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Mechanical Safety
Precautions
Scooter Dive
Planning
Towing a Diver
Mechanical Safety
Precautions
- Do not get any kind of solvent or hydrocarbon vapor
anywhere near the open scooter because it sinks into the motor compartment and
ignites when you start the motor.
- Be careful not to get propellants from spray cans near
the motor compartment.
- Leave the nose O-ring out when not in use to reduce risk
of hydrogen buildup if the batteries offgas.
- Do not put the nose O-ring in within an hour after
charging the batteries.
- When you get out of the water, take out the nose O-ring.
- Do not spray any conductive lubricant into the
motor.
Scooter Dive Planning
First of all, it is imperative that you know your scooter's burn time with the gear you are using.
You must burn test the batteries on an regular basis to be sure you can depend
on this. I calculate my burn times based on full cave gear, stages, towed
DPV's, dry suit and full prop pitch when stating burn times.
You never
want to run one DPV to its max. The best bet is to run one scooter for about
40% of its burn time and then switch to the next scooter on the way in, reverse
the procedure on the way out. This way you always have something that will get
you back to your last scooter. You do not want a situation where you have one
scooter with depleted batteries and another that has a full charge but then
breaks blades or otherwise gets messed up. Want to go further? Get more
scooters, take more gas.
Beyond short dives we require dive teams to
tow scooters in the WKPP. Three-man teams can tow one for a moderate dive,
two-man teams must tow two, and long dives must have full coverage. The number
of scooters needed for a dive can be figured using the 40% guideline.
Gas management for scooter diving is not a function of whether you can swim
out, except in rare cases of high outflow, shallow springs, where your ingoing
scooter gas will likely equal your outgoing swim gas. Scooter gas management is
a function of common sense. You will not swim out of a 300 foot deep syphon,
like some that we dive, or a 300 foot deep non flowing cave, or 300 feet of
anything. The correct way to handle this is to breathe only the stages, saving
the backgas for emergencies, and to place safety bottles in the cave at the
same intervals as stages. You must assume that with everything going wrong and
towing with no primary lights, you will take twice as long to get out so you
will need twice the gas. For instance, on light failures, you will have to be
on the line and moving more slowly. If the line is on the floor and you rode
the ceiling going in, then you will need much more gas. If you have one
problem, expect several more. DIR is designed to prevent, anticipate and or
handle anything that gets thrown at you. When, not if, you
have a problem scooter diving, you will either learn why I am so insistent on
following Rule Number One, or you will die finding out how right I am.
We dive 1/2 plus the amount of gas needed during a bottle switch on our stages,
usually 1/2 plus 300. We deduct 300 from our starting gas due to the fact that
you will not drain that last 300 without using the purge button in real deep
water. If the bottle has 3300 in it to start with, you consider it to have 3000
"effective", so the halfway mark is 1800, and adding the 300 for switching, you
would then only go to 2100 before dropping the bottle.
On the way out,
you either switch bottles with each stage recovery, or be sure you are
proficient enough to switch without stopping if you keep breathing a bottle
past the next pickup on the way out (only done if there is excess gas in the
bottle relative to the depth of the water). Usually, this is not a good idea
since you will not get enough additional time to make up for the Charlie
Foxtrot you will cause if something goes wrong that needs your attention in the
middle of an on-the-fly switch. Play it by the book. NEVER pass through a
difficult area on a stage bottle that is in any danger of running out, go to
back gas. That means most of the time go to back gas.
Partially full
stages do you no good in an emergency. The intent of proper planning is to use
the whole bottle and save the backgas. If you have to run for it, you ditch the
stages and run slick. If you are behind the curve on stages, pick up a full
safety and drop the partial stage (unless you can tow it without slowing the
team down). If one guy picks up, all must pick up unless the reason for pick up
is isolated to a one man bottle problem and not an overall delay.
Towing a Diver
The correct procedure for towing a diver is for
the towed diver to store his own DPV behind him above his legs by the tow leash
clipped to his front crotch d-ring, and for himself to hold the crotch strap of
the towing diver. He must keep his head down and leave the driving to the front
diver. If there is some other emergency, leave the dead DPV and go get it
later.
In the event of a gas-sharing situation, NEVER leave a working
DPV to go to a towing position. ALWAYS keep the good DPV with you. Let the out
of gas diver do the driving - it will keep his mind occupied and will prevent
his gas source from getting away from him.
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