Thicker Wetsuit and slower metabolism equals longer dive?

[diveDavedive]

We were having discussion on a dive boat the other day. The dive master had on a 6/7/8 mm full, hooded wetsuit in Cozumel, the rest of us in 3 mm shorts and longs. The main reason he wore that thick of a suit is, he said, is that it slowed his metabolism down noticeably so he was better able to lead dives and conserve more air.

I get being warmer and being more comfortable and diving longer because I am not chilled, but can being that warm make a noticeable difference in extended dive time due to slowed metabolism? Seems plausible at first but are we talking a few minutes or ten or twenty minutes?

Does anyone have some experience or insight in this or any impirical data supporting this claim or is it a fish tale??

Thanks

 

[RJP]

We were having discussion on a dive boat the other day. The dive master had on a 6/7/8 mm full, hooded wetsuit in Cozumel, the rest of us in 3 mm shorts and longs. The main reason he wore that thick of a suit is, he said, is that it slowed his metabolism down noticeably so he was better able to lead dives and conserve more air.

I get being warmer and being more comfortable and diving longer because I am not chilled, but can being that warm make a noticeable difference in extended dive time due to slowed metabolism? Seems plausible at first but are we talking a few minutes or ten or twenty minutes?

Does anyone have some experience or insight in this or any impirical data supporting this claim or is it a fish tale??

Thanks

How on Earth would a wetsuit - of any type or thickness - slow someone's metabolism?

 

[dumpsterDiver]

A warm wetsuit may not slow your metabolism, but being cold DEFINITELY can cause your metabolic rate to increase.

That is the whole idea of shivering. Also, the only way to really warm up when diving is to swim hard and get the thighs pumping, it helps a lot, but your air consumption goes through the roof. Just ask a macro photographer.. they go nowhere and try to stay super calm and breathe slowly.. they get colder much faster than an active diver.

 

[drbill]

The fact that your core temperature remains warm would slow metabolism. I know when I dive our local "cool" waters (say down as low as 46 F on occasion) even in a 7mm wetsuit I get significantly shorter bottom times than on similar dives in warm water (say 80-95 F) in a full 3/2mm wetsuit. My dives here off Catalina generally do not exceed 60-90 minutes whereas most of my dives in the Philippines were 90-120 minutes with some exceeding that

 

[emoreira]

Two things here.
1) The guy is a dive master. While a diver does a 2 tank excursion, usually the dive master remains in the water much much longer, and so he loses more heat.
2) As what a wetsuit manufacturer told me some time ago, a diver can die of hypothermia, but he knew no diver that died of hyperthermia in the water.

 

[Saltyhawg]

In tropical water I don't see any way it could make any significant difference. As was mentioned above, being cold difinitely speeds energy use through shivering as the body tries to maintain temp. Other effects are vasoconstriction in the skin/extremities and shunting of blood away from the gut...none of which are desirable while 75 feet below water. What water temps this happens at probably varies depending on your metabolism, body habitus and dive experience (trim, bouancy control, how relaxed you are). Purely my opinion with no proof to back it up....YMMV.

In cold water, I can definitely see it making a difference.

I say go with what works for you. Placebo effect is still an effect!

Was the dive master named Antonio?

 

[g1138]

Pseudo-science; I doubt he measured it so he's speaking casually.

When I'm real cold, I tend to breath more often and in quick short bursts as I shiver.
When I'm toasty, I'm so relaxed and my breathing is much longer and more fluid.

I think that's what he equates to slowing his "metabolism".
Theoretically: the less you shiver, the less energy you're burning off, the less your metabolism ramps up to restore that used energy.
Does it make a significant difference? Dunno.

 

[dumpsterDiver]

]In tropical water I don't see any way it could make any significant difference.[/B] As was mentioned above, being cold difinitely speeds energy use through shivering as the body tries to maintain temp. Other effects are vasoconstriction in the skin/extremities and shunting of blood away from the gut...none of which are desirable while 75 feet below water. What water temps this happens at probably varies depending on your metabolism, body habitus and dive experience (trim, bouancy control, how relaxed you are). Purely my opinion with no proof to back it up....YMMV.

In cold water, I can definitely see it making a difference.

I say go with what works for you. Placebo effect is still an effect!

Was the dive master named Antonio?

In tropical water it won't make a difference? People will be losing more heat than they can produce in water that is somewhere around 86 - 88 degrees.. that is my estimate. Obviously, work load, body shape, insulating fat percentage and basal metabolism all are factors.

The main point is that you can get cold, very cold in relatively warm water. I've read that in some instances being cold in warmer water can present additional risks. Supposedly, if you are cooled very slowly (as in relatively warm water with inadequate thermal protection), your core temperature can drop pretty significantly (over time) without the person really sensing it, or feeling a lot of discomfort. In really cold water, the shivering reflex is initiated not just by the drop in core temperature, but also by the rate of the temperature drop. Intense shivering is pretty easy to detect.

My personal experience with diving in cold water and with a thick wetsuit is that as I get chilled at the end of a dive, my breathing rate may not change significantly, but my air consumption goes up a lot. This caused me to run low much faster than I expected at the end of my dives. It took me a while to realize that as my metabolic demands increased from the cold, I was not breathing faster, but was breathing deeper- causing the elevated consumption.

 

[TMHeimer]

From what I've read, you can remain in 91 or 92F water indefinitely without ever getting cold (guess your body will compensate though it is at 98.6). So I guess anything less than that eventually will get you cold enough to affect air consumption. Now when it is really cold (below 40F) in a wetsuit, I am well ready to exit without figuring out the difference in consumption from say 50F.

 

[Bob DBF]

2) As what a wetsuit manufacturer told me some time ago, a diver can die of hypothermia, but he knew no diver that died of hyperthermia in the water.

Considering how little is known about the actual cause of any SCUBA death and my own experience related below, I believe it is a real stretch to come to that conclusion.

I have made two rescues on hypothermic divers, the first was easy as it was my buddy at the end of our dive and was coming out of the water even if I had to drag her out, which was pretty much the case. The second was catatonic on the bottom and, I believe, his buddy was leading and never knew he was missing. Both remembered starting the dive, getting cold and deciding to tough it out instead of thumbing the dive, and then blank until they were out of the water and warming up.

On the first occasion, I spent a bit of time trying to figure out how someone could get narked in 40' of water, because that was what the symptoms looked like to me at the time. The second was a little deeper, but I didn't screw around trying to figure out what was going on, as soon as I saw he would not respond properly to me, I took him up and got him out of the water.

In my not so expert opinion, I believe both would have stayed in their last position and just breathed until the air ran out. Someone looking at the accident would jump to the conclusion that the OOA caused the accident instead of being the result of hypothermia.




Bob
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That's my point, people, by and large, are not taught that diving can be deadly, they are taught how safe it is, and they are not equipped with the skills, taught and trained to the level required to be useful in an emergency.