Author Topic: Starship Ocean Platform; Advantages and Difficulties  (Read 34456 times)

Offline JoerTex

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #60 on: 01/08/2021 05:30 pm »
For this discussion, I think some data on seafloor depth would be useful. As far as I can find, the seafloor has a very small slope and is still only about 50 meters deep 50 km out to sea from Boca Chica.
https://woodshole.er.usgs.gov/project-pages/mobility/images/gmex.png
https://charts.noaa.gov/PDFs/11301.pdf

Would this not make tunnels a viable option, particularly given Elon being a fan of them. Either a Boring Company tunnel, or a prefabricated tunnel laid down on the seabed (like the Tansbay Tube for the BART).

Bridges are possible, but I would assume much more troublesome to build. An example that springs to mind is the Řresund Bridge, linking Denmark and Sweden:
https://en.wikipedia.org/wiki/%C3%98resund_Bridge

Also, given such small depths, why would any platform be floating, rather than directly fixed on the seafloor?

Agree heartily. At these shallow depths fixed seafloor platforms are the simpler solution.
Long bridges block access and environmental political review would take ages and most likely fail review.
Anyone know what the feature ~12 miles offshore on the noaa chart near he Mexican ocean border labeled (2) is? 
Could is be a shallow seamount? Size?

Google Earth gives a discussion quality map of depths in the gulf.  It's not particularly deep 25 miles out from shore.

Offline sghill

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #61 on: 01/08/2021 06:15 pm »
Also, We can put some boundaries on just how far off-shore a Gulf of Mexico-based point-to-point launch operations platform can be in order to remain competitive with air travel.

And I will repeat, there is no point to point Starship travel without overflights permitted. None.

First, let's make four assumptions:

1) Only the total trip time matters for this exercise. Leaving one City and Arriving in another.
2) The cost and/or priority need for this exercise is not an obstacle.
3) We are assuming one launch site from the US for this exercise in the Gulf of Mexico.
4) None of this particularly matters for orbital or BEO space launches.

In other words, we are looking at an apples to apples comparison of how long it will take a passenger to leave their home city and arrive at their destination city.

Using Net Present Value thinking, if the travel time time for Starship is one minute longer than the conventional jet travel time, there is no business case.  Why am I bringing this up? Because it is exactly the same economic problem that killed Concorde flights. They were fast and expensive flights, but they were so rare between flights that you could have arrived at your destination on the next 747 flight long before Concorde even left London for New York on its twice daily flight- irrespective of that cost and speed. Anyway, back to Starship...

We need a formula for comparison to give us the Max distance off-shore the launch operations can function while retaining the value proposition favorable for point to point travel. We need to identify the common elements and the variable values.

Now, I am ignoring cargo and disembarking times at the final destination, and I am also ignoring any non-direct airline flights because for this exercise they don't matter. They are either shared or they don't matter.  Also, I am ignoring cities where the hub and spoke means of travel come into play because no one flies from Fayetteville to New York City to THEN get on a Concorde to London. Let's just look at the cities where the travel time by airliner would be the shortest and also the likelihood of travel to the destination city by a traveler with the means and need for Starship travel is greatest.

So what we need is the SUM of all Starship's variables to be less than the sum of the jet airliner's variables for the business case to work.

What the table below shows is that there are lots of elements of Starship travel that are unavoidable (unless you ALREADY happen to live in Houston and want to fly to Tokyo on Starship). What is variable is the length of time it takes to get out to the Starship launch platform, and also the cargo and passenger handling time on the ground.

Starship Variables:   Values in hours
A) Boarding and loading time in origin city (LA or New York) to departure city (private flight to Galveston)    0.5
B) Flight time from origin city to Galveston (private direct flight).   4
C) Transfer and Pre-Boarding time for flight out to the to Launch Platform   1
D) Surface or air transport travel time out to Launch Platform   0.5
E) Cargo Loading and Pre-boarding time for Starship (Also making the assumption that fueling has already occurred, or is occurring simultaneously)   1
F) Starship launch and flight time   0.25
G) Disembarking and cargo unloading at landing platform   1
H) Surface or air transport travel time away from landing platform to receiving city (London, Tokyo, or Seoul)   0.5
Total Travel Time:   8.75
   
