Three minutes or more?
As we covered in our blog, What is a safety stop in diving?, at the end of each dive you should look to complete a three minute safety stop, at around five metres (16 feet).
This is not mandatory, and there are circumstances in which you should decide not to complete one (see Can I ignore my safety stop when diving?), but it is something that you should always plan to do.
It should be normal procedure whenever you are scuba diving, particularly if your dive has been deeper than 12m (40ft).
Occasionally we encounter scuba divers who return to the safety stop depth and reveal that their computer is not indicating a 3 minute stop, but longer, sometimes much longer.
We have encountered divers with ‘safety stops’ of 10 minutes or more.
Some scuba divers make something of a habit of this. We know a buddy pair who will regularly be hanging around for minutes on end after everyone else has exited the water and are sitting around waiting for them top side.
So why does this happen? What does it mean if you have to complete an extended safety stop?
More over, does it matter?
Is it acceptable or is it something that recreational sport divers should be discouraged from doing?
Why would this happen?
Quite simply, if you reach your safety stop depth and your computer is signalling more than the recommended three minutes, then you will have breached either your no decompression limit, or your maximum ascent rate, during the dive.
Essentially your computer is penalising you for that breach by adding time to your safety stop.
The safety stop is there to give your body a buffer when it comes to off loading the nitrogen that you have absorbed whilst diving. Five metres is seen as being (broadly) the optimum depth, as it provides for maximum off gassing, without surfacing.
[Note: on gassing - absorbing nitrogen as you descend/stay at depth | off gassing - releasing that nitrogen as you ascend]
When you breach your no decompression limit or your assent rate, your computer recalculates your required buffer (although it is debatable if a safety stop of longer than 3 minutes remains a 'buffer or has become a mandatory decompression stop).
It is likely that your computer will have also have given you a ‘ceiling’ during the offending dive, i.e. a minimum depth above which you must not venture, until given the all clear. Effectively a decompression stop.
You will then find your recommended safety stop has been extended to account for your dive profile.
Is it acceptable to extend my safety stop in scuba diving?
This is where things get contentious. Really contentious!
We ran three separate polls asking this very question and the result was split 52/48 against. Whilst hardly authoritative, this does mirror discussions that we have had with various groups over the past few years - the scuba diving community is divided on the subject.
Put simply, some scuba divers say there is no issue with extended safety stops and it is a personal choice, some say there is a problem and it is selfish and unsafe.
So who’s right? Time to get contentious!
The official answer has to be no, it is not acceptable. As a recreational sport diver you should stay well within no decompression limits and observe your maximum ascent rate. End of.
In addition, and as mentioned, anything longer than a three minute stop is, arguably, a decompression stop, not something that recreational sport divers are trained to manage.
But on the other side of the coin, divers who are happy to complete extended safety stops point out that they are well aware of their situation, understand what their computer is telling them, and are not completing complex, staged decompression stops, associated with technical diving.
So again, who’s right?
Do you get the impression that we might be sitting on the fence on this one?
Dive Bunnies Policy
Our official policy and view is that it is not acceptable for scuba divers to regularly or routinely incur extended safety stops.
As recreational sports divers, we are trained to proceed directly to the surface, if a problem arises.
Minor issues and difficulties can, naturally, be dealt with beneath the surface (provided everyone is comfortable to do so), but if a major problem arises, we simply surface and deal with it there.
Technical divers choose not to have that luxury.
They are trained to deal with just about every problem below the waves. This means they have the skill set, the equipment, the mindset and the preparation to do so.
Recreational sport divers do not, and this, really, is our key issue, particularly if you are diving as a group.
Within the recreational diving world the plan in any emergency will be to surface immediately, and contact emergency medical support (EMS) if necessary. If you are diving as a group, anyone in that group who may need help, will receive that help, according to the plan.
That is how the dive guides will have set up the logistics: surface, provide first aid & activate EMS if needed.
We have seen a situation where an individual had to wait onboard the RIB for an additional 9 minutes, on oxygen, whilst we waited for two divers who had accrued additional ‘safety stop’ time.
Given that a true safety stop is not mandatory, this is a situation where all other divers did not complete their stops, so the actual delay was around 12 minutes.
12 minutes in which a scuba diver in need of medical attention had to wait. It was a very long 12 minutes.
Another aspect to consider is dive centre logistics. Scuba diving operations don't have an exhaustive supply of boats and dive guides - they have a timetable that they have to operate to and, indeed, their customers expect them to operate to.
Still on gassing
Another consideration is that when you are on your safety stop, some of your body tissue will almost certainly still be taking up nitrogen.
We don’t want to get into decompression theory here, but the slowest tissue compartments within any decompression model will probably not have reached saturation at a 5m (16ft) depth by the end of your dive. Hanging around at 5m, for an extended period, will mean that those tissues are continuing to absorb nitrogen.
As these will be the ‘slowest’ compartments, any additional loading will have an impact on your NDL for any follow on dive.
Is it ever OK to end up with a longer safety stop?
Yes. There are occasions when you may incur additional time on your safety stop and, provided this is very occasional, not deliberate and unavoidable, then it is acceptable.
We have had such a situation.
On route back from a deep dive to a wreck, two of us were caught in an up swelling that resulted in us both exceeding our maximum ascent rate (this happened at a depth of between 30m and 20m (100 - 65 feet)).
We dumped air, adjusted and resolved the immediate issue, before continuing towards our eventual exit.
When we reached safety stop depth, one of us had a 4 minute obligation and the other 5 minutes, which we duly completed.
The situation was a one off, we had not deliberately exceeded our limits, the cause was beyond our control and we were over sand where it is difficult to judge depth. It was, therefore, unavoidable but crucially - it was unintentional.
Not ideal, but also a scuba diving ‘incident’ rather than a deliberate breach of safe diving guidelines.
Could an extended safety stop affect my insurance?
Scuba diving insurance will cover you for most eventualities, including forgiving minor indiscretions regarding depth, etc.
However, if you need to make a claim, your insurance may well ask for access to your computer and diving log - indeed, most insurance companies will require this in order to assess any claim.
If your dive history shows that you routinely dive at, or over, established limits, they may decide that you are not observing safe diving guidance and protocols and use this as a reason to deny your claim.
The terminology changes from policy to policy but the wording used is usually along the lines of each diver must “take all precautions to prevent anything happening which may give rise to a claim”.
Arguably, regularly breaching your no decompression limits would fall foul of taking "all precautions"
In addition, as we covered in our blog "No depth limit on my insurance...wohoo", most policies also include wording around the diver following the guidelines of their certifying agency.
So, what if I do want to dive longer?
Quite simply, this is why technical scuba diving developed.
Technical scuba diving will give you the skills and knowledge that you need to dive longer (and deeper if you so choose).
A central thrust of scuba diving certification is concerned with divers understanding that they must always dive within the limits of their training. So diving in such a way that results in stops that are longer than 3 minutes at 5m (16 feet) is not only possible, it is something that can be done perfectly safely - with the correct training.
As we covered above, the planning around these dives will also reflect and account for the altered logistics of such dives, including changes to the emergency plan.
So if we are coming off the fence on this one... Our view is a firm no, it is not acceptable to regularly incur additional safety stop time.