Sure does increase it! A definite drawback!
But lots of trapped warm air means lots of weight.
It also means I'm comfortably warm up to about two hours in the low 40's. Below 40, about 90 minutes of great comfort is typical, even down to the low 30's.
That's for someone with a tendency to get cold quicker than most people, I think.
Especially on my typical low-activity photo dives.
If you're interested in how much more weight, here are my typical set-ups.
My set-up for 45-60 degree water is:
- 100 gm polypropylene long underwear
- 300 gm Polartec
- a four-layer fleece chest pad about a half-inch thick by 12x18"
- one or two layers of socks
- neoprene 3mm ice cap underhood and 7mm overhood
- drygloves with one or two liners
My minimum weight required for saltwater using HP steel 120 and al30 pony and this thermal protection: 37lbs.
I use about 4 extra lbs because I like the increased warmth.
My set-up for 30-40 degree water is:
- 100 gm polypropylene long underwear
- Weezle Extreme Plus
- the thick fleece chest pad as above
- two layers of socks (one being Weezle)
- same hoods
- two dryglove liners
- two 3mm neoprene neck bands
My minimum weight required for saltwater using same tanks above and this thermal protection: about 46 lbs.
Again, I'll wear an extra 6 to 8 lbs above that minimum because I've found the extra air is warmer.
And, to add more fuel to the expected controversy, I use only the drysuit for buoyancy control.
For the 40 to 45-degree water, I might add a third layer of fleece or wear the Weezle Extreme Plus.
If I'm doing active dives, like scalloping for instance, I might reduce my undergarments by a third or more. Also, I could get by with less insulation for planned shorter dives.
Generally, I'm just finning very slowly, stopping often, poking around and snapping a few pics and staying in the water a long time.
Nice and toasty, I might add!
Dave C