Airline Travel Variables: LA to Tokyo   
A) Boarding and loading time in origin city   3
B) N/A   
C) N/A   
D) N/A   
E) N/A   
F) Jet airliner taxi and flight time   12
G) N/A   
H) N/A   
Total Travel Time:   15
   
Airline Travel Variables: NYC to London   
A) Boarding and loading time in origin city   3
B) N/A   
C) N/A   
D) N/A   
E) N/A   
F) Jet airliner taxi and flight time    7
G) N/A   
H) N/A   
Total Travel Time:   10


The lesson is, the launch platform transfer and ground handling costs enough time that Point to Point passenger flights for a passenger from the New York area to London don't make sense unless there is a launch platform accessible directly from New York- even if money is no object. They make a little more sense from LA to Tokyo. And I had my thumb heavily in Starship's favor on these scales by not using commercial airport boarding and transfer times to make the flight to Houston and then to the platform, assuming direct flights, and assuming very fast flight times in the destination city from the landing platform.

They make a lot more sense for LA to Abu Dhabi or some other ridiculously long-haul flight. Concorde could barely make the trans-Atlantic flight (it had to carry fewer passengers on the East-bound leg), so it's price premium could not meet the time cost penalty for such a short flight. Starship, on the other-hand, can cover a hemisphere. It needs lots of launch and landing platforms with super rapid transfer, but if they regularly carry enough passengers, I think there is a business model to be made here.

« Last Edit: 01/08/2021 06:18 pm by sghill »
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Offline philw1776

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #62 on: 01/08/2021 07:46 pm »
You're on the P2P Starship flow where by definition overflights aren't a problem. I'm considering this decade's possible ocean launch sites for Mars transport through the early 30s.  In this view overflights of Galveston, etc. shipping lanes and offshore platforms are likely a big issue.
I see P2P as very late 2030s at earliest but there's a separate topic for that discussion.
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Offline CameronD

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #63 on: 01/11/2021 12:31 am »
The lesson is, the launch platform transfer and ground handling costs enough time that Point to Point passenger flights for a passenger from the New York area to London don't make sense unless there is a launch platform accessible directly from New York- even if money is no object. They make a little more sense from LA to Tokyo. And I had my thumb heavily in Starship's favor on these scales by not using commercial airport boarding and transfer times to make the flight to Houston and then to the platform, assuming direct flights, and assuming very fast flight times in the destination city from the landing platform.

From what you've posed and as I see it, the key issue with ocean launch platforms doing PTP flights really has nothing at all to do with the technology - as discovered by airport planners a century ago, they simply don't make economic sense unless you happen to be living nearby.

Case in point:  One reason for the invention (and demise) of the A380 was a widely-advertised plan for a 'hub and spoke' model of global air transportation.  For many reasons, a few years back it was thought it might be more efficient (economically and time-wise especially) for people to fly from their local to a major international hub and be transported to another international hub before travelling on to their destination.  The problem here was that (a) depending upon where the hub is, it turned out that for smaller numbers of people it's actually more efficient to travel from their home town direct to their destination and (b) it seems folks don't especially like taking three flights when they can take one - which is quicker door-to-door anyway - and (c) large numbers of passengers arriving at the same time created headaches for everyone with long delays in security processing and baggage collection at both ends.

What that means is, for this proposal to be anything other than a novelty (like the A380 ultimately is) there needs to be lots of these platforms, ideally one close to each major city - but no matter how close you get by sea, you simply aren't going to be able to compete economically with the same set-up anywhere on dry land, which is always going to be both closer (quicker to get to) and cheaper and more readily accessible by road, train and air (not just expensive sea and air).  For this reason IMHO even if it can be make to work somehow, we'll see it travel the way of the A380: ie. it will take years to develop, costing a small fortune in the process; it will be a great novelty for a while; and it will, a few years after inception, be replaced by launch pads on dry land.
     
« Last Edit: 01/11/2021 12:39 am by CameronD »
With sufficient thrust, pigs fly just fine - however, this is not necessarily a good idea. It is hard to be sure where they are
going to land, and it could be dangerous sitting under them as they fly overhead.

