[RedTerrano]

Can you believe to what depth some people are willing to sink?

A Dubai based aviator and businessman, Captain Hamish Harding, recently set a new world record of being the first to traverse the Mariana Trench.
He, along with Victor Vescovo, achieved this phenomenal feat, in a custom built submersible, DSV Limiting Factor. Incidentally Victor holds the current world record for the deepest dive by a crewed vessel.
The descended ~11 KM in the sea, and spent 12+ hours underwater.
[News]

Captain Hamish Harding


Victor Vescovo


DSV Limiting Factor


Mariana Trench

Besides the world record, they also discovered a yet unknown species of shrimp (with spindly legs and a translucent body) which is being investigated by experts.

“The pressure down there is 1,200 times more than the standard atmospheric pressure at sea level (equivalent to the weight of 8,000 double-decker buses pushing down on the submersible),” says Harding. “These creatures survive by evolving bodies that allow the water to flow through them, to equalise the pressure. Nature cannot create a shell that is strong enough for them to withstand such pressure.”

The new(?) species of shrimp

https://www.youtube.com/watch?v=5vQDqq0kN9I

The record attempt explained

https://www.youtube.com/watch?v=8JAkS06m27E

Check out the underwater footage

[V.Narayan]

Very impressive and a real achievement especially given that this was done by a non-Govt team and that the Challengers depth has been reached only thrice before. Exploring inner space, our ocean depths, have proved to be far more challenging and hostile than outer space. The crush on the submersible's structure at Challengers Deep is an astounding 1200 atmospheres that the structure and the walls must bear. In outer space the rocket living spaces need to hold out to only 1 atmospheres! Of course the temperatures and exposure to rays & micro meteors is way greater in outer space. This has in its own way contributed to science & set 2 new records of maximum distance travelled on the ocean floor this deep down and maximum time spent at the bottom. I think, though haven't read enough to confirm, that they operated without a tether to the mother ship. That is scary, very scary. If so then this is probably a first too for a depth like this. Better still the vessel will be re-used for scientific expeditions. Personally speaking I cannot but help notice the absence of cheesy PR glitz and personal glorification. Well done Mr. Harding.

[RedTerrano]

Originally Posted by V.Narayan

The crush on the submersible's structure at Challengers Deep is an astounding 1200 atmospheres that the structure and the walls must bear.

Indeed. Even I was trying to imagine a thousand G. The pressure must be absolutely crushing.
I wondered how they solved the problem. Structurally is one obvious solution. But then there is no mention of any use of exotic materials like carbon fibre.

Anyway, as a automobile enthusiast, I hope, new achievements in this sector if any, also find use in vehicle safety.

[V.Narayan]

Originally Posted by RedTerrano

Indeed. Even I was trying to imagine a thousand G. The pressure must be absolutely crushing.
I wondered how they solved the problem. Structurally is one obvious solution. But then there is no mention of any use of exotic materials like carbon fibre.

Anyway, as a automobile enthusiast, I hope, new achievements in this sector if any, also find use in vehicle safety.

Titanium is the preferred material - strong & light. I do not know what material the crew pressure hull of the Trieste (1960) was made of. Maybe high grade steel. Its walls were 5 inches thick. You have a point on carbon fibre. The viewing glass holes on the Trieste were made of acrylic glass.

For the interest of readers photo below of the Trieste bathyscape that made the first dive to the bottom of challengers deep in 1960 and Don Walsh (US Navy) & Jacques Picard (French inventor of the Trieste) in the cramped crew chamber during that dive. Walsh is still with us at age 90.

[wildsdi5530]

Originally Posted by V.Narayan

they operated without a tether to the mother ship.

How can you have a 11 km long tether? Will the tether itself not weigh a few hundred tonnes?

[V.Narayan]

Originally Posted by wildsdi5530

How can you have a 11 km long tether? Will the tether itself not weigh a few hundred tonnes?

Yes a tether, made of say high strength steel alloy of 4 inch diameter and 11,000 metres in length could weigh 700 tonnes or so. For a mother ship that may displace, for discussion purposes, between 4000 to 8000 tonnes this is not an unusual payload to carry. Almost all unmanned submersibles are tethered not only for safe recovery {if locomotive ability fail} but to also serve as a wire conduit for computer control, TV monitoring, transmitting back sonar recordings etc. Manned submersibles are routinely used in the areas of oil & gas exploration, marine biology or military purposes and typically operate down to 3000 metres. A few go to 5000 meters. Most are tethered. In their case the tether may, depending on the depth also carry a pipe for emergency air supply. Though once you are below 700 or 800 metres underwater this is not practical. Untethered manned vessels such as the one in this thread exist but are rarer. Deep Sea Rescue Vessels, operated by leading Navies for evacuating downed submariners, by nature are untethered.

