Today I found myself surfing around the web and ran into a blog post on another instructors blog and I was instantly brought back in time to a little over a year ago when I encountered two recreational divers sharing air on a safety stop at the LSD-32 Spiegel Grove in Key Largo FL. One diver was completely out of air and the other one (who is sharing with his buddy) had less then 300 psi in his tank, both breathing extremely heavily. The two divers had just started started the safety stop and clearly did not have enough breathing gas for them to complete the stop. I supplied both of them with gas and completed the dive with them, back on the boat when questioned about why they had not returned to the surface they stated “We had to finish our safety stop.”
My training emphasized that a safety stop is always part of the dive, so really all recreational dives are all decompression dives with a minimum 3 minute deco stop at 15 feet. How is a safety stop difference from a deco stop? They are both doing the same thing…. – Rob, http://www.thumbthedive.com/2007/09/27/safety-stop/
Sadly this was not the only time I encountered people in distress, who as a result of not understanding why we do a safety stop put themselves at even great risk. Worst of all is I see instructors who also don’t understand the purpose. How can we expect an instructor to teach a student about information they themselves do not properly understand. When you combine this failure of proper education in the classroom with instructors providing bad information on the internet (such as the quote displayed to the left) its no wonder that new divers get the wrong idea about what a safety stop is. Some people would immediately use this example to once again make the statement of instructors from certain agencies are bad instructors. The simple fact is that every agency has bad instructors, those agencies with more instructors are going to have more bad instructors its simply a matter of percentages, no one agency is worse then the other when it comes to bad instructors. The simple fact of the matter is, this is a failure of individual instructors who take what their instructors tell them as gospel. When talking on this exact topic I once had a new instructor tell me: “My course director told me safety stops are mandatory, so there is no way you can skip one. I don’t care what you say.” This demonstrates not that the educational system is flawed but that many new instructors view instructor trainers as infallible, and fail to think for themselves.
So this leads to the question of what exactly is a “Safety Stop”. A Safety Stop is a precaution against any unnoticed dive computer malfunction, diver error or physiological predisposition to decompression sickness. They where introduced in diving a result of divers inadvertantly making ascents to the surface that where to rapid to allow for the body to properly off gas, and as a result the safety stop provided more time for off-gassing to occur at a depth where the most rapid off gassing of nitrogen occurs.
Safety Stops are performed at a depth range of 10′ – 20′ for a time period of 1 – 5 minutes. Most training agencies provide divers with the general rule of a mandatory stop at 15′ for 3 minutes for any dive deeper then 60′ and a recommended safety stop being performed at the conclusion of every dive. This information is based on using an ascent rate of 45fpm – 60fpm. Note that safety stops have a depth range of 10′ – 20′, I continue to get a kick out of ascending from a deep dive to find divers stacked on top of each other right at the 15′ mark.
When you complete any stop with the intention of off gassing its important to consider your position in the water. Completing a stop in a vertical position will result in gas rising to the highest point in the body, in most cases your head. The proper position for completing any off gas stop and for that matter your entire ascent is in a horizontal position. This allows your entire body to off-gas at an equal rate.
Its very important to remember Safety Stops unlike Decompression Stops are not mandatory, and should never be done in emergency situations such as an injured diver or an out of air situation.
General Rules For Safety Stops
- Safety stops are optional and should only be completed when you can safely do so.
- Safety stops should be completed at a depth between 10′ – 20′ for a period of 3 minutes or more.
- It should take a full minute to get from your final stop depth to the surface. AKA your ascent rate from your safety stop to the surface should be no greater then 15fpm.
- Safety Stops should be completed in a horizontal position, not vertical. This allows your entire body to off gas equally.
- Should you complete your safety stop before your buddy(ies), remain with your team until all members are ready to surface. More dive accidents occur on the surface or in less then 20′ of water then any where else.
- Discuss Safety Stop procedures with your buddy as part of the pre-dive plan, this ensures that everyone is on the same page.
I often get questions from divers about my personal feelings on safety stops. The simple fact is in most cases when I am not diving with students I don’t do them at all. A safety stop is designed to slow the ascent to allow for additional off gassing. This is achieved through what technical divers refer to as a minimum decompression ascent. Ascents performed using this method are done by ascending 10′ over the course of 30 seconds followed by a 30 second hold at the given depth. This method of ascent results in an overall ascent rate of 10fpm. In addition to this on any dive deeper then 60′ I carry a decompression bottle with 50% oxygen in it, on no decompression dives this bottle is used to acceleration the off gassing process. Switching to this gas results in an additional gas switch stop being done at 70′. Its important to note that using high concentrations of oxygen for accelerated off gas should not be done with out proper training and certification. All and all for a 100′ dive this means my total ascent time to the surface is around 11 minutes where a recreational diver following the standard 60fpm and 3 minute safety stop has an ascent time of around four and a half minutes.
The first objection to my ascent method that I hear is always the same. “God you spend 11 minutes coming up from 100′, that has got to be boring.” In fact its not and in many cases I see just as many cool things during that 10 minute period as I do during the portion of the dive where I am on the bottom. I huge range of marine life lives in the water column not on the bottom of the oceans. Sharks, squid, dolphin and lots of fish spend their entire life living in the water column. The ascent itself is a great time to see them.
How do you go about ascending from your dive and what cool experiences have you had during your ascents from the depths of the ocean?
