Kevin,

I am glad that you pose this question. Unfortunately all too many people
chose to dive air in this depth range. Experience has demonstrated that this
is the most insidious range for air diving, where often fatal errors can
occur. As you are aware, it is our firm conviction that air (eanx21) is a
useless gas for any form of diving short of your swimming pool.  If you
don't have the right gas, don't dive.

 My recommmendation to you is to boost the helium as high as you can. In
fact if you have a booster pump go ahead and try diving heliox 20 and you
will be absolutely amazed at the difference in perception and
responsiveness. Furthermore you cannot believe how well you will feel after
the dive and there will be none of the fatigue which follows deep air
diving. As for the oxygen, keep the po2 in the 1.0 - 1.2 range. Boost it to
1.4 if the dive is to be short.

Our feeling is that no price is too high for one and one's team mates
safety. Your life and that of your friends are worth well more than the
several dollars saved by avoiding the complications and expense of adding
helium to the mix. The ancillary cost of some helium is inconsequential when
you counterbalance this against the consequences of a cluster.  In dark,
cold water with heavy currents there should non other choice.

Best regards,

Bill
-----Original Message-----
From: Kevin Rottner <Kevin@So*.co*>
To: Techdiver list <techdiver@aquanaut.com>
Date: Wednesday, January 27, 1999 9:32 PM
Subject: Not a troll or a trap . . .


>Dear list:
>
>Not a troll, not a trap . . . just a search for opinions.
>
>One of my favorite wrecks sits on the sand at 143 FSW. She is a Clemsen
>Class Destroyer, DD-227, eight miles off shore in the middle of a major
>shipping lane. Built in 1919 when everything aboard was made of brass and
>bronze. One of the 4 inch guns sits on the sand at 149 FSW. Water is cold,
>Southern CA cold, between 49 and 66 degrees F. Strong current only seems to
>run through the area AFTER we get on the wreck. Great dive, but . . . .
>
>The few who dive her, do it on air and I have dove her on air, and lately
>have been using EAN 25 or EAN 26. But I am beginning to rethink this.
>
>What gas would you use ?
>
>Now that I have installed a compressor and O2 and Helium aboard my dive
>boat, I'm wondering what you trimix guys would use ?? I was thinking 25%
02,
>20%  to 40 %He, balance N2 ???
>
>I normally do two dives on her in the morning, rather than one long one, in
>order to reduce the deco obligation.
>
>Suggestions and opinions please !
>
>Kevin
>
>
>
>
>
>
>
>
>
>
>
>
>"Don't forget your history,
> Know your destiny,
> In the abundance of water,
> The fool is thirsty."
>
>Robert Nesta Marley
>
>                             [\]
>                            |
>                            |
>^^^^^^^^^^^^^^^^^^^^^^
>                                   o           o
>                                 o           o
>                                o         o
>  _____              o      o
>  (_/\_)        o   o  o
> =( )=   oo
>
>Kevin Rottner
>Southern California SCUBA
>
>--
>Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'.
>Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
>

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