Offline Robotbeat

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #64 on: 01/11/2021 01:13 am »
Not sure I agree with that. There are some unique aspects of rocket travel that make ocean platforms better. Arms control, mass production of very weird, custom GSE, and especially the need to be like >15 miles away from any houses.

I actually think E2E is pretty unlikely in the next several decades except for very niche payloads, and the reason is because of safety and the large footprint of rocket launching. I hope to be wrong.
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Online Zed_Noir

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #65 on: 01/11/2021 12:31 pm »
<snip>
I actually think E2E is pretty unlikely in the next several decades except for very niche payloads, and the reason is because of safety and the large footprint of rocket launching. I hope to be wrong.

The US Air Mobility Command might operated P2P Starships for movements between logistics hubs. Since that is only the way the DoD can get enough surge logistics capacity without buying a lot more air transports and aerial tankers plus ground side infrastructure expansion. Maybe even pressed all available transport variants of the Starship into service for the duration of an emergency.

Offline edzieba

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #66 on: 01/11/2021 02:15 pm »
Starship won't be flying anywhere that doesn't have an LCH4 & LOX retanking facility (or you'd never get it back). It absolutely won't be flying into anywhere that doesn't have total control of the local airspace, as it is incredibly vulnerable throughout all stages of flight, and even when landed for offloading.

Offline danneely

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #67 on: 01/11/2021 04:18 pm »
Starship won't be flying anywhere that doesn't have an LCH4 & LOX retanking facility (or you'd never get it back). It absolutely won't be flying into anywhere that doesn't have total control of the local airspace, as it is incredibly vulnerable throughout all stages of flight, and even when landed for offloading.

It'd definitely need new infrastructure, but similar constraints on airspace safety also apply to C-17/22/130 transport aircraft.  In some ways though Starship would actually be less vulnerable to hostile fire in transit.  While it's limited in there effectively only being a single flight path between any two points except at takeoff/landing it's beyond the reach of hostile fighter aircraft and conventional AA systems.  Some ABM/ASAT systems would have the reach to engage it mid-flight; but they're far less common than conventional SAMs.

Offline alastairmayer

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #68 on: 01/11/2021 04:48 pm »
<snip>
I actually think E2E is pretty unlikely in the next several decades except for very niche payloads, and the reason is because of safety and the large footprint of rocket launching. I hope to be wrong.

The US Air Mobility Command might operated P2P Starships for movements between logistics hubs. Since that is only the way the DoD can get enough surge logistics capacity without buying a lot more air transports and aerial tankers plus ground side infrastructure expansion. Maybe even pressed all available transport variants of the Starship into service for the duration of an emergency.

Another thing to consider is that SpaceX looks like a much more reliable supplier of air/space craft for a given cost than the current aircraft manufacturer incumbents.

Offline OTV Booster

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #69 on: 01/11/2021 08:16 pm »
Not sure I agree with that. There are some unique aspects of rocket travel that make ocean platforms better. Arms control, mass production of very weird, custom GSE, and especially the need to be like >15 miles away from any houses.

I actually think E2E is pretty unlikely in the next several decades except for very niche payloads, and the reason is because of safety and the large footprint of rocket launching. I hope to be wrong.
P2P for irregular and unscheduled priority cargo makes more economic sense than for passengers. Either way, ISTM that a Star Ship Light would better serve. Same construction techniques, same engines, smaller diameter. Maybe 4or 5m (guess). There are probably good engineering arguments that show a lower efficiency but the rocket is only one part of the system.


If a smaller version can use land facilities that is its own efficiency. I think there's another thread for SS variants for any who want to go into the details but exploring the impact of a variant seems fair game for this thread.
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Offline OTV Booster

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #70 on: 01/11/2021 09:12 pm »
<snip>
I actually think E2E is pretty unlikely in the next several decades except for very niche payloads, and the reason is because of safety and the large footprint of rocket launching. I hope to be wrong.

The US Air Mobility Command might operated P2P Starships for movements between logistics hubs. Since that is only the way the DoD can get enough surge logistics capacity without buying a lot more air transports and aerial tankers plus ground side infrastructure expansion. Maybe even pressed all available transport variants of the Starship into service for the duration of an emergency.
Interesting idea on the surface. It's down in the weeds that problems show up. Unless there are propellants available at the destination it'll be a one way trip. Maybe a P2P tanker? Not impossible, but if it takes 5 tankers to get one SS back I think I see a leetle problem.


