea had hardly ever been tangibly experienced. Neither had approximately 60 years of scientific exploration rendered the oceans transparent, as the statement by the oceanographers John Murray and Johan Hjort from the year 1912 reveals. Oceanographic research could not rely on “direct observations”. Instead, it had to create its image of ocean depth through remote investigation. Depth-sounding instruments created the outlines of this new object of science. Since the middle of the 19th century the notion and image of ocean depth no longer existed independently from its scientific definitions, experimental studies, measurements, and charts. The single data points slowly gained in the processes of depth sounding were organized into profiles and contours which met the eye as coherent pictures by means of scaling, outlining and shading.
    [Show full text]
  • Seismological Monitoring of the World's First
    Appendix A Seismological Monitoring of the World’s First Nuclear Detonation— The Trinity Shot of 16 July 19451 Seismology played a modest role in the Trinity test, thereby establishing, at the very birth of the “atomic age,” a mutual interaction between seismology and nuclear testing that would become of increasing significance to both technologies as the century pro- gressed. Because the Trinity “gadget” was designed to be an atmospherically detonated military weapon for which principal damage effects were expected to be air blast and accompanying ground shock of intensities heretofore unexplored, extensive new effects data were needed to plan military applications. When the need for a full-scale test of the implosion design became clear by late 1944, Los Alamos scientists began to devise field experiments to measure both air blast and ground shock.Also, they wanted to esti- mate how each would scale with explosive energy release (yield), range, and height of burst within a principal target area (nominally, within about 20 km of ground zero). In March 1945, Herbert M. Houghton, an exploration geophysicist with Geophys- ical Research Corporation (GRC) and Tidewater Oil, was recruited to work with Los Alamos physicist, James Coon, to perfect earth shock instrumentation for the 100-ton TNT calibration rehearsal shot of 7 May 1945, as well as the unique multikiloton Trin- ity nuclear event planned for July. Houghton and Coon modified a dozen GRC Type SG-3 geophones to record both vertical and horizontal-radial components of strong ground motion at ranges between 0.75 and 8.2 km from both the calibration and nuclear shots, which were air bursts suspended on towers.
    [Show full text]
  • ROV Design 11 2.1 Underwater Vehicles to Rovs 11 2.2 Autonomy Plus: ‘Why the Tether?’ 13 2.3 the ROV 18
    The ROV Manual: A User Guide for Observation-Class Remotely Operated Vehicles This page intentionally left blank The ROV Manual: A User Guide for Observation-Class Remotely Operated Vehicles Robert D. Christ and Robert L. Wernli Sr AMSTERDAM BOSTON HEIDELBERG LONDON NEW YORK OXFORD PARIS SAN DIEGO• SAN• FRANCISCO • SINGAPORE• SYDNEY• TOKYO • Butterworth-Heinemann• is an• imprint of Elsevier• • Butterworth-Heinemann is an imprint of Elsevier Linacre House, Jordan Hill, Oxford OX2 8DP 30 Corporate Drive, Suite 400, Burlington, MA 01803 First edition 2007 Copyright © 2007, Robert D. Christ. Published by Elsevier Ltd. All rights reserved. The right of Robert D. Christ to be identified as the author of this work has been asserted in accordance with the Copyright, Designs and Patents Act 1988 No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means electronic, mechanical, photocopying, recording or otherwise without the prior written permission of the publisher Permissions may be sought directly from Elsevier’s Science & Technology Rights Department in Oxford, UK: phone ( 44) (0) 1865 843830; fax ( 44) (0) 1865 853333; + + email: [email protected]. Alternatively you can submit your request online by visiting the Elsevier web site at http://elsevier.com/locate/permissions, and selecting Obtaining permission to use Elsevier material Notice No responsibility is assumed by the publisher for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions or ideas contained in the material herein.
    [Show full text]
  • Bathymetric Charts 1
    14 August 2008 MAR 110 HW-2a: ex1Bathymetric Charts 1 Homework 2a Bathymetric Charts [based on the Chauffe & Jefferies (2007)] 2-1. BATHYMETRIC CHARTS Nautical charts are maps of a region of the ocean used primarily for navigation and piloting. These charts display the bathymetry or depths of the sea floor below sea level. Historically, the sea floor depths were obtained by lowering a weighted cable to the sea floor. Today, sea floor depths are obtained with a ship-mounted sonic depth recorder which bounces sound waves off the sea floor (Figure 2-1a). A sound generator on the ship emits sound waves that strike the sea floor and are reflected upward to a listening device called a hydrophone. The method is faster, more accurate and allows continuous depth determination as a ship travels. Each measurement of depth to the sea floor is called a sounding. Figure 2-1a.Acoustic Depth-Sounding. A ship’s hull-mounted “acoustic pinger” emits a sound pulse that travels to the seafloor, reflects, and then travels back to the ship’s listening devise called a hydrophone. The roundtrip travel time of the sound pulse is recorded and the depth is computed (see formula). The depth recorder operates continuously making a dense set of depth measurements along the ship’s track. 14 August 2008 MAR 110 HW-2a: ex1Bathymetric Charts 2 Shipboard computers record the round-trip travel time of the sound waves and calculate depth by multiplying the known speed of sound in water (Sw = 1460 meters/second) by half of the travel time: D =Sw x ½ travel time , where the depth of the water D in meters is the product of the sound speed in water and one half of the total travel time to the bottom and back.
