[PSUBS-MAILIST] deep test

Fri Jan 26 12:38:39 EST 2018

Hank, I have not worked the details yet but I can give you my tentative
thoughts.  The location of the test will be Lake Tahoe in Ca on June 25-29,
2018 as you know, with Homewood Ca. as the base.  We will use a tender
vessel that will setup over the dive site.  We will find a dive site with a
bottom at a little past my max test depth of 375 ft.  I plan on ballasting
up the boat so that when the MBT are flooded, the boat is about 20 lbs
positive.  I will then attach a 400 ft line that has been marked every 10ft
 to the bow lifting lug. When we are ready to do the test and you are ready
to submerge Gamma, I will add 25 lbs of lead ballast wrapped up in rubber
so it will not damage the boat on a line just aft of the viewport.  This
location is just above the CG/CB of the boat.  Boat crew will slowly lower
the boat until reaches the first depth station at 75 ft. We will stay on
station for 5 minutes.  At any point if the bow line starts to add weight,
we will abort the test and pull the boat up immediately. Divers will be in
water and follow boat to  75ft stop. Gamma will be monitoring the dive all
the way and down and back up.  Also, if Craig Busell can make this date,
his Phantom T4 ROV will also be monitoring/logging the dive and giving us
real time video feed on the surface which would be great.  The boat will
then be lowered in 20% of test depth increments (75ft).  At each depth stop
we will stay on station for 5 minutes.  If all looks good we will proceed
to the maximum test depth of 375ft where we will stay for 30 minutes. We
will then pull the 20 lb weight off the boat which should change the boat
into a positive buoyant state.  Gamma and the Phantom will monitor the
decent and ascent.  As a back up, the PLC on the boat will be programmed to
automatically blow MBT at 2 hours from the start of the dive.  The PLC on
the R300 will have logging turned on so at the end of the dive I can
retrieve the memory card to interrogate all boat systems during the test
dive.  I will look into a number of backup steps including seeing if
a local dive shop has a diver with a rebreather that would be willing to
dive to 375 ft.  We will make sure we have some kind of harness on the bow
lifting lug that gamma can attach to in case we need her to lift the boat.
If the boat floods, the weight will be 4400 lbs in the water so will need
to see if can  locate a lifting bag large enough to lift the boat in a
salvage mode.  We would not bring the lifting bag to the site but just know
where to get one if the test fails.  The maximum depth the boat has been to
is 160 ft last year.  If the unmanned test is successful, and surface
inspection reveals no surprises, then I will take the boat down to 300 ft
to establish the maximum operating depth of the boat.

For those of you that have gone through this type of unmanned test before,
I would welcome feedback. What worked for you and what you would do
differently.  I can't remember which boat but I remember one psub unmanned
test dive using a similar methodology in which the two line got wrapped up
and fowled. Alec, was this you with Snoopy?  I don't remember how they
recovered.  I remember the test was successful.  I am not to worried about
the test as the crush depth is 1100 ft (in theory!)

Still lots of details to sort out.

I know you tested Elementary 300 pressure hull in a pressure vessel but
have you done the unmanned test on her?  Also after rebuilding Nekton
Gamma, have you done an unmanned test of her?  If so how did you do it?

Cliff

On Thu, Jan 25, 2018 at 6:40 PM, hank pronk via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> Cliff,
> How are you planning to lower R-300 and how are you retrieving it?
> Hank
>
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