A couple of weeks back I dived in my new (to me) tri-laminate dry suit. I'd done the dry suit course back in February in 3C water at Wrasbury and my thin base layer underwear had kept me comfortably warm (and had done so on a couple of later dives in warmer water). However, despite the water only getting down to a toasty 16C on my recent dives, I got very cold to the point of shivering uncontrollably after my second dive in spite of warm sunny weather. I'm wondering if the reason I got cold was somehow related to the depth I dived to (30M rather than 10 in Wrasbury) or some other factor. I've got a totally over the top undersuit now for my next dives, but does anyone have an explanation for why I felt so cold on my recent dives or was it just 'one of those things'? M
What sort of suit were you using when you did the course? Neoprene or "other"? There's a big difference between the thermal properties of a trilaminate suit vs a neoprene one - though this gets less as you go deeper and the neoprene squeezes. Did you put enough air in the suit this time round? It's surprising (IMO) how much you need to add as you go deeper. A suit with 10m levels of air in it will be cold (and squeezing you like mad) at 3om. When you say 16C - do you mean on the surface or at 30m? The difference between the two is considerable. It was about 17 on the surface at Stoney at the weekend, and 7 at the Hydrobox.
Should have said, I did the course in Tri-Laminate too and dived the other times in this suit when it belonged to someone else. I wasn't getting any noticeable squeeze, so I guess I had enough air in it. The 16C was recorded by my computer at max depth. Cheers, M
Wow - where were you where it was 16C at 30m? Sometimes it's just down to whether you got a good night's sleep or had a decent enough breakfast etc, but something doesn't add up here. Were you using hood and gloves etc? Keeping your head and hands warm is important.
Yeah, does sounds a bit odd doesn't it? This was off Weymouth - Was a nice day, but that nice???? I did have a hood and gloves on too as I expected it to be cold. I'll check my buddy's reading, maybe there's something up with my temp sensor... M.
Ok well 16C in the sea off the south coast doesn't sound *as* far fetched as at an inland site where there's no water movement. I suspect you simply didn't have enough on underneath the suit. Question really is why you weren't brass monkeys at 3c in Wraysbury. I've been freezing in there at warmer temperatures in a coated fabric suit with way more underneath it than you had.
What is your undersuit like when you surface, does it feel damp (sweat) as this can make your whole body cool especially in warm weather your body will sweat more and it all traps in the suit or within your thermal layers
You need one of these ... http://www.simplyscuba.com/products/WaterProof/D1HybridDrysuit.aspx It's not that expensive really
"Proper" base layer (not the most expensive, but wickable material). The comment about being tired or something might also apply. I'd had a bit of a stomach upset the previous morning and although I'd slept well the night before I was very tired before I went to bed, perhaps I was just suffering the after effects of that. M
A 30m dive will take a lot out of your body as you get rid of the N2 load. I was getting uncontrollably cold about an 1-2 hrs after a deep dive, the answer was eat more carbohydrates the day before and the morning of the dive.
I could also be the time you were in the water after watching some drysuit courses in the past the students were only in the water 15 mins max where this is only a short exposure to the cold water, I would say your dive would of been considerably longer which could be a factor in you feeling the cold more.
The dive was about as long as my drysuit course dives (35 mins or so), but I certainly didn't eat a lot the previous day, so that might well have played a part. Thanks for all the suggestions as I'm keen to understand the effects. M.
It's probably a combination of things. Like a plane crash is rarely down to a failure of a single component but more a "perfect storm" of failure on failure and circumstance. You were recovering from being unwell, underfed, probably dehydrated and tired. Add to that a dive three times the depth of that you've done before in a drysuit, the squeeze on your hood and gloves if not your suit itself, relatively thin undergarments which were already clammy with sweat and potentially a windchill on the surface that you wouldn't get at the relatively sheltered Wraysbury and it starts to look like a combination of factors. Probably some other things that no-one has considered yet too.
I also think that when your training, you are concentrating on doing skills etc, your brain is working at it's max (20% of your energy needs for 5% of body mass) and when using energy, there is a whole load of heat being generated. Now you don't have skills to do, and distract you from the cold, you will notice the cold. When I was learning to fly I was in a light-weight jacket, yet my instructor was in a big puffy jacket, I felt warm, but he felt freezing cold which was a very common effect between student & instructor. Once I had got my licence, I often felt cold, which also shows how working your brain, learning new skills, helps to keep you warm.
I can be fine at 2dg on a 40 min dive and other times i can feel the cold at 10dg inside 20mins. I think so many factors can effect you on any given day.
