How would a seastead fair in a storm?


(adam ulbrich) #1

what happens in a storm with a seastead?


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(Bob LLewellyn) #2

There are many designs for a seastead. The answer to your question is dependent on the design however the optimum solution would be to duck under the water like a submarine and resurface when the storm is over.

An alternative to that design would be to stay surfaced but batten everything down tight and let the waves crash over the seastead and roll back into the sea on the other side. The third way is to make your seastead so big, it would be impervious to any wind and wave.

Small boats are mobile and can sail out of the path of the weather but some designs for a seastead would have some protected facilities for smaller boats to ride out the storm in.

Probably the most practical would be Mati’s triangular design. The structure would be very big allowing a sizable protected marina inside the walls.


(Larry G) #3

Broad questions with no parameters are not very useful. What is a storm? What does a seastead look like? What sea state parameters is your seastead designed for?

https://wiki.seasteading.org/index.php?title=Sea_state

https://wiki.seasteading.org/index.php?title=Waves

https://wiki.seasteading.org/index.php?title=Low_Cost_Wave_Tank

How about build a model and see?


#4

Which us why I ultimately chose the Ramform hull. The North Sea is more inhospitable than the Gulf of Mexico, with storms on the same scale as hurricanes. Given it’s also the location of the Draupner Event, rogue wave, something previously undocumented, a vessel designed for, and based of known performers in those conditions would be highly beneficial.

Not saying I’d WANT to be in a hurricane, but the ability to handle severe conditions, in a proven design, is certainly a desirable set of traits.


(stephen russell) #5

Seasteads can have like " Storm shelter" modules for High Seas etc thus occupants enter Module to decend to say 100 ft depth until storm passes OR
Place Colony Under retractable Dome?? See Logans Run domed city idea, 1976 movie.
Or whole Colony can submerge while say hurricane rages above.
& rig Colony for “rouge waves” too.
Only options I see aside beefing up Surface complex alone to take wave hits etc.
& tap Wind for energy storage.


#6

Problem with any sort of retractable dome will be sealing and pressurizing for submergence, followed by decompression times and so on.

100ft may seem reasonable, but any extended duration at that depth will cause a need for decompression stops, to prevent the ‘bends’

I’ve chosen both a suitable, proven hull design, and to make hatches face aft, rather than up, or forward, in an effort to reduce the chance of taking on water from the most likely directions.


(stephen russell) #7

Said dome would be pressurized thus NO decompression req save for any divers outside at time But those within would NOT undergo decompression.
Or dive to 50 ft depths Below storm surge waves then.
& do examine"rogue waves", very scary 100ft + waves appear out of no where.
Must for ALL Seastead projects, Rogue Wave Defense.


#8

OR, since this is science fiction now, just launch the seastead in orbit so it can weather the storm there.


#9

Maybe you should get your PADI certification, before you make such broad statements about diving… If you’re in a pressurized vessel, breathing air, that air is pressurized. There are timetables, but they are very approximate, and times vary for every individual and every circumstance.

I’ve been a certified PADI diver for over 25 years.


(Bob LLewellyn) #10

JL, I think Stephen just left out the negative, I think he meant non-pressurized or pressurized to one atmosphere. However, the point that he was making, would seem to be valid, you would want your construction to be able to withstand the pressure at 100’ but you would only need to drop the structure below the trough of the wave to miss the toughest part of the storm.


(Larry G) #11

You are incorrect. Pressurizing to match outside pressure WILL require decompression time. even at quite moderate depths. The amount of nitrogen build-up in your system depends on the combination of depth AND “bottom time” that you’e exposed to. And if you come directly back up without deco, you will blow nitrogen bubbles through your alveoli and into other painful places, like joints, bones, sinuses, blood vessels in your brain, etc. If you spend a full day even at 30 only feet, safety factors will require slow decompression.


(stephen russell) #12

Thank.ypu Forex.that’s exacty.what I meant and.Temporary.undersea time.during storm


#13

If it’s temporary enough not to require pressurization and decompression, then it’s not worth the effort to submerge.