    [Show full text]
  • BOAT CREW HANDBOOK – Navigation and Piloting
    BOAT CREW HANDBOOK – Navigation and Piloting Captain John A. Henriques BCH 16114.3 December 2017 John Ashcroft Henriques John Ashcroft Henriques was one of the most important Revenue Cutter Service officers of the 19th century. As founder and first superintendent of the Revenue Cutter Service School of Instruction, forerunner of the modern Coast Guard Academy, he was arguably the most important figure in educating Service officers in seamanship and navigation. Henriques began his career in March 1863. The next three years proved hectic ones, beginning with a tour on the James C. Dobbin, a sailing cutter that played a part in his later career and brief assignments as a junior officer on board cutters Crawford, Northerner and John Sherman. In less than five years, Henriques received promotions from third lieutenant to the rank of captain. This rapid rise testified to Henriques’ seafaring experience and command presence. Shortly after the Civil War, a journalist commented, “Captain Henriques is thoroughly posted and every inch a sailor [journalist’s italics] and a gentleman, as is well known to all who have made his acquaintance.” Captain Henriques saw a lot of sea time in the Atlantic, Pacific, rounding Cape Horn, and in Alaskan waters. In the decade following the War, he commanded four ocean-going cutters, including the Reliance. As captain of Reliance, he sailed from the East Coast around hazardous Cape Horn to San Francisco. The voyage began August 1867 and included eight brutal days of gale-force winds and heavy seas while the 110-foot topsail schooner slugged her way around “the Horn.” A few months after Reliance arrived in San Francisco, Henriques sailed for Alaska, becoming one of the first cutter captains to serve in the treacherous waters of that territory, and the first one to enforce U.S.
    [Show full text]
  • Canadian Hydrographic Service
    CANADIAN SPECIAL PUBLICATION OF FISHERIES AND AQUATIC SCIENCES 67 Proceedings Centennial Conference Canadian Hydrographic Service FI 1983 DFO - Library MPO - Bibliothéque 1 1 11 1 11 11101,18 ,110 11111 1 OTTAWA APRIL 5-8 AVRIL. 1983 Comptes rendus Conférence du Centenaire Service hydrographique du Canada 1983 PUBLICATION SPECIALE CANADIENNE DES SCIENCES HALIEUTIQUES ET AQUATIQUES 67 a " CANADIAN SPECIAL PUBLICATION OF FISHERIES AND AQUATIC SCIENCES 67 Centennial Conference of the Canadian Hydrographic Service "FROM LEADLINE TO LASER" April 5-8, 1983 Government Conference Centre LIBRARY Ottawa, Canada FISHERIES AND OCEANS 1 Q1U Sponsors 13IIILIOT ET OCÉANS, Canadian Hydrographic Service pîoiES Canadian Hydrographers Association Conférence du Centenaire du Service hydrographique du Canada "DE LA LIGNE DE SONDE AU LASER" 5-8 avril, 1983 Centre de Conférences du Gouvernement Ottawa, Canada Responsables Service hydrographique du Canada Association des hydrographes canadiens PUBLICATION SPÉCIALE CANADIENNE DES SCIENCES HALIEUTIQUES ET AQUATIQUES 67 Minister of Supply and 'Services >Canada 1983 © Ministre des Approvisionnements et Services Canada 1983 Availàble En vente par la poste: Canadian Government Publishing Centre Centre d'édition du gouvernement du Canada . Supply and Service's Canada Approvisionnements et Services Canada 'Ottàwà, Ont. K I A 059 Ottawa (Ontario) Canada KIA 0S9 or through your bookselier ou chez votre libraire or from ou au Hydrographie Chart Distribution Office Department of Fisheries and Oceans Bureau de distribution des cartes marines P.O. Box 8080, 1675 Russell Rd. Ministère des Pêches et des Océans Ottawa, Ont. C.P. 8080, 1675, chemin Russell Canada K I G 31-16 Ottawa (Ontario) Canada K1G 3H6 Catalogue No. Fs 41-31/67 ISBN 0-660-52374-4 N° de catalogue Fs 41-31/67 ISSN 0706-6481 ISBN 0-660-52374-4 Ottawa, 1983 ISSN 0706-6481 Ottawa, 1983 Canada: $12.00 Other countries: $14.40 Canada : 12 $ Autres pays : 14.40$ Price subject to change without notice.
    [Show full text]
  • Bathymetric Charts 1
    5 September 2018 MAR 110 HW-2: Bathymetric Charts 1 Homework-2 Bathymetric Charts [based on the Chauffe & Jefferies (2007)] 2-1. BATHYMETRIC CHARTS Nautical charts are maps of a region of the ocean which are used primarily for navigation and piloting. Nautical charts map bathymetry or the depth of the sea floor below sea level. Historically, the sea floor depths were obtained by lowering a weighted cable to the sea floor - hopefully- and measuring the length of the line/rope. In the deep ocean, this method was inaccurate. Today, sea floor depths are obtained with a shipboard depth recorder system. This recorder system has a ship’s hull-mounted sound generator that emits sound waves (or “pings”) every second or so. Each ping travels downward (see Figure 2-1), bounces off the sea floor and travels upward to a hull-mounted listening device called a hydrophone. The recorder computes the depth from the Figure 2-1 Acoustic Depth-Sounding. A ship’s hull-mounted “acoustic pinger” emits a series of sound pulses; each of which round-trip travel time of the ping travels to the seafloor, reflects, and then travels back to the ship’s listening device called a hydrophone. The roundtrip travel time of or sounding. The method is much each sound pulse is recorded, and the depth is computed (see formula). The depth recorder operates continuously making a dense faster and much more accurate set of depth measurements along the ship’s track. than the historical method; and allows for continuous series depth recordings as a ship travels forward over the seafloor.
    [Show full text]