Posted by seahunt on January 15, 2001 at 17:45:29:
In Reply to: Re: DIR on the West Coast posted by MHK on January 15, 2001 at 16:13:35:
Well, that is a lengthly explanation and I appreciate it. There are a few
things I can clarify per your comments, but also you state many critical points
that I just have to disagree with. I'll try to be brief and to the point.
As you mentioned, we seem to agree that DIR does seem to apply excellently
to tech diving...
>>We hope that diver's will take the time to learn the various decompression
>>theories therby rendering the reliance on a device useless.. In so doing you
>>do a couple of things:
Just what tables and theories are you using? No table or theory I know of adjusts
for a highly erratic profile such is common for hunters. All tables require you
to take an extremely conservative view of an erratic profile. As such, the
computer with it's continuous data sampling, does not have to act as conservatively.
This is especially true over multiple dives.
... Or should I just fudge my calculations to what I think is best?
Point (1) - Pucky. The computer cannot be replaced. If I suddenly have to go to
tables. As I have had to do, I know I'm going to have to cut out dives.
Point (2) - Pucky. What are these magical models. Are these different from
tables?
Point (3) - I still want to know what table will make you more accurate than a
computer such that you can evaluate a difference in BT of 10 minutes.
Point (4) - Without a computer, I can do repetitive dive calculations very well with
a table, thank you. If I cannot plan a single dive ahead of time, I do not expect to
be good at re-calculating repetitive dives underwater. I also sure don't intend to
plan to. That means I have made a huge up front mistake and don't know if I am pushing
the tables at some point. I don't allow that to happen. I know approximately where I
will be during a dive, before I go. If I lose track and am not sure, I surface and I
am sure I am in a safe situation. I make sure I never go into a deco situation without
planning it.
As for Part 2 - Points 1,2,3 - The reason I bring up the point is that I find 80
cu ft inadaquate and that the 100 cu ft steel is a much more desirable capacity. Also
I like carrying less weight. The difference between steel and Al empty is about
5 or 6 pounds. That is a small part of my boeyancy. Say I have a (almost) worst case
scenerio. I'm at 130 feet and my BC just explodes. It's not worst case, so I'm not out
of air.. a dry suit isn't going to help then either. If I have air, I can swim (yes,
with some difficulty) to shallower water where my boeyancy is not a major difficulty
and I can ascend casually from there. Really, this obviously isn't that big a problem
or the people that dive without a BC (myself previously and many people I know
currently) would not be able to make it to the surface and it just isn't that
difficult.
As for checking consoles for a buddies pressure, that is most convenient with
inexperienced divers, but is applicable with any. Why bother them? Most have to
think about it before responding and with a newbie that is undesirable. Actually,
I have no objection to buddy diving. I do it occasionally, but very rarely with a
diver that could assist me if a problem arose.
I personally have never used a cumbersome console, though I have seen some and
I have never had my console catch in kelp. I have had it hang in rocks infrequently,
and that is why when tight in the rocks (and some other reasons), I toss it up
between my legs. It stays there nicely. In coral areas, I use the BC retainer. A
console does make for some drag, but it is minimal and quite acceptable for the
benifits.
Now, of these points, the most critical one is what tables are you using that
work for sport diving better than a computer??? That means more bottom time with an
erratic profile during repetitive dives.
Your next point, steel with wetsuit, is suspect because of the number of divers
using steel with no BC. A steel tank is of enormous benifit to me and I've always
gotten to the surface fine BC or no BC. Also, because of what I have learned during
rescues, I have learned not to drop a weight belt if weights can be dropped off it.
This would be another solution to that problem.
As for your point about looking at a buddies console, I just find it convenient,
especially with a newbie. Then I don't have to care what systemn they were taught.
As for your last point
>> I'd add that doubles are back mounted when needed and/or used and as such are
>> already behind the slip stream,
This is a perfect example of what I critisize DIR for. Statements like that. You
are trying to tell me, with correct spelling, that doubles produce less drag than
a console blah de da de blah... That's silly. Oh, they're in your slipstream. Not a
chance. I've owned two sets of doubles, 72's and 90's. I quit using them because of
their horrendous drag. Surge just tosses you. Both were used with and without BC.
Doubles are just huge and saying they are in the slip stream does not reduce their
drag.
If you have not slammed or caught your wrist mounted guages while in a hole,
you are reaching indifferent places than me. That also applies to the last time I
took abalone on scuba. It was Point Buchon. Otter country. That hole was so small,
even my arm didn't fit in.
The problem is that so often, we don't know what happened.
Well, I guess I still disagree with you on these points, but as you say, it is
probably good that these discussions raise conciousness about the issues. I am still
going to take the position that DIR is not optimal for the sport diver without
modification.
From an engineering standpoint, how does a console totally neuteralize the
benifits of DIR as you say it does? That is the adaptability issue where I most
strongly disagree with you.
... Glad your diving was good. Enjoy, seahunt