Posted by MHK on January 17, 2001 at 17:36:07:
In Reply to: Re: A few more thoughts posted by seahunt on January 17, 2001 at 16:21:24:
Let's try this one more time...
1) As to you question could I compute your sawtooth profile on the fly, my answer is YES...
You and I debating this on the net won't get either one of us very far so I offer to meet you for a dive and prove it... You pick the site, you pick the profile and you use a computer and I won't and I gaurantee that I'll be within NDL limits...
But the follwing is an important point that I've said often and bears repeating so I'm going to put this is cap. letters ( and it also speaks to your point about the snip from another post )
CONTINUE TO USE THE COMPUTER WHILE YOU ARE GAINING THE NECESSARY UNDERSTANDING!!!!!!!!
Do not abandon the use of the computer until you can know the NDL limits.... As I posted earlier, when I was learning I began paying attention to every dive and started to keep track in my mind and then compare to what the computer said..
As for the pouches and Wetnotes, I'm not sure I ever used the word pouch, what I do is have 2 pockets on my wetsuit and/or drysuit..
In pocket I keep a spare mask and the other I keep Wetnotes with tables, jump spools, whistle, mirror and flares...
I would also add that to the extent that you believe there is some ambiguity and/or failed responses it may well be because you ask so many questions in every post.. I try to answer all of them and there is no intention whatsoever to be evasive or unambigious, it's simply a function of time and post length.. I try to be very accessible, I try to answer every question, but I do have a job ;-)
Do I read your comments correctly in that the biggest objection to the system is that;
1) the desire to eliminate the computer from the equation;
2) diving a steel tank while diving wet. ( I believe you agree that if you are diving doubles steels that you wouldn't use a wetsuit) Am I correct on the doubles point????
3) Computer console issue..
If I'm correct in the above let me address the points, if I missed something try to send me a shorter post with less questions ;-)
Let's start with the easiest and that in my mind is the console.. In terms of re-distributing the gauges that are normally on the console ( ie; SPG, compass and computer.. By clipping your SPG to your left hip D-ring with a custom length hose you can easily and quickly reach back and look at your SPG anytime needed. But more importantly by putting the other 2 items on your wrists you can instantly see the info simply by looking at you are. Proper trim provides for a diver to swim in a horizontal position with your head slightly titled down and with the feet slightly elevated.. If you have proper trim with you hands slightly extended you can look at info without ever breaking stride.. I believe that you are serioulsy overstating the issue as it relates to hunters.. As I said I dive every weekend, and I hunt bugs every weekend during the season and it simply isn't an issue and it does not preclude me from getting into any holes..
2) eliminating the reliance upon computers.. The most obvious problem I see is a diver abandoning the learning of basic decompression models.. We have been advised that Sport Chalet no longer requires learning tables if you buy a computer. This would be the equivalent of eliminating the need to teach basic addition and subtraction to school children because they will obviously use a calculator later in life. It is this diver dependance on equipment as opposed studying the impact of a variety of mixes that could make diving safer, add BT and be better for the body. Furthermore, most diving computers don't provide for Helium and IMHO anyone diving deeper than 100' should add He to the mix. Also, most dive computer add unecessarily to decompression times ( or more accurately take away from available BT) by discounting the benefits of deeps stops and in point of fact view this as *on gasing* time and then add that to the M-value time.. I've stated before that most computers tend to *bend* you at depth and then unbend you by requiring the diver to remain at 15' for extended periods and they simply ignore the benefits affiliated with deep stops. Another important point is that most computers don't allow you to adjust the conservation factor, you are stuck with what it comes with.. Assuming you have a *aggressive* computer that may work well in the 60' range, but if you are planning a 100' or 130' dive you may want to alter the conservation factor and/or reduce the gradient factor which can't be done.. You are then stuck with a computer that either is too conservative or too aggressive. And you also have computers that *lock up* when you go into decompression.. Let's assume that you are strictly relying on your computer and don't spend the underlying time to learn the stuff, and then you get lost inside a wreck, or you are hunting one of those 8 1/2 lb bugs, or for whatever reason your planned recreational dive exceeds you plan, now your computer locks out and absent an understanding of decompression theory, the knee jerk reaction may be to get to 15' asap and off gas. The reality is in this case when you need the computer the most it locks up.. Understanding deep stops and it's effect on off gasing the fast tissue groups could help you avoid a hit.. Also, few computers allow for gas switches in the vent you are diving air as your main gas and then desire to use an enriched air mix for accelerated deco and those that do are generally cost prohibitive, somewhere in the $800 - $900 range.
3) Steel tanks in a wetsuit. As I've noted I'm slightly less concerned about this issue when talking about a single tank, although I'd prefer the practice of AL - wet, ST - dry, but be that as it may lets examine the issue:
Any discussion of wet and steel needs to from the outset start out with a discussion of overall weighting, weight distribution and ditchable and non ditchable components.
Conventional weighting systems tend to position the bulk, if not all, of the weight around a divers waist, this creates a trim problem and should be avoided. By distributing the weight vis-a-vis the use of SS BP's, keel weights, light canisters, steel tanks or some combination thereof the diver needs to insure that he has sufficent ditchable weight in the event of a failed inflation source but by the same token one doesn't want to rocket to the surface if the weight is ditched.
AL tanks ( 80's) swing from 3 lbs negative when full to 3 lbs positive when empty, the steel tanks generally go from 6 lbs negative to 2 lbs negative and as such need to be considered when focusing on the weighting system taken as a whole. The concern of course is that should you loose your primary inflation source ( ie; your bc) you are then carrying non-ditchable negative weight and we therefore advise to use a alternative inflation source ( ie; a drysuit) when diving with steels..
It seems to me that there is a concentrated effort to find an excpetion to the rule and then therefore the floodgates can open and once that starts the temptation to bastardize the system and the integrity is too easy. Would using a single steel kill you if you lost you primary inflation, in most cases probably not, but I'm not sure it's worth the risk.. I'd rather avoid the problem to begin with, and as I said this is the approach we prefer.. We solve as many problems as we can before they occur, rather than worry about added failures points and proposed contingancies..
Later