Posted by Kendall Raine on August 19, 2002 at 15:06:32:
In Reply to: Re: Once again, Kendall. posted by snotty and indignant on August 19, 2002 at 12:23:01:
I should know better than to get into a debate with you since they always seem to go this way. In the slim hope that you'll get it this time, let's review the analysis. Two key issues: 1) buoyancy, and 2) gas capacity.
104's work fine for o/w provided you're diving dry. With a drysuit and thick underwear, I need 20 lbs of ballast to get negative. I'll need 20 lbs ballast to complete deco even if my tanks are empty. With empty 104's and a steel backplate I can do this. I can also do this with an aluminum backplate and a weight belt if I want a greater percentage of ditchable weight or need less weight overall (thinner underwear). As already pointed out, 104's are too heavy diving wet.
Now, as to your hypothetical worst case, if you totally flood your drysuit (e.g. sustain a massive rip along the back causing total loss of gas and an inability to reflate) AND lose your wing, you'll need to use your SMB to get up. Use of the SMB allows you to vent gas on ascent and so control your ascent rate. That's not something you can do by dropping your weight belt. A small tear or blown seal will typically not totally flood a drysuit because of positive pressure. In case of a leak, you'll want to be negative so you can blow up the drysuit to stay warm and prevent further flooding. Now, as for using 80's with a drysuit, you'll need a big weight belt, 20 lbs in my case, plus a steel back plate, to compensate for the buoyancy of the drysuit and the empty tanks. In the event you lose all buoyancy in your drysuit and your wing, dropping the weight belt will still leave you negative unless you've also lost all your back gas. True, you're much less negative than with 104's. The problem with that approach is if you lose the weight belt inadvertantly, you're dead. There is no way for you to keep from rocketing to the surface short of flooding your drysuit. In summary, I can survive simultaneously losing all buoyancy in my drysuit and my wing if I'm wearing 104's. If 104's are too big for you, use a smaller steel dry. With 80's and a drysuit, the loss of my weight belt will either land me in the chamber or kill me.
The advantage of having more gas available on the Moody (using 104's) includes not having to blowback a light trimix. You can make multiple dives without a refill and still have enough gas to help out another diver. If you're diving 80's on the Moody, you'll probably need a refill between dives if you run up any bottom time. As I said in previous posts, there is nothing wrong with using 80's on the Moody, wet, provided you do short dives or are willing to take a refill. The alternative to blowbacks is to use a stage of gas for the first dive and save the backgas for the second, but thermal issues come into play on any but a short dive if you're wet.
Honestly, if you'd just take the cotton out of your ears and put it in your mouth, you might learn something. What's written above is how diving is done when going straight to the surface to solve a problem is not an option. I know becaue that's the kind of diving I do, and have done, regularly, for the last ten years, in caves, wrecks, oceans and lakes. No accidents, no close calls, no chamber rides, nada. Have the last word if you like, but arguing with me about this stuff only makes you look silly.