For people using heated undergarments . . .

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LCF
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Re: For people using heated undergarments . . .

Postby LCF » Wed Nov 13, 2013 10:57 am

Here's the link to the original study, for those who like their data unfiltered: http://archive.rubicon-foundation.org/x ... 56789/5063
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Re: For people using heated undergarments . . .

Postby ljjames » Sat Nov 09, 2013 11:44 pm

When Lamont tried his heater vest for the first time, his first words to me (I'd been using one on pretty much every dive for couple years prior and apparently not telling him how awesome it was because it took him ages to get one of his own) was... "you little slut" :) He's biased.
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Re: For people using heated undergarments . . .

Postby Joshua Smith » Sat Nov 09, 2013 9:01 pm

Norris wrote:My google plus post linking to my twitter post with Lamont's link.

https://plus.google.com/109108885591531 ... mWkXquT2Pz


Could you fax that to my Myspace page and send me a hard copy?
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Re: For people using heated undergarments . . .

Postby Norris » Sat Nov 09, 2013 6:42 pm

My google plus post linking to my twitter post with Lamont's link.

https://plus.google.com/109108885591531 ... mWkXquT2Pz
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Re: For people using heated undergarments . . .

Postby lamont » Sat Nov 09, 2013 5:43 pm

blog post of mine made shortly after trying a heating vest for the first time:

http://blog.scriptkiddie.org/2010/11/16 ... s-are-rad/

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Re: For people using heated undergarments . . .

Postby LCF » Sat Nov 09, 2013 4:25 pm

Well, no matter what some people think of the heated garments, people ARE using them, and they were definitely being hawked, both for under dry suits and for under wetsuits (Thermalution) at DEMA. I didn't start the thread to get into an argument about whether you should have a vest or a better UG. I just wanted to pass along the information that, if you do have one, you shouldn't just dive and not think about it.

I've tried just about every undergarment that is out there to be worn. I still get cold. I like my vest. I see nothing at all wrong with that!
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Re: For people using heated undergarments . . .

Postby Jeff Pack » Sat Nov 09, 2013 9:19 am

Remember I'm doing 1.5 hour plus dives as well, but I guess for diving being a fat@ss is a plus sometimes :-)

I might have to try so another set of undies, but no lofting types.

Reading about the board seems to come down to santis bz400,, the halo,or perhaps waterproof warmtec 300, anything else?
=============================================

- I got a good squirt in my mouth
- I would imagine that there would be a large amount of involuntary gagging
- I don't know about you but I'm not into swallowing it

CCR discussion on Caustic Cocktails.

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Re: For people using heated undergarments . . .

Postby LowDrag » Sat Nov 09, 2013 8:44 am

I feel lucky after reading this thread. It has to be really cold for me to need to put on my Under Armor and my Thermal Fusion at the same time otherwise I sweat like crazy. My last dives were at Sunrise about three weeks ago and I went from using both layers to only using the TF and I was great. I wore the TF on our night dive and felt quite warm through the entire dive. Must be all the bioprene I am carrying around right Jeff? :rofl: LOL!!!

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Re: For people using heated undergarments . . .

Postby ljjames » Sat Nov 09, 2013 1:08 am

I'm with Richard here. If you get cold, add the insulation and deal. If you bump up to real 400g thinsulate have a CF200 and dive a rebreather and STILL get cold for the length of dives you are doing then add a heater vest and use it sparingly on the bottom.

Suit heat is awesome. I love it on recreational dives and before i was diving the rebreather a lot i used it on almost every dive. I get stupid when i get cold, my narc increases. If i have a suit heater, it honestly feels like the narc and stupid factor seems less. I've talked to a couple folks that do much much much more aggressive dives and they report turning on the heater to take the edge off from time to time on long long exposures... flick it on during a bottom gas switch for a few minutes. Now that i'm on CCR on most dives i'm so much warmer that i have not used the suit heater since last fall.

and yes, bioprene matters, a 5lb weight difference matters to me, but then again, so does getting up at 6am to go for a dive (I don't thermo-regulate well when i'm tired)

The bottom line is i hear a TON of people who are recreational divers looking at going to suit heaters so they don't have to wear as much weight. THESE are the people who need to be paying attention to the issue of 'cold to warm'. These are the people who are at increased risk for a DCS hit if they are pushing the edge and loose battery power near in final 1/3 of dive and are wearing inadequate undergarments...