A one way trip can be justified to solve a high priority problem. Something like staging an army to England to liberate Europe, assuming England can make return propellant. Then a slap bang one way jump across the channel to kick things off. Well, maybe a bigger operation than what you meant.


I've been long time fascinated by military logistics and my reading shows two modes. Push and Pull. Push is when things are pushed to the theater automatically based on the number of bellies to be filled and clothed and estimated fuel and ammo expenditure rates. Pull is when the estimates are off and you requisition laser toner that never got pushed. Think of all the little things you use every day that will not be there when a military force arrives.


In Desert Storm they used hand scanners and modern stocking procedures (with Walmart as a major adviser IIRC) and they established a priority system to fly things over expedited. The system was abused and clogged. Clogging aside, putting hands on the material, getting it to an airfield then getting it distributed after arrival took more time than the transit itself.


The troops went over by air. The tanks and other heavy equipment by ship. The initial non bulk push logistics went by air. Food was purchased on the local economy as much as possible. IIRC, the fall of the wall allowed European stocks to be transferred. Some interesting factoids: food was less than 2% of the total logistics load. Most of the rest was fuel (Saudi supplied) and ordinance. An armored division (~15k-16k troops and a butt load of iron) consumed 1200-1600 tons per day while engaged in operations. A stripped down military flatbed or tanker semi carries ~50-55 tons.
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Offline CameronD

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #71 on: 01/11/2021 10:08 pm »
Another thing to consider is that SpaceX looks like a much more reliable supplier of air/space craft for a given cost than the current aircraft manufacturer incumbents.

That's a bit harsh.. For one thing, they're in totally different markets and the current spacecraft market isn't affected by a COVID-induced downturn to quite the same extent as the aircraft market.  If Starship were flying passengers right now, maybe things would be different - but they aren't and won't be for a very long time to come.
With sufficient thrust, pigs fly just fine - however, this is not necessarily a good idea. It is hard to be sure where they are
going to land, and it could be dangerous sitting under them as they fly overhead.

Offline spacenut

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #72 on: 01/11/2021 10:41 pm »
If point to point is expensive, then for quicker times paying for a private jet flight might be just as quick.  You avoid check in time and screening at an airport which can be as much as two hours. 

My wifes son lived in Milwaukee a few years ago.  We had to drive 90 minutes to Atlanta, go through check in about 2 hours early, have a flight to Chicago for about 1.5 hours in the air, then get picked up by her son and drive another 90 minutes to where he lives.   This always was about 6-1/2 to 7 hours.  We could drive it in about 11-12 hours and that is stopping a few times for a meal, gas, and bathroom breaks.  Then we could take a load of say Christmas presents.  It would have been harder on a plane especially checking luggage or taking a chance of lost luggage.  Sometimes slower is better and many times cheaper, especially if we had to leave our car in Atlanta. 

Then using the internet and computers for business meetings, long distance business flights may never return to pre-covid levels.  I agree with many here that point to point may involve the military or special cargo more than business flights.  It all depends on cost. 

And then there is hypersonic planes people are working on.  This may be a direct competition with point to point. 

SpaceX first has to master the belly flop landings. 

Offline edzieba

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #73 on: 01/12/2021 10:34 am »
In some ways though Starship would actually be less vulnerable to hostile fire in transit.  While it's limited in there effectively only being a single flight path between any two points except at takeoff/landing it's beyond the reach of hostile fighter aircraft and conventional AA systems.  Some ABM/ASAT systems would have the reach to engage it mid-flight; but they're far less common than conventional SAMs.
Starship during the post-entry bellyflop is moving low supersonic to subsonic, in a nice straight path (with very little aerodynamic manoeuvre capability relative to aircraft), while glowing brightly in the IR regime, and with an extremely thin and delicate monocoque semiballoon construction. A single manpad would find popping a Starship trivial. It is far more vulnerable than even the ponderous C-5, and those are already restricted from some tasks due to their vulnerability.
There is also the issue that there are few adversaries who actually demand staging 100 tons of materiel to the other side of the planet within single-digit hours (rather than the tens of hours of existing airlift), that also do not have the capability to intercept high-speed vehicles at high altitudes, or even outright ABM capability.

