Have you heard of the drysuit clock? Don’t worry if not, Google doesn’t turn up much of an answer following a search either. But it’s an expression that comes up on dive sites from Bali to Mexico to the Mediterranean – and I’m sure divers talk about it in other places, too.
Whenever you dive in a place that has temperate or cold water but warm air temperatures, the challenge becomes this: you need to get ready fast enough to avoid sweating through your undergarments but slow enough to avoid making mistakes. I’ve been walking that line for the past two years, and here are some of the lessons I learned about the drysuit clock and getting ready.
Why Write About This Now?
For the past week or so, Gozo, the small island in the Mediterranean Sea I now call home, has been dealing with a 40+ degree heatwave. That’s 104 Fahrenheit for those of you who think in imperial terms. The sea continues to be around 27 degrees on the surface, and around 17 degrees below 45 metres (that’s a little over 50 Fahrenheit). So, the difference is pretty big, and with the heatwave going on for two weeks, it’s not just a one-day concern.
Plus, I have a week or so in European lakes coming up, which may even throw single-digit temperatures at me – combined with high 20s or 30s on the surface. Now, I’m actually no stranger to diving in single-digit temperatures. Six or so years of diving and teaching in Scotland trained me well, or so I thought. Turns out, nine years in Asian waters and climates change the way your body reacts even to 15-degree water.
What is the Drysuit Clock and Why Does it Matter?
Considering I haven’t found a formal definition, I’ll just describe it as the amount of time you have between getting in your drysuit and getting in the water without overheating or sweating excessively. Put simply, once you put on and zip up that suit, you’re on a clock.
What happens if you’re too slow? You get hot. Too obvious? Well, let me use medical terms. If you take too long between getting in your drysuit and cooling down, your body overheats. Overheating puts you at risk of heat exhaustion, especially if you’re working hard. Carrying tanks, anyone?
Aside from high temperatures and working hard, high humidity can also predispose you to heat exhaustion. The latter was more of a problem in Indonesia. Current temperatures in Gozo may be higher than in Bali, but at 10%, humidity is much lower.
What happens if you’re too fast? You’re more prone to making mistakes when you rush. If you haven’t heard it before, one of (technical) diving’s golden rules proclaims that “slow is smooth, and smooth is fast.” So, you’re trying to find a happy medium between being slow enough to follow your full pre-dive routine and fast enough not to overheat.
Overheating is problematic not only because of heat exhaustion. Starting a dive excessively hot can predispose you to excessive ongassing and therefore compromise your planned decompression. You’re likely to absorb more gas when you’re warm. As you get progressively colder during the dive, offgassing will become less efficient.
Speaking of heat – before overheating, you’re likely to start sweating. Profusely. To the point where your undergarments get wet and feel cold. So that’s another thing to manage. By now, you should start seeing that the drysuit clock is perhaps a little more complicated than you thought. Time to look at solutions for the drysuit clock and getting ready conundrum:
Solution 1. Dive in a Wetsuit
Depending on the water temperature and your susceptibility to cold, that may be a solution. It stopped working for me as my dives got longer. I distinctly remember one dive in 2020, on a small pinnacle in the Lombok Strait between Bali and Nusa Lembongan. Bottom temperature 18 degrees, with 23 degrees from the surface down to 10 metres. Runtime a bit more than two hours.
That may not sound too bad, but as I was deploying my SMB, the movements were no longer automatic. I had to think hard and make every movement deliberately, even though I had made them thousands of times. The fact that my body was shaking with cold didn’t help, either. I was wearing a relatively new 5mm wetsuit and a 3mm vest with a hood. That dive was when I realised that I needed a better solution.
Solution 2: Finetune Your Pre-Dive Routine
That better solution for me was a drysuit, and I’ve been diving dry 99% of the time since early 2021. Most of that time was spent in Indonesia but also Mexico and now Gozo. One of the things that has worked for me is finetuning my pre-dive routine.
What do I mean by that? First, I try to find shade at dive sites whenever possible. Second, I prepare every bit of equipment I can before even getting near undergarments and the drysuit. Third, I check with teammates to see that everyone is ready to get dressed and that all equipment is prepared before we start the drysuit clock.
Sounds easy? It is and it isn’t. The principle is super simple, but it needs adjustments every time you change location and sometimes even between dive sites in the same location. It also varies between boat dies and shore dives. I’ll get back to that below.
Solution 3: Cool Off Before You Kit Up
So, your equipment is prepared, and your drysuit is zipped up? Time to get wet, even before you don that twinset, rebreather or sidemount gear. For me, jumping in the water before completing the final kit up allows me to cool down and complete the remaining preparations more comfortably and without feeling the urge to rush into the water.
Can’t jump off the boat? Check if there is a shower. Even a little water over your head while you’re waiting to be dropped can make a big difference.
Solution 4: Choose Suitable Undergarments
So, I mentioned the sweat problem above. Sweating is part of our bodies’ cooling mechanism, but when it leaves your undergarments wet, it can cause problems later by cooling you down on the dive.
Specialist diving base layers – like skiing and mountaineering base layers – are designed to wick moisture away from your body to keep you dry. They’re worth the investment.
If you’re diving dry in relatively warm waters, you may be tempted just to wear a t-shirt and some leggings under your drysuit. On short dives, that may even suffice. However, on long dives, having a little more padding between your body and the shell of your suit is more comfortable. Combining a wicking base layer with another thin-ish layer works well for me. But from 25 degrees and two hours onward, I tend to be in a proper undergarment (with a finetuned pre-dive routine and cooling off before the dive).
Solution 5: Ask for Help
I don’t ask for help easily, and as technical divers, we train to be self-sufficient. But we also train to work in a team, and that includes knowing when to ask for help.
When it comes to preventing overheating, that can take several forms. If you’re shore-diving, spend a few minutes on the surface allowing your body to cool down before you descend. Tell your teammates why you’re doing this. You’re effectively looking out for the team.
On a boat, it can be easier to manage the drysuit clock and getting ready in a breeze. If you’re still overheating, ask whether someone can pour a bit of water over your head while you’re waiting for your drop. If you’re putting on a gear configuration with multiple stage tanks, ask for help. Not because you’re unable to put on your gear yourself. But because you may have to strain less, be done quicker and avoid overheating with that little extra help. Sometimes you don’t have that luxury, but when it’s there – use it.
Last But Not Least…
Remember to stay hydrated throughout your diving day. Proper hydration, starting 24 hours before you dive, makes a big difference to decompression efficiency and how you feel after your dive.
Whether you dive wet or dry, overheating can cause serious problems. Minimise those risks by finetuning your pre-dive routine with your time, cooling off before you get in the water and asking for help when you need it. By the way, if you have any tips to share, feel free!