FAR more concerning to me is the system people choose. I worry about systems that put the battery in the drysuit, NOT because of concern about suit flood and battery, but because in the event of a short circuit in most internal systems there is absolutely NO WAY to interrupt the current without ripping your suit open. I have seen shorts happen in both wired and polymer panel suit heaters. A canister is an added bother, but at least this way you know you can unplug.
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Re: For people using heated undergarments . . .

Postby LCF » Fri Nov 08, 2013 10:00 pm

I've actually found that the TF is as warm as my MK3, but not nearly as bulky.

But anyway, people can do what they like; I just think it's important to pass along the information that the magnitude of the change in decompression risk with temperature is far greater than I knew, and is supported by good science (and I will have the article reference within a day or two, and will add it to this thread). I have now filed the heated garment under "dive must be planned and executed as though it didn't exist".

Richard, people who like to spend the entire dive sitting in one small area hunting macro critters to photograph get VERY VERY cold! :)
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Re: For people using heated undergarments . . .

Postby Jeff Pack » Fri Nov 08, 2013 7:50 pm

I was ok until I lost the weight

I still have my mk3, but thos lofting garments vent like a plugged toilet.
=============================================

- I got a good squirt in my mouth
- I would imagine that there would be a large amount of involuntary gagging
- I don't know about you but I'm not into swallowing it

CCR discussion on Caustic Cocktails.

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Re: For people using heated undergarments . . .

Postby CaptnJack » Fri Nov 08, 2013 2:38 pm

The "Thermal Fusion" is basically 200 weight polar fleece. Its no wonder you are freezing even with 60W of heat.

Whites doesn't seem to offer the Mk3 undergarment anymore. But DUI, Weezle and others offer undergarments which are far and away warmer than the 200 weight fleece thermal fusion.
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Re: For people using heated undergarments . . .

Postby Jeff Pack » Fri Nov 08, 2013 1:17 pm

CaptnJack wrote:
Jeff Pack wrote:I run my heated vest the whole dive so I probably wind up starting warm,then slightly cold at depth, and back to warm again on ascent.


This is what Neil Pollack is warning against (and has been for qite some time, he's written about this in Alert Diver at least twice in the past 5 years), if your battery dies you are screwed.

Better to turn the vest on briefly at the start to confirm its working. Then leave it off until you start your decompression. This avoid the issue of maxing out your on-gassing while being vasoconstricted for off-gassing problem.

Anyone whole requires heat on no deco dives should really re-evaluate getting new undies...


I get too cold now after all my weight loss. UA base Layer 1, UA Base Layer 5, Thermal Fusion, 10mm hood and 7mm neoprene socks, Merlino socks. Anything more and I'd look like the Michelin Tire man...

I can pull deco without the vest, but would rather not, that last time I did 40m deco w/o vest was no bueno. Enough to convince me to never ever do that again.

I tried the vest off at beginning, and turn on later, and couldnt get my core warmed back up after a 2+ hour dive. 60w heat isnt much. That vest was pretty much useless at that point.

So I leave mine on the entire dive.

I guess there's something after all to keeping that Bioprene... :)
=============================================

- I got a good squirt in my mouth
- I would imagine that there would be a large amount of involuntary gagging
- I don't know about you but I'm not into swallowing it

CCR discussion on Caustic Cocktails.

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Re: For people using heated undergarments . . .

Postby eliseaboo » Fri Nov 08, 2013 11:06 am

Score one for the Midwest thermocline! :partydance:

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Re: For people using heated undergarments . . .

Postby CaptnJack » Fri Nov 08, 2013 10:30 am

Jeff Pack wrote:I run my heated vest the whole dive so I probably wind up starting warm,then slightly cold at depth, and back to warm again on ascent.


This is what Neil Pollack is warning against (and has been for qite some time, he's written about this in Alert Diver at least twice in the past 5 years), if your battery dies you are screwed.

