Powell - Deco for divers: a divers guide to decompression theory and physiology

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DECO FOR

DIVERS

A Divers Guide to Decompression Theory and Physiology

MARK POWELL

AquaPress Ltd and Mark Powell 2014

The right of Mark Powell to be identified as the author of this work has been asserted in accordance with the Copyright Designs and Patents Act, 1988.

This book is sold subject to the condition that it shall not, by way of trade or otherwise, be lent, resold, hired out, or otherwise circulated without the publishers prior consent in any form of binding or cover other than that in which it is published and without a similar condition including this condition being imposed on the subsequent purchaser.

An AquaPress Book
Published by AquaPress Ltd
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United Kingdom

First Published 2008
Reprinted 2009, 2013
Second Edition 2014

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A CIP catalogue record for this book is available from the British Library.

Diving is an inherently dangerous sport. The information contained in this book is supplied merely for the convenience of the reader and should not be used as the sole source of information. This book is not a substitute for proper training by a recognized diver training agency. The author and publisher have made every effort to ensure that the information in this book is correct at the time of going to press. However, they accept no liability or responsibility whatsoever for any loss, damage, accident, injury or inconvenience sustained by any person using this book or following advice presented in it, provided that this shall not limit or exclude liability for death or personal injury caused by their negligence.

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ISBN: 978-1-905492-29-9
eISBN: 978-1-905492-36-7

FOREWORD

This is a truly remarkable book which covers all the various theories of decompression and ascents for divers in a most readable and understanding manner. The elimination of the mathematics and jargon means that any diver should easily understand the basis for the diverse decompression procedure.

The author has been able to be very objective and not select any one of these many methods used by tables and dive computers as being necessarily the best. The ability to read and compare all of these in one place allows the diver to make up his or her own mind as to which is indeed the safest. Mark Powell is to be congratulated for writing this excellent book and making decompression and ascent so understandable for any diver. He shows an excellent understanding of the many different methods with clear explanations and figures.

As a technical diver, he uses many of these methods for safe ascents himself and the clarity of his presentation is far superior to the complex books and papers in this field today. There is no other comprehensive book on decompression to my knowledge which is so easy to read and understand by the average recreational or technical diver.

Every diver can benefit from this knowledge and I certainly recommend the International Divers Alert Network and Undersea and Hyperbaric Medical Society to include this title in their book lists.

Peter B. Bennett, Ph.D., D.Sc.
Executive Director, UHMS
Emeritus Professor of Anesthesiology
Duke University Medical Center
Founder & 1st President, DAN

DECO FOR DIVERS BY MARK POWELL
HAS WON THE FOLLOWING AWARDS

Contents

A pair of divers explore a Red Sea wreck

Introduction

This book is aimed at divers who are interested in finding out a little more about the physiology and concepts underlying decompression

This book was written to provide an accessible source of information on decompression theory. It is aimed at divers who are interested in finding out a little more about the physiology and concepts of decompression. The idea initially took root when I first started trying to learn more about decompression theory in order to satisfy my own interest. There were a number of sources of introductory information giving the basics of decompression theory. Some of these are very good introductions to the subject and are well explained. However, I found that if I wanted to find out any more about any aspect of the theory there was a shortage of follow-on information. The only option was to jump into the original source articles, research papers or conference proceedings. Often the original source material was highly detailed with each paper looking in great depth into a single aspect of the individual concepts. A further hindrance was that many of these original papers were published in quite obscure journals or as research reports. Journals such as the Undersea and Hyperbaric Medicine Journal or the Aviation, Space and Environmental Medicine Journal can only be found in specific research or university libraries. Many of the papers written by decompression researchers working for the British, US and other navys were published as internal research notes and were not available in even the most comprehensive libraries. I was frustrated by this gap between the introductory texts and the source material. What I wanted was an intermediate overview that went into more detail but wasnt written for academics or researchers. Unfortunately there was no such text available.

When I became a technical diving instructor I started teaching other people about decompression theory. I tried to give an overview of decompression theory at this intermediate level to give my students a better understanding of what was happening during decompression dives. This was always very popular amongst divers who, like me, had always wanted to understand more about the concepts and models underlying decompression theory. I was always being asked if I could recommend a good book which covered this area but as before, there was no such text available. Over time I started giving out notes for the decompression theory portion of my courses and these notes started building. Initially they were just a few pages but the notes became more and more comprehensive and started to cover more and more areas. Eventually they grew into this book.

As I wrote this book I could have started almost every sentence with current thinking is or we currently believe. There are many theories as to the causes and mechanics of decompression but very few known facts.

There is a false sense of security amongst recreational divers that decompression is a well understood science and that decompression illness can easily be avoided if you stick to your decompression tables.