By the time you close, dive, wait, rise back up, you’re talking hours, even days, not some 15 minutes drop to the bottom of a pond.

At least look at the PADI time tables and study the process, so you have some concept of what you’re trying to consider. We’re not talking about putting storm shutters on, inflating a few seals and weathering a storm here. You specifically said a removable dome and submerging to wait out the storm. I’m being realistic, here, not trying to be difficult.


(Larry G) #14

Regardless, designing a structure that can withstand outside pressure with only one atmosphere inside, or equalizing pressure, you’re still talking about a highly complex system to maintain a seal over such a large area, and to open it up widely when not submerged. It’s not very practical even if theoretically possible.


#15

Free Access Observed Oceanic Response over the Upper Continental Slope and Outer Shelf during Hurricane Ivan*

Abstract
Hurricane Ivan passed directly over an array of 14 acoustic Doppler current profilers deployed along the outer continental shelf and upper slope in the northeastern Gulf of Mexico. Currents in excess of 200 cm s−1 were generated during this hurricane. Shelf currents followed Ekman dynamics with overlapping surface and bottom layers during Ivan’s approach and transitioned to a dominant surface boundary layer as the wind stress peaked. Slope currents at the onset of Ivan were wind driven near the surface, but deeper in the water column they were dominated during and after the passage of Ivan by subinertial waves with a period of 2–5 days that had several characteristics of topographic Rossby waves. Currents on the slope at 50 m and greater depths commonly exceeded 50 cm s−1. Surprisingly, the strongest currents were present to the left of the storm track on the shelf while more energetic currents were to the right of the hurricane path on the slope during the forced stage. Near-inertial motion lasting for a time period of about 10 days was excited by the storm on the shelf and slope. Record wave heights were measured near the eyewall of Hurricane Ivan and were shown not to be rogue waves. The large surface waves and strong near-bottom currents caused significant bottom scour on the outer shelf at water depths as deep as 90 m.

http://journals.ametsoc.org/doi/abs/10.1175/JPO3115.1


(Larry G) #16

This is the kind of information that is necessary in the forum and makes good wiki articles. Many people, myself included in the past have blithely assumed things that would get people killed if we were successful enough at raising money to build something carelessly.


(.) #17

1 centimeter per second = 0.036 kilometer per hour
1 cm/sec = 0.036 km/h

1 centimeter per second = 0.0194384449 knot
1 cm/sec = 0.0194384449 kn

200 cm s-1 = 3.88768898 kn
100 cm s-1 = 1.9438449 kn
50 cm s-1 = 0.971922245 kn

kn = knot ; cm s-1 = centimeter per second


#18

Point is, folks have been assuming they would be unaffected if they just sink below the waves. Scouring means the removal of surface material, Scouring at 90m means dropping 100ft would be a bad move, at best


(Bob LLewellyn) #19

There are currents down there, ones that have toppled sunken ships. But submarines go through that all the time. And they move causing a greater movement of water compared to itself as one just floating under the surface. When we start building something that will duck under the water, it will be to standards that can take the abuse.

Remember that we had a professor at Clemson that had agreed to work with us once we got to phase two. His specialty was fluid dynamics, our project would have been right up his alley. I don’t think he would have made that kind of mistake.

Going low or under the waves is just to keep it from bouncing in turbulent waves. Now I know that works because I have been on both a loaded and empty barge and empty ones dance in the wind…

The other observation from above is about dome covers. I would not think that a structure would need a dome cover if all the windows had water tight portal covers. Doors and hatches too. The structure would be divided by large interior walls making individual water tight cells. Any water breaking over that kind of a structure would just run back into to sea.


(.) #20

Well, I am trying to understand this paper.
One of my difficulty is the mixing of the units: miles, kilometer,
meter per second, centimeter per second.
Wind speed is given in meters per second, current speed is in centimeter per second.
If I understand it correctly, this is in 100 m deep water on continental shelf in
the Gulf of Mexico near Alabama shores.