Better to turn the vest on briefly at the start to confirm its working. Then leave it off until you start your decompression. This avoid the issue of maxing out your on-gassing while being vasoconstricted for off-gassing problem.

Anyone whole requires heat on no deco dives should really re-evaluate getting new undies...
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Re: For people using heated undergarments . . .

Postby Jeff Pack » Fri Nov 08, 2013 9:07 am

I run my heated vest the whole dive so I probably wind up starting warm,then slightly cold at depth, and back to warm again on ascent.
=============================================

- I got a good squirt in my mouth
- I would imagine that there would be a large amount of involuntary gagging
- I don't know about you but I'm not into swallowing it

CCR discussion on Caustic Cocktails.

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Re: For people using heated undergarments . . .

Postby LCF » Fri Nov 08, 2013 6:17 am

This was a square profile (done in a chamber), so they took them down to 120 for the "bottom time", and then did a gradual, ascending deco for 80 minutes. So the water was at one temperature during the bottom time, and another during the ascent and decompression.

They were in swim trunks, so the heat loss to the water would be fairly fast -- but I would imagine that ALL of us who dive cold water are essentially working somewhere in the "start warm and end cold" model. I would imagine this is why we were all taught to treat our dives as though they are deeper and longer than the standard tables. I think what Pollock is really worried about is people who might run a heated undergarment from the beginning of a dive, and then perhaps run out of battery and have to do their ascent and/or deco cold (he did mention that). He also warned against assuming that heat on deco would allow more aggressive profiles, because if you DON'T run the UG during the dive, and then it won't turn on . . .

I don't know what the right answer is for how to use them, but the sheer magnitude of the effect stunned me, because it's much larger than I would have thought, and it made me scratch my head and think about how I could use my vest, not only for comfort, but for safety.
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Re: For people using heated undergarments . . .

Postby Tangfish » Thu Nov 07, 2013 10:44 pm

Wow, Lynne, this is very insightful data indeed!

So, if I'm reading this correctly it's best to start cold and end warm, and worst to start warm and end cold - is that right?

Also, what do you mean by "start" and "end", the first/last third of a dive, the first/last 10 minutes of a dive? Or does "start" mean when you reach the max depth?

I haven't used a heated undergarment yet (but boy do I want one), but when I think of my dives and temperatures it's usually starting warm because I zipped up my suit and I'm moving gear and myself into the water and I'm sweating inside the suit and stuff, and then about 10 minutes into the dive I cool down and then by the end I'm really cold. So does that count as starting warm and ending cold?

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For people using heated undergarments . . .

Postby LCF » Thu Nov 07, 2013 9:13 pm

I sat through a very interesting talk by one of the DAN folks (Dr. Neal Pollock) today, during part of which he presented a really impressive paper on the effect of temperature on decompression stress.

I'm not going to get the numbers perfect, but here's the gist of it: They had "divers" in water, the temperature of which was either 98 degrees or 80 degrees. (98 was "warm" and 80 was "cold" -- doesn't seem cold, except these guys were in swim trunks.) The "dive" was to 120 feet, starting for 30 minutes, on air. Deco was 80 minutes for all dives.

They had four groups: Start warm, stay warm; start warm, get cold on deco; start cold and stay cold, and start cold and get warmer on deco.

The group that started warm and got cold on deco had over 20% incidence of symptomatic DCS, even after 80 minutes of deco.

You were a little better off if you started cold and stayed cold, and a little better than that, if you started warm and stayed warm.

But the group that started cold and got warm could do SEVENTY minutes with, IIRC, about a 5% DCS risk.

That's a HUGE effect of temperature, and one of the things Pollock said was that he's very worried about the proliferation of heated undergarments, and the risk people may be running, depending on how they use them.

I personally have been using mine the last third or so of my dive time, but I'm going to change that as a result of what I heard today. The vest doesn't come on until I am definitely "on ascent" (even if that's swimming upslope), and I will try to run it part of my surface interval on the days where I'm doing more than one dive. No heat during the "bottom time" phase of the dive.

Just wanted to pass on this info, because I know there are people around here using heat, and I found this study pretty compelling.
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