Trimix in a wetsuit?

[MORGAN]

I'll be taking a normoxic trimix class in north Florida in October. I have a drysuit, but prefer to dive wet. My drysuit has no P-valve, as I only use it when it's too cold for a wetsuit and my dives in cold water tend to be shorter. My longest dives by far are cave dives, which to this point have all been in a wet suit.

I'm used to cold and cold water, and don't get cold easily. Cave diving I wear a 7mm wetsuit with a 5mm core warmer, and am comfortable in the north Florida caves. After two hours I start to feel a little cool, especially during deco, but not enough to be uncomfortable. I am wondering whether the higher thermal conductivity of trimix is likely to cool me off enough to be a problem in a wetsuit.

Is there anybody diving trimix in a wetsuit, or is it a bad idea? Looking for guidance and opinions.

Thanks,

Mike

[Tegg]

You will compress the wetsuit into uselessness fairly quickly if you are diving at real trimix depths.

[moody]

I did it once on CCR, 30min at 230ft and about an hour of deco, in 78 degree water, I am in no hurry to re do that, I'll be doing it dry from now on. Don't get me wrong, it's manageable just wasn't fun, and diving is supposed to be fun. I had a 7mm with hooded vest. I also don't have a pee valve on my dry suit so it's hold it or diapers!

[sskasser]

You will compress the wetsuit into uselessness fairly quickly if you are diving at real trimix depths.

Yep, crushing it would be my concern. I've seen them go really thin really quickly.

[Andreas]

I am wondering whether the higher thermal conductivity of trimix is likely to cool me off enough to be a problem in a wetsuit.

You might FEEL colder, but breathing a Helium-mix will actually make you lose heat slower than with a Nitrox-mix. Conductivity is likely not the biggest concern in heat-loss since it is only the small area of your regulator that is the conductor between the gas in your lungs/mouth. More important is likely how much energy it takes to heat the breathing gas on the way to your lungs (specific heat capacity), and if you do the math you will see that it takes less energy to heat a Helium-mix than the same volume of a Nitrox-mix.
But, most people are likely aware that a Nitrox-mix will make you FEEL warmer. (Remember when it was popular to decompress on air from 190' after a deep trimix dive and how warm you felt once you switched to air..? )

I agree with the rest; crushing of the neoprene should likely be your biggest concern (unless you have that expensive nitrogen-blown Rubatex stuff).

Cheers,
Andreas

[snakedoc]

I'll be taking a normoxic trimix class in north Florida in October. I have a drysuit, but prefer to dive wet. My drysuit has no P-valve, as I only use it when it's too cold for a wetsuit and my dives in cold water tend to be shorter. My longest dives by far are cave dives, which to this point have all been in a wet suit.

I'm used to cold and cold water, and don't get cold easily. Cave diving I wear a 7mm wetsuit with a 5mm core warmer, and am comfortable in the north Florida caves. After two hours I start to feel a little cool, especially during deco, but not enough to be uncomfortable. I am wondering whether the higher thermal conductivity of trimix is likely to cool me off enough to be a problem in a wetsuit.

Is there anybody diving trimix in a wetsuit, or is it a bad idea? Looking for guidance and opinions.

Thanks,

Mike

Did my trimix in a 7mm/5 mm hooded vest at Eagles Nest (approx. 73 F. at the time, max depth 270 ft. with runtime approx. 90 minutes) ONLY got a chill at the very end. I'm a relatively thin person who gets cold easily. You're used to cold water. You'll be fine... and you can pee whenever you want.

[a64pilot]

I wouldn't even consider Tri-mix wet, but then I'm a wuss, seriously you might be OK, until deco, then your gonna freeze

[diverdarren]

I would reccomend that you always use a dual-bladder buoyancy compensater when tri-mix diving in a wetsuit, and to use a drysuit inflator bottle with air in it when tri-mix diving in a drysuit. As to whether tri-mix diving in a wetsuit is a good idea or not, no two people have identical tolerance to cold water so you should use your own knowledge of your personal tolerance as well as your past experiences to judge for yourself.

[jeandiver]

I did my normoxic class at Eagles Nest in my 7mm. I did not have any issues with it (SMILE)

Jeano

[deepdiverbob]

I did my trimix class in a 7 mil, here in Missouri. Bottom temp at 200 feet was 42 degrees, but the lake we was training in, the deco was in 75-80 degree water from 30 foot on up. I dive wet as much as possible as well. I did Eagles Nest in my 7 mil, and didnt have any issues. Now, when I dove to 225 in Cannonball, I got chilled on the ascent line, water temp was about 50 degrees. I found my limits that day, anything deeper in Cannonball and it will have to be dry suit for safety and comfort.