Starship is not going to be landing in (or even flying over when possible) anything other than very friendly territory.

Offline Eka

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #74 on: 01/15/2021 08:14 am »
Kinda Off Topic: Concorde was killed by faulty maintenance, a few errors and a flight instability that was exacerbated by the fuel tank rapidly emptying. Basically, the plane was doomed because the center of gravity moved too far aft when it was going slow. The fire was survivable, the center of gravity moving too far aft was near certain doom due to the flight instability. A good article on it: https://askthepilot.com/untold-concorde-story/

On Topic: I thoroughly expect people will reschedule travel to take a Starship flight for the dimple reason of avoiding time cooped up in the air. If you haven't flown a lot you won't understand. I was a sometimes Concorde flyer when I was young. Most often for emergencies where it took longer to get one of the biz jets to me, than waiting for and taking the next Concorde flight. I loved that I could go from DC to Paris in 4 hours gate to gate, or NYC to London in 3.5 hours. People scheduled their travel to fly them to avoid 4 to 5 more hours in the air. The biz jets took 8 to 9 hours so I often flew overnight and slept the flight away. An advantage the biz jets had over Concorde was they usually went much closer to where I wanted to go.
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Offline Eka

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #75 on: 01/15/2021 09:36 am »
Someone at another site concern-trolled the idea of “marine noise pollution.” Assuming the exhaust goes straight into the water, offshore SH launches would inject enormous amounts of acoustic energy into the ocean, on a regular schedule.

Not sure what to think about that.

Curtain wall bubbles was what I heard suggested.

A ring of seabed emplaced pipes/valves/nozzles that can inject large quantities of air into the seawater. They start doing this just before ignition, with sufficient time for the bubbles to rise to the surface from the seafloor. Tne nozzles are close enough together that there is little or no pure water between bubbles

This supposedly forms a curtain wall that will attenuate soundwaves a lot.

I can't remember where I heard this or whether it's ever been done at this scale. It would take a LOT of compressed air, that's for sure!

OK NVM:
This came up in another thread some time ago and bubble curtains look like something that may work.
https://canadianpond.ca/air-bubble-curtains-bubble-tubing/?gclid=Cj0KCQiAoab_BRCxARIsANMx4S69fEEKqsHe-TrqYN1TYomIJXgiVHAZoXrtWGmVJO3suaPcEW57lTkaAht0EALw_wcB

Ninja'ed again :)
Also have a look at the Prairie-Masker System on warships.

https://en.wikipedia.org/wiki/Prairie-Masker

Bubble curtains attenuate sound by making water somewhat „compressible“. It doesn’t have to be a continuous wall of gas. I think it might be advantageous to have multiple rings.

The other objection i have is that they might build a platform with a flame diverter so that the exhaust gases are redirected parallel to the surface. And they can use huge amounts of sea water to take energy out of the exhaust gases.

Problem with a bubble curtain is that it makes the local water less able to support a floating ship due to change in density. There are suspicions that sudden gas boiloffs have led to unexplained sinkings, though that is at a larger scale than just one bubble curtain...
You‘re not putting the bubble curtain directly under the platform, but with some horizontal separation.

And bubbles are not necessarily a problem. It becomes a problem if the average density under the ship is so reduced that the ship isn’t buoyant any more. A bubble curtain can‘t do that. Huge gas releases of methane or so can do that. It‘s been one of the proposed explanations for the bermuda triangle (though AFAIK there‘s no statistical increase of ships disappearing in that region, and not even a clear definition of what the bermuda triangle is).

And this is why you don‘t want to drop in the bubble bath part of a wastewater treatment facility. In that bath you can‘t swim because the average density is so reduced, but you can drown there...
Did you know there is a torpedo designed to do this to a ship?
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Offline rsdavis9

Someone at another site concern-trolled the idea of “marine noise pollution.” Assuming the exhaust goes straight into the water, offshore SH launches would inject enormous amounts of acoustic energy into the ocean, on a regular schedule.

