For anything to be protected by copyright, it MUST have the copyright symbol and date of copyright. The dive tables are copyright protected by Diving Science & Technology Corp., so it would be illegal for you to 1) reproduce the tables for your own profit, or 2) to give to someone so they don’t have to buy their own. However, it would not be illegal for you to reproduce the dive tables you already own for your own personal use, e.g. so you could keep an original set at home and have a set to travel with, so that in case you lose your travel set, you still have the originals.