I wonder why you ask "How can you have a 11 kms long tether?" - is there some engineering reason why that is not possible that you know of? I am always pleased to learn. Telecom cable laying ships carry and lay out single continuous unbroken cables 4000 kms long at the bottom of the sea bed. And this was being done well over 150 years ago. Even today's lighter fibre optic cables weigh 1.4 tonnes per kms and a ship could be carrying 6000 or more tonnes of cable to be laid on a single voyage.

[wildsdi5530]

Originally Posted by V.Narayan

is there some engineering reason why that is not possible that you know of?

Am no expert at all sir. Just trying to learn from someone whose posts I find very informative.

My doubt was not about the mothership, but the tiny submersible. It would need to be very powerful to trail a 700 tonne tether.

As for laying cables, the free end is on the earth and doesn't have to move.

Forgive me if the question is stupid.

[V.Narayan]

Originally Posted by wildsdi5530

Am no expert at all sir. Just trying to learn from someone whose posts I find very informative.
My doubt was not about the mothership, but the tiny submersible. It would need to be very powerful to trail a 700 tonne tether.

Very good point. I see you are a Doctor.

A tethered submersible is used only to map/search a limited piece of topography of the sea bed at most 500 to 800 meters diameter from the mother ship. I am no expert and others who are could write in but these tether cables are also partially or fully neutral in buoyancy thereby eliminating at least the weight part of their drag effect. The patch of the seabed or wreck or whatever that needs deeper examination has already being pinpointed by other sonar devices on board ships and the submersible is sent for the final detailed tick and tally.

As for laying cables, the free end is on the earth and doesn't have to move. Forgive me if the question is stupid.

The point I was making was the enormous length of cable ships can carry. No question seeking knowledge is stupid.

[mmxylorider]

From what I've been told, these tethers or lifelines are coated with a high buoyant material that does not weigh much on land but provides the much required benefit in water. Even an outer hollow casing would help - but experts can chime in with facts.

[kkunal.shah]

Remarkable achievement, esp after the massive PR push by Richard Barnson.

Just a few days back I got hooked to a documentary on the challenger deep after it hit my YouTube recommendations.

We’ve still not explored the deep sea & a lot of species remain to be discovered.

https://youtu.be/VoEVezcE0k0

[PJ1987]

It still amazes me that how little we know about our own planet than our neighboring ones. Anyway a great effort by the team. Sad they didn't get anywhere near the publicity of the uber famous space tourists.

[v1p3r]

Very impressive achievement, and thank you RedTerrano and Team BHP for bringing this up. It's a real pity this hasn't shown up in the news.

Originally Posted by V.Narayan

Titanium is the preferred material - strong & light. I do not know what material the crew pressure hull of the Trieste (1960) was made of. Maybe high grade steel. Its walls were 5 inches thick. You have a point on carbon fibre. The viewing glass holes on the Trieste were made of acrylic glass.

Titanium it is. The pilot/passenger compartment is an almost perfect sphere, which helps - source https://fivedeeps.com/home/technology/sub/. I would not think CFRP (to give it the right name) is a good fit here. CF tends to have high specific tensile strength but is quite weak in compression, and brittle as well. I would be hesitant to trust CF in any environment that requires compression, or structural integrity coupled with necessary flexion. My caveat is that my experience building high performance CFRP is nearly half a decade out of date now, and was limited to land-based use.

Originally Posted by V.Narayan

For the interest of readers photo below of the Trieste bathyscape that made the first dive to the bottom of challengers deep in 1960 and Don Walsh (US Navy) & Jacques Picard (French inventor of the Trieste) in the cramped crew chamber during that dive. Walsh is still with us at age 90.

I've had the pleasure of meeting and being somewhat associated with Jacques Piccard's son, Bertrand. They're an incredible family of explorers. Fun facts - Jacques' father Auguste was the inspiration for Cuthbert Calculus from the Tintin comics, and Auguste and his brother Jean were the inspiration for Capt. Jean-Luc Picard in Star Trek: The Next Generation.