How to avoid getting cold when diving?

Question

I've done a few scuba dives and really enjoy it, except (diving or not) I get cold quickly when submerged. I have very low body fat and relatively low blood pressure (though I am healthy overall) so it's not a surprise I get cold quickly. Even swimming in tropical waters, it doesn't take long for me to start shivering and getting uncomfortable.

The past few times I've had guided scuba dives, I wore wet suits and was in fairly warm water, but still got so cold by the end of a ~30 minute dive that I had trouble taking full deep breaths, I shivered for a while after getting out of the water, and in some cases I started losing mobility in my fingers (like how it's difficult to grip a pencil if your hands are cold for a while).

As I consider doing more scuba diving in the future - both in the tropics and potentially in colder waters if I can find a way for that not to be miserable - I wonder if I should invest in a dry suit or some other equipment to help me mitigate the cold. From reading the Wikipedia page on dry suits and their hazards, I understand dry suits can add some complication. I'm unfamiliar with these details for now, but I'm not worried about needing to learn new things as other than cold I've been comfortable scuba diving so far. Whether dry suit or some other option, how can I mitigate getting cold so quickly when diving? Again emphasizing the context: I get uncomfortably cold even in 30 minute tropical dives.

Note that I'm not just asking about what dive suits to use in different temperatures, as in this post. I'm asking about what to do to get over getting cold easily in any temperature water. While the two are related I think there could be nuance to answering my question, addressing unique issues to folks who get cold easily not just people diving in colder waters.

Answer 1

It sounds like you need your very own wetsuit, preferably one that is made for cold waters. Not sure if you can be too warm in a wetsuit, honestly, I am not an expert in this, but you definitely need a warmer one than an average person in a particular water temperature. And if you rent a wetsuit from a diving school, you get whatever they have available. You might try asking whether they have warmer suits, but I think in general, especially in tropical countries, they will not have much variety.

Another problem with wetsuits is that they have to fit you perfectly. It should be difficult (yet possible) to put it on/ take it off, and it should be as tight as possible. Because if there is any space for water/air in between the wetsuit and your body, you will be cold. I myself am tall, and when renting wetsuits in Asia I was constantly given ones that were way too big for me widthwise.

In case you decide to buy a wetsuit, you could check out this for choosing the correct thickness: Wetsuit Thickness Guide & Temperature Chart.

And this video for getting the correct size: Finding the Right Fit (Youtube).

Answer 2

As an answer that will be of immediate use without investing a lot of money:

You can wear two wetsuits, one over the other. I have done this in the past when the rental place couldn't provide a warm enough one in my needed size.

It will restrict your mobility a little, so this is certainly not an optimal solution - but it's cheap, and you can probably ask for it almost anywhere you're renting a wetsuit (maybe pay a bit extra).

Of course buying a properly fitted wetsuit in the thickness that you need is still the far superior option.

Answer 3

Consider a semi-dry suit. Here is a description of one from Scuba Doctor:

Semi-dry suits are effectively a thick wetsuit with better-than-usual seals at wrist, neck and ankles. The seals limit the volume of water entering and leaving the suit. The wearer gets wet in a semi-dry suit but the water that enters is soon warmed up and does not leave the suit readily, so the wearer remains warm. The trapped layer of water does not add to the suit's insulating ability. Any residual water circulation past the seals still causes heat loss. But semi-dry suits are cheap and simple compared to dry suits. They are made from thick Neoprene, which provides good thermal protection. They lose buoyancy and thermal protection as the trapped gas bubbles in the Neoprene compress at depth. Semi-dry suits can come in various configurations including a single piece or two pieces, made of 'long johns' and a separate 'jacket'. Semi dry suits do not usually include boots, so a separate pair of insulating boots are worn. They are used typically where the water temperature is between 10 and 20 °C (50 and 68 °F).

I too have low blood pressure and get cold easily, and use an Aqualung SolAfx 8/7mm semi-dry wetsuit. Diving in one feels great, but takes some getting used to. They are more expensive and less frequently used than regular wetsuits, so buying second-hand is a good option.

Here are a couple other links about semi-dry suits: Scubeo, suits for sale at Adreno.

Answer 4

I thought I would weigh in with the other method you mentioned. Drysuits. You would need to take a course to use it safely, there is more to it than diving in a wetsuit. As someone who primarily dives in a drysuit, they are worth the effort of learning.

Now to the aspects of the actual suit. The issue will be cost. Both for a course and the suit itself. The course, for me at least, cost £160. A cheap suit will be about £500.

