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From: <ScottBonis@ao*.co*>
Date: Wed, 19 Jul 2000 02:55:29 EDT
Subject: Re: Cave dive planning with scooter
To: trey@ne*.co*, cavers@cavers.com
Hi Trey,

Your advice seems eminently simple and wise.  The reasoning is 
straightforward.  You've presented two alternatives, either of which might be 
usable in specific situations.  Thank you.

I am reminded of a time earlier in my life when I had a medical problem with 
a torn tendon in one leg.  I went to several orthopedists who hemmed and 
hawed around and weren't sure of what to do; the most ridiculous was the one 
who said "well, just walk with two canes for the rest of your life, it's not 
so bad."  At the time, I was a skier, a scuba diver, fixing up a 28 unit run 
down apartment house with my wife and we were RV wagonmasters for caravans to 
Mexico in the winter and Alaska in the summer.  The advice didn't really fit 
my life style, so I kept looking further.

Finally, through several referrals, I came across one doctor who was quite 
experienced and respected.  After reviewing my records and an examination he 
said simply "You have choices A, B, and C.  Now go talk to whomever you like, 
but in the end, you will have to decide on one.  Then you go and do it."  His 
advice was simple and wise.  And his reasoning was straightforward.  I ended 
up choosing alternative C, which several of the other doctors had never even 
mentioned.  That was ten years ago and I have never been sorry.

In my former life I worked on the design of the Polaris, Apollo, Poseidon and 
Trident guidance systems and I have always been amazed at how the most 
knowledgeable people can make the answers to even complicated problems, seem 
simple.  It belies an understanding of the whole situation.  Something that 
most people never get to see.

Thank you for your time. 

Take care and safe diving,       Scott


In a message dated 7/18/00 3:24:16 AM, trey@ne*.co* writes:
<< Scott, you either leave double the amount of gas it

normally takes you to scooter ( i.e., drop safeties

for each diver at each stage drop) assuming you are

prepared to tow each other, or you merely put in the

amount of gas it takes each diver to swim, which you

will have to figure based on where you can see the

line swimming from. Obviously, the best bet is to be

able to pull across the floor, even though it is

deeper.


We have to go with the double the scootering gas

method, and pick up full safeties , leaving the

partial stages, as there is no swimming out of Leon

Sinks, but then we also have a strict towing

protocol and always tow backup scooters, and we

never toast one scooter completely, but leave enough

juice to get back to the last one we dropped if the

current  one fails.


At 85 feet, you can get pretty liberal , but if it

were me, I would invest in two more Makos.

Propulsion ( speed ) is everything in a bad

situation.



From: ScottBonis@ao*.co* <ScottBonis@ao*.co*>

To: cavers@cavers.com <cavers@cavers.com>

Date: Monday, July 17, 2000 11:30 PM

Subject: Cave dive planning with scooter



>Hi Group,

>

>I have come across a question for which I would

really appreciate some help

>from those on the list who are experienced in

planning cave dives using

>scooters.  And I believe that there are probably

some of the most

>knowledgeable scooter divers in the world on this

list.  The question deals

>with how many safety cylinders I need to stage in a

cave and how close to

>each other they need to be.

>

>For our particular situation I can give the

following information, and if in

>the future this information should change, I can

adapt the answers we

>determine here now.  I am purposely using

conservative numbers because, as I

>have said in the past, I have this wide yellow

streak running down the center

>of my back when I'm diving in an unfamiliar

overhead situation.  And

>exploring our "New Little Cave" in Belize, when

we're more than a half mile

>in, is such a situation.

>

>The following figures might be typical to use.

>

>Scooters:    (2) Oceanic Mako's running @ 2 mph

with an 80 min. burn time.

>Divers:        Both divers with RMV's of 0.6

cu.ft./min. swimming @ 0.5 mph

>and 0.4 cu.ft./min. riding

>Back tanks: Double 85's filled to 3100 psi.

yielding 200 cu.ft.

>Drop Tanks: 80 cu.ft. aluminum's pumped to 3300

psi.

>Cave:          Drops rapidly and runs fairly

horizontal @ 70 - 85 ft., lets

>say no current for now.

>Deco gas:    Oxygen tanks can easily be staged at

the cave entrance.

>

>The scooter cave dive planning rules with which I

am familiar require

>assuming both scooters die at the point of deepest

penetration, requiring a

>swimming exit.  And subsequently the dive becomes a

typical cave dive, so I

>must have enough gas for both myself and my buddy

to exit.  The planning for

>this, should it be felt that this is the correct

approach, is straightforward.

>

>But if we have staged tanks as we plan to, they

might be, say, 1,500 ft.

>apart.  And I'm interested in opinions as to how

many tanks need to be at

>each station.  I assume our planning would be such

that we could get to the

>first set of tanks with 1/2 of our back gas

remaining, but then do we need to

>have 2 or three tanks waiting?  And at each station

along the way

>subsequently, do we need 2 or three tanks?  Or has

it been found acceptable

>to consider our remaining back gas to be enough of

a safety factor in case

>there is a problem with one of the drop tanks.

(Seems reasonable to me, but

>I'm just checking.)  I feel that I can't plan on

our support divers, being

>cave students I certified about a year ago,

penetrating much deeper than 1/4

>mile into the cave.  And since this is not a

supported project, most of the

>money I can spare has gone into buying the two

Mako's, so I can't afford any

>more right now.

>

>My guess, from the GPS readings of the cenotes with

which we are familiar, is

>that we probably will not need to penetrate more

than 1.5 to 2 miles before

>we come out another entrance.  But as this is only

what I assume (which can

>easily make an ASS of U and ME), I'd like to get my

contingency planning in

>order.  I realize that the deeper penetrations, if

necessary, may necessitate

>additional planning to accommodate the scooters'

burn times.

>

>So any thoughts on planning this type of dive would

be gratefully

>appreciated.  I figure that there is probably more

experience with scooter

>usage in cave diving on this list then just about

any other place with which

>I am familiar.  Thanks a bunch for your time.

>

>Take care and safe diving,     Scott >>

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