Wreck Diving Limits - Are You Diving to the Limits ?

When we talk about penetrating a wreck we, as divers, are always interested in the light we will have inside. Some of the light comes from the surface in the form of ambient (sun) light, while we provide other light from the dive lights we carry. Remember you should always carry one primary and at least 1, of possible 2 back up lights. The more backup lights the better.

During this blog we will talk about the limits established for diving in overhead environments. Here we are talking about a wreck, but it could, and does cross over to diving in a cave. In the near future I will have on my talkshoe show # 20348, Ron Carmichael who is an expert in training divers to dive in a cave. Look for dates of that interview in an upcoming blog and talkcast.

There are at least three limits we must observe.

1. Edge of light zone
When you enter the wreck and look back you will see some light, that is the ambient light coming from the surface/ Stay within this light that is available. Meaning that you should not penetrate if you can no longer see this light. If the dive is murky, then there will be less natural light entering the wreck. This also means, of course, that you should not make a penetration dive at night.

2. Linear distances of 40 meters /130 feet
In open water per PADI guidelines, a diver should not dive deeper than 40 meters / 130 feet. This is of course the recreational safe limits. There are courses that teach divers to dive deeper, but only attempt that under a certified instructor. Similarly, your maximum distance from the surface when penetrating a wreck should not exceed this same distance. This means that the depth of the wreck and penetration distance should not exceed 130 feet.

3. One third of your air supply
Whenever you dive in an overhead environment you dive and exit the wreck with 2/3 air and this includes the time it takes to surface. Simply put it this way, 1/3 to dive and go into the wreck, 1/3 to exit and go to the surface and 1/3 reserve.

This is known as the "Rule of Thirds". Saving two thirds of your air for exiting gives you more than of the most important factor you need to handle a problem inside a wreck: time.

You do not have to surface with 1/3 air, just exit the wreck with the air. You can dive around the wreck till an appropriate time to surface as you would if in open water. If diving deep, make sure you give yourself time to do a 15 feet stop for 3 minutes, ie a safety stop.