Admiralty Guide to the Practical Use of ENCs - Edition 1 - Directions for Updating This Volume

Nov 1, 2026

Admiralty Guide to the Practical Use of ENCs provides authoritative guidance for mariners and ECDIS users on the practical application of Electronic Navigational Charts (ENCs). It covers ENC structure, cell concepts, display symbols, and the differences between traditional and simplified symbols, then explains user controls, safety settings, depth representation, and further display considerations. The guide addresses display scale choices, ENC accuracy concepts, voyage planning workflows, and step-by-step installation and updating, including validation checks and service subscription management.

LanguageEnglish

CategoryTechnology

FormatPDF

Pages174

Reading Time7 h 18 min

AccessFree to download

Introduction

What is an ENC?

User Controls for ENC Display

Further ENC Display Considerations

ENCs and Display Scale

ENC Accuracy

Voyage Planning with ENCs

Installing and Updating ENCs

Annexes

Admiralty Guide to thePractical Use of ENCs NP231Ist Edition2012ADMIRALTY NP231 ADMIRALTY REFERENCE PUBLICATIONSEDITION I 2012 ADMIRALTY GUIDE TO THEPRACTICAL USE OF ENCs | IMPORTANT-SEE RELATED ADMIRALTY PUBLICATIONS
Notices to Mariners(Annual.Permanent,Preliminary and Temporary);NP5OII (Symbols and Abbreviations):NP5012 (The Admiralty Guide
to ENC Symbols Used in ECDIS);The Mariner's Handbook(especially Chapters I&2 on the use,accuracy and limitations of charts);
Sailing Directions(Pilots);List of Lights and Fog Signals;List of Radio Signals;Tide Tables (or their digital equivalents).
KEEP CHARTS AND PUBLICATIONS UP TO DATE AND USE THE LARGEST SCALE CHART APPROPRIATE | | --- | PUBLISHED BY THE UNITED KINGDOMHYDROGRAPHIC OFFICE ◎ Crown Copyright 2012 DIRECTIONS FOR UPDATING THIS VOLUME Subsequent amendments to this book will be included in Section Vllof the Weekly Edition of AdmiraltyNotices to Mariners,copies of which can be obtained from authorised Admiralty Distributors,or from theUKHO Website www.ukho.gov.uk/msi A cumulative list of amendments is published quarterly in Section Vil and provides a summary List of theentries in the current editions which have been amended.New or extensively altered material is intendedto be pasted over the existing material.Shorter amendments should be made in manuscript.The WeeklyEdition number is shown on all amendments.The appropriate indexes and diagrams should also be amendedif necessary. RECORD OF AMENDMENTS This Volume should only be used once fully updated by Section VII Notices to Mariners.The inclusion ofamendments in this Volume should be recorded in the following table: NEW EDITION First Amendments Weekly Notices to Mariners(Section VII) 2oly 26/42.73期 CONTENTS Introduction Hydrographic Notes……………………………………………………………………………………………………………………………………vii Reference Publications………………………………………………………………………………………………………………………………vii 1 What is an ENC? I.I ENC format…………………………………………………………………………………………………………………………………………………1 1.2 ENC status…………………………………………………………………………………………………………………………………………………1 1.3 ENC content………………………………………………………………………………………………………………………………………………2 1.4 ENC structure……………………………………………………………………………………………………………………………………………3 1.5 ENC cells……………………………………………………………………………………………………………………………………………………6 1.6 ENC display symbols…………………………………………………………………………………………………………………………12 1.7 Traditional and Simplified symbols……………………………………………………………………………………………14 1.8 New symbols………………………………………………………………………………………………………………………………………17 1.9 New ECDIS derived symbols………………………………………………………………………………………………………24 1.10 Pick Reports- Interrogating ENC data………………………………………………………………………………………31 2 User Controls for ENC Display 2.1 Introduction ………………………………………………………………………………………………………………………………………35 2.2 ECDIS display modes…………………………………………………………………………………………………………………………36 2.3 Colour Palettes-day and night use of ECDIS……………………………………………………………………38 2.4 Safety settings in ECDIS display…………………………………………………………………………………………………41 2.5 Display of depth shades…………………………………………………………………………………………………………………44 2.6 Shallow pattern……………………………………………………………………………………………………………………………………45 2.7 The Isolated Danger symbol…………………………………………………………………………………………………………46 3 Further ENC Display Considerations 3.1 Introduction ……………………………………………………………………………………………………………………………………52 3.2 ENC content and format considerations………………………………………………………………………………52 3.3 ECDIS software considerations…………………………………………………………………………………………………59 4 ENCs and Display Scale 4.1 ENC compilation scates………………………………………………………………………………………………………………66 4.2 Selecting appropriate display scales………………………………………………………………………………………66 4.3 Zooming in to a larger scale………………………………………………………………………………………………………67 4.4 Zooming out to a smaller scale................ …………………………………………………………71 4.5 Display variability due to scale …………………………………………………………………………………………………74 5 ENC Accuracy 5.1 ECDIS and prudent navi

FAQs

What does the guide require for keeping ENCs usable over time?

It directs users to keep charts and related Admiralty publications up to date and to record amendments using the provided amendment record table. It also states the volume should only be used after full updating via Section VII Notices to Mariners.

How does the guide describe controlling ENC display in ECDIS?

It explains user controls including ECDIS display modes, color palettes for day/night use, safety settings, depth shading display, and handling features such as the Isolated Danger symbol.

What topics are covered regarding accuracy and safe navigation?

It covers ECDIS and prudent navigation, the components of accuracy, survey accuracy, unreliable depths, and the role of vertical and horizontal datums in ENC accuracy.

Nov 1, 2026

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