Not sure what to think about that.

Curtain wall bubbles was what I heard suggested.

A ring of seabed emplaced pipes/valves/nozzles that can inject large quantities of air into the seawater. They start doing this just before ignition, with sufficient time for the bubbles to rise to the surface from the seafloor. Tne nozzles are close enough together that there is little or no pure water between bubbles

This supposedly forms a curtain wall that will attenuate soundwaves a lot.

I can't remember where I heard this or whether it's ever been done at this scale. It would take a LOT of compressed air, that's for sure!

OK NVM:
This came up in another thread some time ago and bubble curtains look like something that may work.
https://canadianpond.ca/air-bubble-curtains-bubble-tubing/?gclid=Cj0KCQiAoab_BRCxARIsANMx4S69fEEKqsHe-TrqYN1TYomIJXgiVHAZoXrtWGmVJO3suaPcEW57lTkaAht0EALw_wcB

Ninja'ed again :)
Also have a look at the Prairie-Masker System on warships.

https://en.wikipedia.org/wiki/Prairie-Masker

Bubble curtains attenuate sound by making water somewhat „compressible“. It doesn’t have to be a continuous wall of gas. I think it might be advantageous to have multiple rings.

The other objection i have is that they might build a platform with a flame diverter so that the exhaust gases are redirected parallel to the surface. And they can use huge amounts of sea water to take energy out of the exhaust gases.

Problem with a bubble curtain is that it makes the local water less able to support a floating ship due to change in density. There are suspicions that sudden gas boiloffs have led to unexplained sinkings, though that is at a larger scale than just one bubble curtain...
You‘re not putting the bubble curtain directly under the platform, but with some horizontal separation.

And bubbles are not necessarily a problem. It becomes a problem if the average density under the ship is so reduced that the ship isn’t buoyant any more. A bubble curtain can‘t do that. Huge gas releases of methane or so can do that. It‘s been one of the proposed explanations for the bermuda triangle (though AFAIK there‘s no statistical increase of ships disappearing in that region, and not even a clear definition of what the bermuda triangle is).

And this is why you don‘t want to drop in the bubble bath part of a wastewater treatment facility. In that bath you can‘t swim because the average density is so reduced, but you can drown there...
Did you know there is a torpedo designed to do this to a ship?

And a catamaran.
Ghost in portsmouth nh

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #77 on: 01/07/2022 04:10 pm »
Someone at another site concern-trolled the idea of “marine noise pollution.” Assuming the exhaust goes straight into the water, offshore SH launches would inject enormous amounts of acoustic energy into the ocean, on a regular schedule.

Not sure what to think about that.

Curtain wall bubbles was what I heard suggested.

A ring of seabed emplaced pipes/valves/nozzles that can inject large quantities of air into the seawater. They start doing this just before ignition, with sufficient time for the bubbles to rise to the surface from the seafloor. Tne nozzles are close enough together that there is little or no pure water between bubbles

This supposedly forms a curtain wall that will attenuate soundwaves a lot.

I can't remember where I heard this or whether it's ever been done at this scale. It would take a LOT of compressed air, that's for sure!

OK NVM:
This came up in another thread some time ago and bubble curtains look like something that may work.
https://canadianpond.ca/air-bubble-curtains-bubble-tubing/?gclid=Cj0KCQiAoab_BRCxARIsANMx4S69fEEKqsHe-TrqYN1TYomIJXgiVHAZoXrtWGmVJO3suaPcEW57lTkaAht0EALw_wcB

Ninja'ed again :)
Also have a look at the Prairie-Masker System on warships.

https://en.wikipedia.org/wiki/Prairie-Masker

Bubble curtains attenuate sound by making water somewhat „compressible“. It doesn’t have to be a continuous wall of gas. I think it might be advantageous to have multiple rings.

The other objection i have is that they might build a platform with a flame diverter so that the exhaust gases are redirected parallel to the surface. And they can use huge amounts of sea water to take energy out of the exhaust gases.

Problem with a bubble curtain is that it makes the local water less able to support a floating ship due to change in density. There are suspicions that sudden gas boiloffs have led to unexplained sinkings, though that is at a larger scale than just one bubble curtain...
You‘re not putting the bubble curtain directly under the platform, but with some horizontal separation.

