Sorry for all the self-quotes below, but they might provide more clarity.
I agree with you completely that the weighting primarily depends on the thickness and the loft of the undergarment.
In this we are in perfect agreement. So can you and Tstorm give some insight into what undergarments you're using? The only thing I can compare it to, is the DUI 400g which I wore with the 400g thinsulate booties in a TLS350.
I'll list my setup at the end of this post, but the DUI 400G is probably similar in buoyancy characteristics, at least based on seeing a friend use one.
He's about 3-inches shorter than I am and wears about the same amount of weight with a CF200 and the Thinsulate 400g.
Maybe it doesn't make sense because all the variables aren't readily apparent.
Which variables am I missing? Diver (allot 10 pounds). Gear (negative). Suit (neutral, undergarments (buoyant). What's missing?
You may not be missing anything significant, but, generally, I was thinking about undergarment buoyancy factors such as compressibility (retention of loft), stiffness and excessive size (which might tend to create folds).
I'd also consider other factors such as the shallowness of the dive (which might preserve high loft), the possibly greater internal space in the boots and/or drygloves and even whether the neoprene items are more buoyant than most.
I don't doubt Tammy for a second, since she's said that 50 lbs was what she needed after gradually adjusting the weights.
I am not trying to cast doubt at all. I am trying to understand what could possibly cause a diver to need to wear so much weight. A LOSS of that weight underwater would be absolutely catastrophic. I hope it's distributed and not all on a belt.
That's a great point about the danger of suddenly releasing a substantial amount of weight! I consider it one of the biggest dangers I face.
To avoid that, I made a shoulder harness for my 38-lb belt that will keep it on me should the buckle come loose. (My other reason for a harness was for getting the strain off my front zip when walking to and from the water.)
I may switch to a backplate and wing someday just to transfer the weight, not to mention all the other advantages over my jacket bcd. I'm real slow to make changes....
At the risk of starting the "good divers wear less weight" discussion, I also use large amounts of insulation and lots of weight, especially in the winter. So do my winter diving buddies....at least the ones who are warm like me for extended dives.
This is not about good and bad divers. It's about understanding divers in different environments. So I am asking what is a "large amount of insulation? Are you wearing significantly more than 400g of Thinsulate? In preparing for my dives on the great lakes, I plan to wear that undergarment (or something similar) along with some underarmour and perhaps some long johns. Are you wearing more than that?
I've heard that Thinsulate 400g is on par with the Weezle Extreme Plus that I use. People love them both.
A few days ago, I wore my usual winter undergarments in 40-degree saltwater and wore close to the minimum amount of weight needed: 51 lbs of lead.
I'm sure you're
not asking what I mean by minimum, which is the lowest amount of weight (at the surface with empty tanks) that would still allow me to get neutral after thoroughly venting the bcd and suit.
I think you're referring to what accounts for my needing 51lbs, which is detailed below.
I actually would've preferred about 2 or 3 more lbs at the end of the dive, since I drained both my HP120 and my al30 and it was hard to vent that last little bit to get neutral. Normally, the al30 stays full and unused.
I see you are diving a single steel, and your AL30 would have been neutral to slightly buoyant. My twin 108s would probably give me another 12 pounds over you.
That sounds accurate.
54 lbs is usually my preferred saltwater winter diving weight.
I have no reference for saltwater in my drysuit yet.
IIRC, you're a big guy, so it might be more than the typical 4-6lbs, as you know.
That might surprise some or draw ridicule....but on that day I was "toasty" warm in the 40-degree water for two long, low-activity dives.
Not surprising at all. If you dress well, you should be warm.
I also avoid constriction of body parts, especially extremities, to keep the warm blood flowing.
First dive's duration was 2hr 5 minutes.
SI of 1hr 15min. Air temp of 40F.
Then the second dive for 1hr 50min.
I won't go into the various elements of my thermal protection, but it is that buoyant! And it is that warm!
I think it would shed a lot of light if you DID go into your elements of thernal protection. That's the missing piece of the puzzle.... Don't keep how you're staying warm for 2 hours a secret!
Well, I'm glad you asked that question....
Actually, I want to avoid sounding like a blowhard, but if you really want to endure some stupefying details, they are in my posting linked below.
http://www.scubaboard.com/forums/in...-f-water-ne-usa-but-warm-here-scubaboard.html
Otherwise, I'll summarize here. I'd hate to put you into that
other long post, one is enough!
- CLx450, roomy, mobile fit even with max insulation
- Rockboots 1-sz oversize, laced loosely (CF200 suit socks are also oversize)
- Henderson 1/8" neoprene Ice Cap underhood
- DUI Warm Neck 7mm neoprene hood
- 2 homemade 1/8"x2" neoprene neck bands
- Oversized, wide view mask that seals to the Ice Cap
- Weezle Extreme+ (Plus)
- 100 wt polypropylene long underwear
- homemade 4-layer fleece chest pad 12x18"
- thick wool socks
- Weezle socks
- SI TECH drygloves, roomy fit
- 2 pair of polypropylene glove liners, one larger than the other
- Mares Quattros fins
- SeaQuest Spectrum 2, a lightweight jacket bcd
- PST HP120
- Al30 on a Highland SS pony band
- 51-54lbs of lead for saltwater
For me, a sedentary nearly 57-year old guy, with a turtle's metabolism, doing low-activity photo dives, this setup keeps me so warm, even down to the low-30's, that I'm not even aware of any cold areas until well into the second hour, and then they are minor.
The long 40-degree dives last Saturday were wonderfully and completely comfortable.
At the end of the second dive, I noticed a coolness in both of my insteps. I think I may have shoved my Rockboots into the fin pockets too far, creating a pressure point or constriction point. That was the only thing that didn't feel like living-room warmth that day.
In addition to the extra insulation, I think avoiding constriction has been key for me. I'll notice some coldness if I lace the Rockboots tight, or use a tighter glove or tighter glove liners or have my knife strap too tight on my leg, or even bending my elbow constantly while holding the flag line handle.
Since I'm thinking about getting new Quattros, I may go to the next size up to avoid the tight fin pocket, but that's usually not a problem if I don't shove them in too deeply.
Oh, it may be just my imagination, but I think I may be significantly warmer because I use only my drysuit for buoyancy control, but I understand the pros and cons of this for people, so I don't push it on anyone.
One more thing that might add to my buoyancy is that my undergarment is a little big on me. I just fold over about 3-inches of excess torso length in the low back and abdomen. Maybe that keeps my kidneys and gut warmer, an unintended benefit.
I also try to avoid heat loss prior to the dives. It was 20 degrees outside while I suited up Saturday, but I kept warm in a snowmobile suit, balaclava and gloves.
Any thoughts, PerroneFord? I'll bet some of this sounds pretty strange....
Dave C
