Is there an undergarments rule of thumb?

[Ryan Neely]

Note: I understand that everyone's experience is different. I also understand that opinions on ScubaBoard are strong and varied. I am not seeking advice on branded vs. non-branded gear but, instead, on general guidelines that can be applied to everyone.

Question: Is there a rule-of-thumb guideline for choosing the amount of warmth needed for drysuit undergarments?

I've scoured the archives and have seen a huge amount of information regarding "best" undergarments. This brand is better than that brand. Non-brands are better than brands. This material over that material. It's all been very enlightening, but it hasn't helped me get a feel for where to start when it comes to cobbling together my first undergarment kit.

Everyone's temperature tolerance varies. I get that. For me, I need a jacket and long pants when standing motionless in the shade on a sunny 72° F day with a mold breeze. When walking at a mold pace on that same day, I would likely need only a pair of shorts.

So, my needs won't match everyone else's needs, which is why I ask about a general guideline rule-of-thumb.

Think about the adage espoused to people new to running: "Dress for your run as if the temperature was 10° warmer than it truly is."

That's universal and can be applied to everyone's unique physiology as a starting point.

Is there anything like this for diving, specifically as it relates to drysuit undergarments?

 

[runsongas]

100g insulation for every 5C/10F below the temperature you are comfortable diving in a rash guard is a rough estimate.

 

[Bigbella]

A great deal of what you ask, falls to personal taste. My insulation needs, for example, vary with the season and the type of drysuit in use.

My Winter go-to set, are Climasphere undergarments from Scubapro -- one or both included layers; but often a cheap pair of sweats will fit that bill as well, especially, when I've forgotten those garments in the dirty laundry; so too, some decent long underwear has been put to use, from time to time, in lieu of specialized apparel . . .

 

[Zef]

How much insulation one needs under their drysuit varies from individual to individual. As a ski instructor and divemaster, my recommendation is similar to the advice you will find for most outdoor activities..."Layer".

Before investing in any specific undergarment, start with some affordable options for layers. Do a dive and log the water temp and what you wore under your drysuit. If you were not warm enough then on your next dive in similar conditions, make a change by adding a layer or changing to a thicker layer. If you are too warm, then on your next dive in similar conditions remove a layer or reduce the thickness of your insulation. Be sure to log what you wore and how you felt (cold vs. warm, how long into the dive you became cold, etc.).

Note: A good wicking base layer can make a major difference.

Once you have any idea of how much insulation you need for different water temps, then start researching specific products to meet your needs.

There are also occasions with drysuit diving, at least where I am located, where the air temp is colder than the water temp....and there are plenty of times when the air temp is much warmer than the water temp....sometimes the right amount of insulation is a compromise between comfort in the water and comfort or tolerability out of the water.

It doesn't take too many dives to figure things out, and usually what one wears under their drysuit will work for a range of water temperatures.

Note: Be aware that diving above or below a thermocline can have a major impact on what one wears under their drysuit....there is a quarry not far from my house, the surface can be 20c and it will drop to between 10c-12c below the thermocline (at @ 10 meters) in the middle of summer. The difference between the top layer and the bottom layer is less in the winter, but in the summer, in this particular quarry, I dive wet/semi-dry if I am staying shallow and will dive dry with some insulation if I plan to be below the thermocline for any length of time.

-Z

 

[Esprise Me]

DUI has a whole chart. Even though it's meant to tell you which DUI undergarment to buy, it might help with other brands too since the weights are listed: DUI | Drysuits & Diving Equipment from Diving Unlimited International

I haven't personally experimented with different undergarments; I just bought the one I rented for the course because I liked it, and it's been working for me. It's also what this chart would've recommended.

 

[stuartv]

I don't know of any rule of thumb that works. Other than pick something and go dive.

A rule of thumb would have to be pretty complex to even be remotely useful. What is warm enough for you at, say, 45 degrees could totally depend on how warm the air temps are on the surface, how many dives you're doing that day, and how long the dives are.

One short dive on a hot day and a single 100gsm undergarment might be enough.

3 x 1 hour dives on a day when it is 40 degrees topside and you might need a 400gsm undergarment - for the same water temperature.

 

[martincohn]

Check the manufactures site for your undies. They may have a temp guide to get ya started.

 

[formernuke]

I'm going to reinforce layers. In summer I wear a light layer as air and water temp drops I add layers.

Also a good wicking base layer helps a lot, i like merino wool personally but others like under armor etc.

Wear nothing cotton under the drysuit, this includes socks and underwear. There will be some moisture in the suit from sweat and or condensation.

 

[KentB]

I am a warm person I’m very rarely if ever cold. I also have some permanent built in insulation.

However as I’ve progressed in diving I find I get much much colder than I used to.
I do love my fourth element undergarments . I dive with the arctic and a heated vest primarily although I do have a halo which is nicer for the winter.
Water temps from 41/42-52*F ish and usually do 80-120 min dives
I also know people who prefer a drysuit in low 70s temps.

a good wicking layer is huge IMO

 

[Darnold9999]

My rule of thumb is to wear the layers I would wear in similar air temperature - if I was just standing in the shade and doing absolutely nothing for the same period of time - i.e. no external source of heat to keep warm. More if it is a long dive or multiple dives for the day.

You are going to be losing heat faster in water than just standing in air, but you will be working a bit harder swimming so roughly balances out.

It doesn't take many dives to figure this out and having layers that you can add and subtract gives you flexibility to use your drysuit in a range of temperatures.