For warmer diving I would suggest neoprene, it can be comfortable in waters up to about 24°c and with an undersuit down to about 5°c (at least that is the coldest I have been in comfortably)

A fair few people will tell you that a course isn't necessary, but I would strongly recommend it. With a course you can rent one and see if you like diving in them.

Answer 5

Use a drysuit. These insulate, are far warmer than a wetsuit and are an additional source of buoyancy.

Two varieties, neoprene & 'membrane'. Typically neoprene is cheaper so your first drysuit is neoprene then you move on to membrane.

To cut to the chase: membrane means there's little insulation, but there's hardly any evaporation so it's much warmer on the surface than a neoprene drysuit -- such as on a RIB motoring at speed back from a dive. All insulation is gained by your multiple layers of underclothes. This is great as you can change your undergarments to suit the conditions -- don't forget to adjust your weighting as you need more weight to counteract the additional buoyancy of the insulation. Membrane also doesn't 'squeeze' so doesn't change it's buoyancy characteristics during a dive as does a wetsuit or neoprene drysuit.

I "cheat" in the winter and use a (Santi) heated vest fed from a dedicated large 18AH battery through an E/O connector into the vest. You won't be warm, but you're certainly not shivering, especially important if you're decompressing. Also use drygloves with decent inner gloves, two (or three) layers of socks and a thick hood. Did a 100 minute dive in a 2 degree lake this winter and only boredom got me out of the water -- I had 5 layers on top: a thermal vest; thermal T-shirt; the heated vest; a long-sleeved rash-vest; a thick winter insulated long-sleeved top (Fourth Element Arctic Expedition).

I also use the same membrane drysuit in warmer condtions; it's great at 24 degrees with a thin layer of insulation. In fact I regularly practice with my drysuit in a 32degree heated pool.

If buying a drysuit, make sure it's fitted with large pockets on the sides. Also make sure the suit exhaust dump is on the side of the arm, not the front (which some manufacturers seem to think is easier to get to, not realising that you don't touch the valve during a dive - once you set it to wide open).

Then there's the solution to excess hydration: a "P" valve -- the second most valuable invention in diving after the demand valve! There's nothing worse than having to cut short a dive to keep the drysuit dry inside.

Some things to consider about drysuits:

• There's drysuit training courses. There's not much to learn but you must practice with them as there's issues with buoyancy. The difficult bit is the top 10 metres. It's soon mastered (tip, leave the dump open!)
• Most shops will throw in the drysuit course for free if you buy the suit
• You don't need a 'ticket' to buy a drysuit so don't pay another dollar in
• Fit is everything. Well, after being dry! You must be able to stretch upwards, crouch into a ball, stand up and reach your spine with your hand from over your shoulders (for valve shutdowns), lay down and bend your knees at 90 degrees (the standard flat diving position); make sure there's enough space for your thick winter undersuit.
• If you're not a standard size consider made-to-measure but make sure that they measure you so if it doesn't fit, it's their responsibility
• Expensive drysuits aren't necessarily better than cheaper ones: some brands are very overpriced
• Zips: back or front. Front's more expensive but way more convenient.
• Zips: plastic zips break and leak more easily than metal zips
• Boots or socks: I much prefer socks with separate rock boots as I can keep the muck away from my suit after walking across sand or carpark. Socks means the suit can be turned inside out for speedy drying.
• Socks+rockboots stop gas migration to your feet, so you don't get that floaty-feet feeling
• Buy a decent bag and ensure you fold the suit up properly every time
• Dry the suit thoroughly after every dive or it will stink (I hang mine up in the garage)
• Use a "HangAir" which is a big hanger with a fan to blow air into the suit for drying
• Cuffs and neck seals: neoprene is warmer and more comfortable, but tears easily and is hard to replace. Latex or silicone seals stretch more and and easier to don and doff
• Premium suits have user-replacable neck and cuff seals (Scitec Quick Neck) (Kubi glove rings)
• Membrane dries much quicker than neoprene
• Inflation nipple: use a standard BCD type so you can use the same hoses (there's some other types - CENJ - which aren't compatible)
• P-valves can be easily fitted after you've bought the suit. Once fitted they can't be easily removed (glue)
• Buying one second hand can be good value but be very careful about fit and leaking. You need a guarantee from the person selling it that it won't leak and it will fit. Be warned, you could be throwing away a huge amount of money on a suit that leaks and doesn't fit. If I were buying one, I would only do this on a sale-or-return basis -- I've seen far too many friends buying teabags. The only real way of finding out if it leaks is to do a long dive with dry underclothes.
• Second-hand suits are not worth much unless they're in very good condition with a guarantee/warranty.