Titanic tourist sub goes missing sparking search

[Akimbo]

The viewport would have been blown out if the hull failed. It was made to withstand external pressure, not internal

Off the top of my head, I would think that the end-bell/hatch would have blown off before the viewport blew out, but the shock wave and near instantaneous steam blast can do strange things. For those that haven't followed the physics of implosions, they typically occur in milliseconds. The hyper-rapid compression of the gas flashes to steam due to the "heat of compression" or Charles' Law.

Even though the carbon fiber hull is the most suspect, the viewport itself is a close second. There were many complaints and warnings from experienced engineers that the port was not rated for that depth using conventional acrylic viewport calculations. Here is a diagram of a typical submersible viewport from the O-rings for Divers thread:

Sectional view of a conical Acrylic pressure-seating viewport for a deep submersible rated for 1,000 M or 3,281' working depth. Similar ports are used for decompression chambers. The O-Ring only functions at very shallow depths, enough for the pressure to create a metal to plastic seal. ​

 

[plaamook]

Something creepy about trusting an o ring in that situation. Wow.

 

[Lorenzoid]

Something creepy about trusting an o ring in that situation. Wow.

That was my first thought when I saw the o-ring in the diagram, but the text underneath clarifies that it only operates as a seal when the submersible is at shallow depths, and a more substantial seal is made between the viewport and the hull at high pressure.

 

[lermontov]

i guess the pressure of the plug effect on the window might push the housing apart or if to moved put an disproportionate stress on one side

 

[Dan]

That was my first thought when I saw the o-ring in the diagram, but the text underneath clarifies that it only operates as a seal when the submersible is at shallow depths, and a more substantial seal is made between the viewport and the hull at high pressure.

At high pressure, the tapered surface would be the seal face.

 

[Akimbo]

Something creepy about trusting an o ring in that situation. Wow.

@Lorenzoid explained the viewport design but remember that O-rings seal all the penetrators and main hatch. The main hatch is pressure-seated but is unlikely to form a reliable metal-metal seat unless thick and conical like most of the extremely deep submersibles — as-in 6,000m/20,000'+.

The electrical penetrators are not pressure seated (in terms of O-ring design) and depend on a piston or face seal secured by threads. I have seen very large high-pin pressure-seated connectors with a bolt-flange arrangement but not for decades.

Very high pressure connectors are made by machining a metal (typically a stainless or titanium alloy) body and very precise stepped holes are drilled for each electrical pin. Gold plated pins, usually the same material as the body, are dipped in liquid nitrogen to cool/shrink. The connector body is heated to pretty high temperatures (but not enough to deform) and the glass tubes are inserted in the holes and the pins inserted in the glass tubes. Everything equalizes to room temperature to make a hermetic seal — the body shrinks squeezing the glass and pin so tight it makes a pressure tight seal. Glass has incredibly high compressive strength. There are no O-rings on the pins, just the connector body.

 

[Dan]

I thought it was only 13 prior Titanic dives, not counting shallow test dives in Puget Sound and deep dives in the Bahamas. Were there 10 test dives?

In Stockton Rush interview by David Pouge of CBS, he mentioned it made 6 dives to the Titanic in 2021 and 7 in 2022.

A second Titanic tragedy: The failure of OceanGate's Titan

David Pogue, who rode in the same underwater vehicle that perished last week, looks back on the controversial submersible, and his conversations with the man who built it.

www.cbsnews.com

Also from Titan submersible implosion - Wikipedia

"Dives to the Titanic​

Titan dives to Titanic took place during multi-day excursions organized by OceanGate. According to reporter David Pogue, OceanGate did five Titanic excursions during the summer of 2021 and five excursions during the summer of 2022.[33]

Passengers would sail to and from the wreckage site aboard a support ship and spend approximately five days in the ocean above the Titanic wreckage site. Two dives were usually attempted during each excursion, though dives were often cancelled or aborted due to weather or technical malfunctions.[33] Titan made its first dive to the Titanic in July 2021.[34] According to Rush OceanGate completed a total of 13 dives to the Titanic: six in 2021 and seven in 2022.[35] In June 2023 CBS news reported that OceanGate had a total of 12 successful dives to Titanic in 2021 and 2022.[36]"


This 2023 fatal dive is dive # 14 (2023 Mission V), according to the following article:

How many expeditions did OceanGate submersible make to see Titanic? When were they?

The Titan tragedy came some two years after the OceanGate submersible had made its first visit to the wreckage of the Titanic, on the Atlantic seafloor.

en.as.com

 

[Dan]

Some learning points from the fatal dive:

 

[chillyinCanada]

Some learning points from the fatal dive:

Good find and share. Thanks Dan.

 

[chillyinCanada]

This is Jake's (YouTube Channel DALLMYD) exclusive footage of his trip to ride Titan Mission III, few days before the fatal Mission V trip to the Titanic wreck. His description of the video: "In this video I share my personal experience with OceanGate Expeditions during Mission III, 2023 My condolences goes out to the people who passed away and their family members."

This is already posted up-thread.