Peter,
Well in this case you
have adult supervision……
Can happen the best. Once
the Dutch and German sgt. Pepper crew launched the sub with the floodvalve
open! The valve was frozen and after fixing it we forget.
Accidents never happen
alone; this dive a friend was driving it the first time…
All the best with
building Nautilus to end…. Before diving it!
Groet, Emile
Van:
owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org] Namens UC3 NAUTILUS
Verzonden: maandag 25 augustus
2008 21:33
Aan: personal_submersibles@psubs.org
Onderwerp: [PSUBS-MAILIST] A
voyage on Nautilus, and the story of the boyancy crisis...and how we almost
lost control...
Dear Psubbers,
One of the things that are quite seldom here is operational stories - what you
experience when going out with your subs. Half an hour ago Nautilus arrived at
her base with me a serious lesson richer - and here is the story...of the
boyancy crisis and how we almost lost control...
Todays voyage was to start at 1400 hours, with the crew arriving at 1300. We
intended to take a joy ride through the Copenhagen Harbor, and into the sound -
ending at our northern base. Its about 8 nautical miles and we expected to sail
for about two hours.
We had a very special crew, and a very special guest - Richard. R. is a
"very high ranking" retired US navy submariner - who at age 70
visited the Nautilus. He has had the command of several US diesel and nuclear
submarines. Also we had Daniel, a former Danish navy submarine TKO - technical
officer and one navy surface ship navigator. Ad two navy seals - off duty - and
you have a crew with quite some experience.
Nautilus performed very well, and as we passed the shipyard area where she was
build, we came ashore and visited the drydock where Kraka lies. She is
operational, but disused and awaits going to the Danish Technical Museum. All
the crew were most happy, in no small part Richard. The new coffee machine in
the gally was tested and worked well.
Into the sound we increased speed to flank. We had three person in the sail, no
fuel in the tanks ( we run her from a jerrycan ) and all tanks blown. As a
result the stability margin is marginal - al as expected. We had som osciliations
giving some 30 deg. swings as we whent flank speed, som we discussed ways to
increase stabilty. One of the questions to be asked is if the free uncontroled
water surface in the main tanks will make the boat more unstable than the
potential stabilicing effect of the boat deaper in the water. To test this we
came to stop, and manually wented air from the fwd and rear main ballast tanks.
The boat is not finished. There are no blowing tubes or valves inside, but form
outside - via a hose you can blow the tanks. Also the diving valves at this
stage can only be operated from outside.
The fwd. valve was opened, and this tank floded about 50 %. The rear tank was
opened, and it floded about 50 %. Nautilus was lying at a deep trim - her fwd
hatch closed, and with a free board of about 2 meters to the sail
hatch. Aparently stable...
Then one of the deck crew reports - "Sir, - we are still sinking in the
stern" And yes - the rear diveplane was now slowly submerging...ok - I go
check the valve, its closed and tight...but we are still sinking slowly...water
begins covering the rear deck...
I gues I build submarines in part to feal that thrill...Ups...did we mis a step
here ?...like mission control in Houston you start to figure out - what in the
hell is going on - while staying calm. You try to be in advance of the
situation - How deep will we except this to go - what actions need to be taken
- how much boyancy do we have in the sail - what is the mechanisem behind
this...
Then mr. Madsen, Master and Comander of his home made submarine flotilla -
realises that the rear trim tank - enourmours at some 1.5 m3, is floding
uncontroled due to a flange remowed ( to mount the new tube. )
Frankly - at this point I did not know when this was going to be stable. We
could have ended up much like the U-505 ( se pic from her US navy capture )
with only the top of the sail and the bow above water. If so, I would have
ordered the sail hatch closed - engine shut down and the crew out of the
engineroom and on deck. Likely our fwd hatch would never have gone under since
most of the bouyancy in the bow was still there. At the end - with both hatches
closed the boat would stay surfaced a some angle, but holy shit, how stupid can
a man be ?
As it was Nautilus stabiliced with the water just below the deck level, and
with the bow at about normal trim. No problem at all, Kraka has lived her life
like that - but this was not because of my talent or smartness, no - just
simple luck.
Carsten and his Germans will now tell me how stupid I am - and I agree. I for
my part told Richard the story of the Seydlitz, a German WWI battlecruiser
returning to port after the Battle of Jutland with all of the fore deck under
water...only to be repaired and returned to service...and scuttled at Scarpa.
The good thing about it was that everybody was calm and working together to
finde the cause - and we quickly did - and then we continued at slow first.
Indeed with her tanks part floded Nautilus was far more stable, and we
increased to flank speed while seeing the bow raising under the hydrodynamic
force of the rear planes. ( so are we going to sink when we slow down ?! )
We did not - we got fine to port, blew the tanks, and there she is safe and
sound.
Richard, our navy comander - gave me a US Navy officers badge, and said a lot
of nice things - that I really fell I don´t deserve after this ordeal that was
all my fault - but I have decided to learn from it. Not so much in the detail -
since its a specialty - that we will never see again, but as a lesson in the
safe operation of big dangerous machines. I may sound stupid, but whenever you
get to the edge of what you have done before, slow down, analyse carefully
before taking the next sted. I failed to do so - because of the exelent way the
boat and crew was performing in other irralevant ways.
The missing part for that flange cost about 2 US doller.
Have a nice day - and don´t play with water with out adult attention...
Best regards,
Peter
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