And bubbles are not necessarily a problem. It becomes a problem if the average density under the ship is so reduced that the ship isn’t buoyant any more. A bubble curtain can‘t do that. Huge gas releases of methane or so can do that. It‘s been one of the proposed explanations for the bermuda triangle (though AFAIK there‘s no statistical increase of ships disappearing in that region, and not even a clear definition of what the bermuda triangle is).

And this is why you don‘t want to drop in the bubble bath part of a wastewater treatment facility. In that bath you can‘t swim because the average density is so reduced, but you can drown there...
Did you know there is a torpedo designed to do this to a ship?
Which torpedo?
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

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Offline Asteroza

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #78 on: 01/08/2022 03:40 am »
Someone at another site concern-trolled the idea of “marine noise pollution.” Assuming the exhaust goes straight into the water, offshore SH launches would inject enormous amounts of acoustic energy into the ocean, on a regular schedule.

Not sure what to think about that.

Curtain wall bubbles was what I heard suggested.

A ring of seabed emplaced pipes/valves/nozzles that can inject large quantities of air into the seawater. They start doing this just before ignition, with sufficient time for the bubbles to rise to the surface from the seafloor. Tne nozzles are close enough together that there is little or no pure water between bubbles

This supposedly forms a curtain wall that will attenuate soundwaves a lot.

I can't remember where I heard this or whether it's ever been done at this scale. It would take a LOT of compressed air, that's for sure!

OK NVM:
This came up in another thread some time ago and bubble curtains look like something that may work.
https://canadianpond.ca/air-bubble-curtains-bubble-tubing/?gclid=Cj0KCQiAoab_BRCxARIsANMx4S69fEEKqsHe-TrqYN1TYomIJXgiVHAZoXrtWGmVJO3suaPcEW57lTkaAht0EALw_wcB

Ninja'ed again :)
Also have a look at the Prairie-Masker System on warships.

https://en.wikipedia.org/wiki/Prairie-Masker

Bubble curtains attenuate sound by making water somewhat „compressible“. It doesn’t have to be a continuous wall of gas. I think it might be advantageous to have multiple rings.

The other objection i have is that they might build a platform with a flame diverter so that the exhaust gases are redirected parallel to the surface. And they can use huge amounts of sea water to take energy out of the exhaust gases.

Problem with a bubble curtain is that it makes the local water less able to support a floating ship due to change in density. There are suspicions that sudden gas boiloffs have led to unexplained sinkings, though that is at a larger scale than just one bubble curtain...
You‘re not putting the bubble curtain directly under the platform, but with some horizontal separation.

And bubbles are not necessarily a problem. It becomes a problem if the average density under the ship is so reduced that the ship isn’t buoyant any more. A bubble curtain can‘t do that. Huge gas releases of methane or so can do that. It‘s been one of the proposed explanations for the bermuda triangle (though AFAIK there‘s no statistical increase of ships disappearing in that region, and not even a clear definition of what the bermuda triangle is).

And this is why you don‘t want to drop in the bubble bath part of a wastewater treatment facility. In that bath you can‘t swim because the average density is so reduced, but you can drown there...
Did you know there is a torpedo designed to do this to a ship?
Which torpedo?

I'm gonna assume they were thinking of a Shkval

https://en.wikipedia.org/wiki/VA-111_Shkval

But that uses a supercavitating bubble for propulsion purposes, not destructive purposes. Most conventional torpedos use their explosive to make a single large gas cavity bubble under the keel which promptly collapses, stressing the keel of the ship too hard and breaking it's back. I can't recall a torpedo with a water foaming warhead though...

Offline RedLineTrain

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #79 on: 08/03/2022 04:44 pm »
Just did some trawling through LinkedIn and SpaceX's job board and it's clear that at the end of last year, SpaceX started an offshore launch program referred to as either "Starship Offshore" or "Starship Offshore Engineering" and based in Cape Canaveral.

It looks like a modestly-sized engineering program for now.  Maybe a handful of engineers.  The team includes those who designed and built A Shortfall of Gravitas and at least one with long drill rig experience at Valaris.

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