Titanic tourist sub goes missing

[AZRedhawk44]

And now we have this

No it wouldn't have dove like an arrow if it lost propulsion. A sub isn't an airplane

Not an airplane, but could be an aquaplane/hydroplane.  If it is negatively bouyant, it will sink.  If it is sinking, it will do so in an orientation that places the center of mass to offer the least resistance during free fall.  A badminton shuttlecock falls ball first.  An arrow falls tip first.  This is due to the center of balance being forward of the geometric center of the object, and the rear of the object offering drag.  Variation from point-first-flight of these two objects results in the vanes producing even more drag.  The objects fall in the most efficient orientation possible.

I suppose the sub could fall nose first if the ballast was too far forward towards the nose hatch, and the passengers were all crowded towards the nose, and power was lost.  Look at the design of Deepsea Challenger.  That vehicle is a vertical pill design rather than a horizontal pill design like Titan.  It naturally fell vertically.  All it would take to mimic the descent profile of that vehicle is a change in center of mass.

[dogmush]

Remember though that boats (and submersibles) have a Center of Buoyancy, which is not the same as the CG.  The distance between the CG and the CB creates a righting force proportional to that distance.  This is what keeps boats upright on the surface, and is the main part of submarine attitude control.  Drag through the water at the speeds  it was probably sinking is not very significant.  (unless it had already popped and the wreckage was several tons negatively buoyant.  Than it would sink pretty quick.)

[RoadKingLarry]

I'm not sure why he thinks the CG or CB would change appreciably if the thrusters cut out.

My guess is that he is a freaking moron with delusions of adequacy.

[Hawkmoon]

I'm not sure why he thinks the CG or CB would change appreciably if the thrusters cut out.

Or why the ballast weights wouldn't have fallen off if the capsule went into the nose-down orientation.

[WLJ]

I seriously wonder if the mothership even had the capability to haul the sub on deck which brings back concerns I had about opening the hatch (17 bolts) while the sub was still in the water and unable to get on the towed platform.

The Alvin research sub is transported to dive sites on the deck of a dedicated mothership, which is outfitted with custom winches and a large crane that places it in the ocean.

In contrast, Titan had no dedicated mothership, and to cut costs it was towed out to sea on the fatal dive by a smaller chartered vessel, the Polar Prince.

The Polar Prince, a decommissioned Canadian Coast Guard icebreaker, was smaller and older than the ships OceanGate had used in previous years, in a cost-cutting move by Rush.

Using a tow cable, the ship dragged the Titan across hundreds of miles of open sea on top of the launch platform that was used to submerge and retrieve the sub.

Disturbing new theory on why Titan imploded: Experts slam CEO for hiring cheaper 'mothership' which dragged shoddy sub across rough seas to Titanic site, unlike safe rival that's kept on deck
https://www.dailymail.co.uk/news/article-12303359/OceanGate-CEOs-cost-cutting-measures-doomed-Titan.html

[Hawkmoon]

I doubt the towing would have contributed to the implosion of the hull, but the entire operation shows that the CEO was basically a cheap *expletive deleted*it who wasn't interested in maintaining generally-accepted factors of safety.

[WLJ]

I doubt the towing would have contributed to the implosion of the hull, but the entire operation shows that the CEO was basically a cheap *expletive deleted*it who wasn't interested in maintaining generally-accepted factors of safety.

I doubt that too, my concern is whether or not the mothership had the capability to haul the sub aboard if need be. If not there's no way they could have removed all 17 bolts and got them out before the sub flooded if it was still in the water.

[cordex]

I doubt that too, my concern is whether or not the mothership had the capability to haul the sub aboard if need be. If not there's no way they could have removed all 17 bolts and got them out before the sub flooded if it was still in the water.

What was the plan to recover them if something hadn’t gone wrong?  They must have had some way of loading and unloading people at sea.

[WLJ]

What was the plan to recover them if something hadn’t gone wrong?  They must have had some way of loading and unloading people at sea.

The sub was suppose to maneuver to the platform while still underwater and then the platform would raise it to the surface.
Whether or not the platform itself could maneuver on it's own under the sub if the sub lost power or maneuverability I don't know as I haven't seen it stated one way or the other. Could the mothership haul it up out of the water? One would hope it could but with this guy?

The Alvin research sub is transported to dive sites on the deck of a dedicated mothership, which is outfitted with custom winches and a large crane that places it in the ocean.

In contrast, Titan had no dedicated mothership, and to cut costs it was towed out to sea on the fatal dive by a smaller chartered vessel, the Polar Prince.

The Polar Prince, a decommissioned Canadian Coast Guard icebreaker, was smaller and older than the ships OceanGate had used in previous years, in a cost-cutting move by Rush.

Using a tow cable, the ship dragged the Titan across hundreds of miles of open sea on top of the launch platform that was used to submerge and retrieve the sub.

[WLJ]

Beware of discount Titanic wreck tour tickets

[WLJ]

Found a photo of the Titan being hauled up onto it's mothership while on it's platform on a previous expedition but as stated in the above article and evidenced by photos Rush ditched that mothership for a cheaper one that had to tow the platform.

https://www.prestigeonline.com/sg/people/events/passengers-on-titan-titanic-submersible-dead/

[dogmush]

We discussed this a bit a few pages back. Polar Prince has a pretty decent davitt on her gargo deck, that appears to be capable of moving 20ft connexs around.  The max weight of a 20ft box is like 52,000 lbs so plenty of grunt for the Titan.

Even if they couldn't lift the sub on deck, they could rig the lift and hold her at the surface while a swimmer popped the bolts and got the passengers put in an emergency.

Not making excuses for Rush's lack of planning,  but this particular piece of catastrophising is probably not an issue.

[WLJ]

We discussed this a bit a few pages back. Polar Prince has a pretty decent davitt on her gargo deck, that appears to be capable of moving 20ft connexs around.  The max weight of a 20ft box is like 52,000 lbs so plenty of grunt for the Titan.

Even if they couldn't lift the sub on deck, they could rig the lift and hold her at the surface while a swimmer popped the bolts and got the passengers put in an emergency.

Not making excuses for Rush's lack of planning,  but this particular piece of catastrophising is probably not an issue.

Saw that in photos but was unsure if was still on board since all the photos I had seen previously showed her with it was while she was still painted in her coast guard colors. Apparently she was painted blue over the coast guard red in Oceangate service. All those photos I had seen previously after being painted blue where at the wrong angle or were too blurry

Guess it's still there

[WLJ]

Why mess with this whole platform business then? Seems like on the surface (unintended pun) using the platform system would greatly complicate both the journey to and from the wreck site and the process once there rather than just lift it down then back up on board instead.

[dogmush]

Dunno.  Maybe the designer of this sub wasn't that good. 

I note that the platform was part of the design even when they had a mothership that could get Titan on deck easily.

[WLJ]

Dunno.  Maybe the designer of this sub wasn't that good. 

I don't know what would have given you that idea

[cordex]

Is lifting a vehicle via crane with occupants a standard, acceptable technique?  Seems like that could be a safety concern in and of itself.

Might be a good thing to plan for in an emergency, but maybe there was a good reason for that additional step and cost.

[WLJ]

Is lifting a vehicle via crane with occupants a standard, acceptable technique?  Seems like that could be a safety concern in and of itself.

Might be a good thing to plan for in an emergency, but maybe there was a good reason for that additional step and cost.

Far as I'm aware they've been doing it that way with submersibles for decades.
If the sub can't withstand being lifted up on deck I ain't riding in it.

[dogmush]

Is lifting a vehicle via crane with occupants a standard, acceptable technique?  Seems like that could be a safety concern in and of itself.

Might be a good thing to plan for in an emergency, but maybe there was a good reason for that additional step and cost.

Lifting people with cranes is common.  Man baskets, inside secured loads, as long as the people being lifted have something to keep them from falling out it's a generally accepted practice.

[dogmush]

Some interesting pics of the building process in this video, as well as video from the MV Polar Prince on a previous trip.

https://www.youtube.com/watch?v=Gm28gju5Brw

[WLJ]

Some interesting pics of the building process in this video, as well as video from the MV Polar Prince on a previous trip.

https://www.youtube.com/watch?v=Gm28gju5Brw

Saw that this morning. He noted the viewport as far as we know has not been recovered.

[230RN]

Two cents: Probably shattered in a dozen pieces, falling for a long distance, well scattered, and probaly also opticallly invisible.  (That's another two cents.)

Best hurry-up guesses of refractive indices:

Seawater 1.33-1.34 best guess

Teflon ("plastics?") 1.315

These numbers vary a bit depending on a lot of things like light frequency, temperature, blah-blah-blah, but you can see that even with the port still in one piece,  it would be hard to detect.

I should be charging five cents for that.

Sort of like looking at one of those "puree" marbles in a glass of water.  (For those of us who used to shoot marbles.)

Terry, 230RN

[JTHunter]

Lifting people with cranes is common.  Man baskets, inside secured loads, as long as the people being lifted have something to keep them from falling out it's a generally accepted practice.

Have you ever seen the Hoya Lifts they use in hospitals and nursing homes?  It works in much the way as a lift for a car's engine.
If this "sub" was incapable of being lifted in similar fashion - - - . 

[Hawkmoon]

Have you ever seen the Hoya Lifts they use in hospitals and nursing homes?  It works in much the way as a lift for a car's engine.
If this "sub" was incapable of being lifted in similar fashion - - - . 

But, but ... it was innovative. Revolutionary, even. A paradigm for a new generation of undersea exploratory vehicles.

And the CEO actually believed his own hype ...

[dogmush]

The Titan literally had lifting slings built in.  They are in every picture of it.