We are working on a seastead design.

The goal is to design our seastead such that all the parts can pack into a single a High Cube 45 foot container which has:
   width 7.7 ft
   height 8.9 ft
   length 44.6 ft
   max weight:  62,000 lbs  (rated bouyancy at desired waterline is 27,500 lbs and we hope structure is enough under this that humans and their stuff can fit)

Above the water there will be a big equilateral triangle frame, 44.0 feet on a side. 
The triangle frame is also the wall of the living area and will be 7 feet high (floor to ceiling).
It will be enclosed and the whole inside the living area.
Around the whole outside of the wall, except where the dinghy is in the back, will be a 3 foot wide walkway and railing that 
is bolted on and has some diagonal supports from below bracing to the wall (so walkway is 1 food higher than bottom of the wall).
The walkway will have an aluminum grating that would let a wave pass through but you can walk on.
Also two doors on the back side,  one two feet in from left and one two feet in from the right side. 

There are 3 legs/floats/foils/wings/keels that provide the buoyancy, so it is a bit like a trimaran but with a very soft ride.
Each leg/wing will 14.5 feet long and have a NACA 0040 foil shape with 8.5 foot chord except that the last 0.5 feet of
the thinnest part will be cut short, so with foil does not come to a point at the trailing edge and fits within 8.9 feet
hight of container.  But the buoyancy is very close to that of an 8.5 foot chord foil.
Each of the 3 legs will be attached to the underside of the big triangle near one of the 3 points.
The center of the thickest part and going 1.5 feet in all directions from there will be within the area of the triangle,
but within that constraint, each leg will be as close to the point of the triangle as possible.
The legs will go down so that the lower half is in the water.
This makes for a bit of "small waterline area" similar like a small oil platform but one that can move through the water easier because of the foil shape.
It is not an extreme SWATH design as a 1 foot change in water level is about 1/7th of the total buoyancy, so still significant change.
The 3 legs will all be parallel with the blunt or "leading edge of the wing" side facing forward so it is lower drag when moving forward
than a typical cylinder on a semi-submersible platform.  
Each leg will be 50% under the water (so 0.5 * 14.5 feet) and the top 50% out of the water.
On the top half of the front of each leg, so the top half that is out of the water, will be a built in ladder.

The reason for these sizes for the triangle and legs is so they can pack into a container nicely and shipped to 
a shipyard anywhere for assembly.
Imagine the 3 legs end-to-end with thin/trailing-edge of foil up and leading edge down on the right side of the container.
So the right 3.4 feet of the container (width of legs) is used by the 3 legs.
Then the 3 frame/wall sections will be upright (so 7 feet high) next to each other along the left side of the container.  
I am not sure the width of the walls but if they were 10 inches wide then 3 widths is 30 inches and some extra is 3 feet on the left side.
There should still be lots of room in the center of the container for all the other parts.

Connecting the mid points of the walls both at floor and ceiling level will be structural beams that
make another triangle 22 feet on a side.  Then all the remaining spans will be less than 22 feet.
The rest of the floor and ceiling will be small pieces that are bolted in.

On top of the roof there will be solar all over.  With batteries and electric thrusters as the main propulsion system.

There will be 6 RIM drive thrusters of 1.5 foot diameter, one on each side of the 3 legs/wings about 2 feet up from the bottom.
These RIM drives will be all be fixed orientation to provide forward thrust.  It will use differential thrust to turn.
For slow movements in tight areas like harbors it can reverse thrust on one side and forward on the other to turn in place.

There will be a conduit/pipe welded to the back of the trailing edge to take electrical wires down to the thrusters.
There will not be any "through hulls" in the legs.  The legs will also have multiple
airtight compartments each for safety.


Behind the back near the center will be two supports going out and 2 ropes going down to a dinghy.
The dinghy is a 14 foot RIB boat (deflated for shipping) with an electric Yamaha HARMO outboard.  It is sideways against the center of the backside of the living area.
When the seastead is moving forward the dingy is shielded from the wind by the living area.

On the lower part of each leg will be several bolt on heave plates.  These will help dampen the response to waves.

About 25% of the displacement will be for LiPo4 batteries which will be put low in the 3 legs.
Each leg will have its own charge controller and inverter so there is triple redundant power on the seastead.
Also, the thrusters for a leg will get power from that leg's inverter or batteries.  So
the 3 pairs of thrusters will have independent failure modes as far as power.

When the seastead is going to be staying in one place for awhile, we can put down 3 helical mooring screws and give the seastead tension legs 
so it becomes nearly stationary when parked.  Near each corner there will be a pair of helical mooring screws with a motor unit between them.
We only plan to do this in the Caribbean where tides are very small and in protected places where the saves are small,
so pulling down 3 feet will be sufficient to never go slack.


Two seasteads will be able to connect together with a walkway, one behind the other, so that while underway 
people can move between seasteads, enabling a real community.  The two computers for the two seastead will both work thrusters
to minimize the movement of the walkway, particularly when warned that someone will be on it.




In many family yachts if a person falls overboard there is nearly a 50% chance
it results in death.  It can take a long time to turn a sailboat and get back
to the spot where the person was and it can be hard to find them in the waves.
How many people die per year from man overboard events?

Our seastead is far more stable than a normal family yacht, so the chance of
falling over is greatly reduced.  And it can stop easily and very fast.

Also not be necessary to outside to adjust sails, so that also should reduce
the chances of man overboard.

But we would like to have something cheap that really makes man overboard much safer.

I am thinking we will have everyone have a phone in their pocket anytime
they are moving around outside (already true for most people) and an app that is constantly checking in with the main
computer on the seastead.  If anyone fails to check in for some period, 
the seastead will sound an alarm, do a fast stop, and even back
up to the location between their last checking and when they failed to checkin.
The base station will record the location every second, the phones don't each need
to do that.

The phone has motion sensors.   If a person falls off it can send a "zero G event" 
message even before it hits the water.  So the exact time and location of the fall can be recorded.
However, using the accelerometer so often will cause significant battery drain so
probably this option should be off by default.

The app could send a message ever 1 second but the base can understand that sometimes
messages are lost and try to contact the phone that has not checked in to get it to
resend the last message.  We don't want one packet loss to cause a panic, that would be
far too many false alarms and make the system unusable.  So the base might 
do something like sound an alarm after 3 seconds, and then stop and return to
last location after 6 seconds.  

The seastead will have ladders so if it is nearby someone can swim to it and climb up.
So even a solo user could be saved by this system.

I guess if a phone goes dead then it could set off an alarm.
I guess the app needs to insist that the user charge their phone.

Maybe we have a thing on the door that can tell if it is opened without a phone
being nearby and sounds an alarm, as people should not be going outside without a phone.
This is extra hardware and so would be optional.

I expect yachts will all have starlink (or equivalent) and have wifi available all
around the yacht in the near future.  I am less sure that low power bluetooth will
work from anywhere on the yacht.  If we use wifi very often that can be a power drain.
So the app will try bluetooth first but if it can not connect then it will try wifi.

A key advantage of wireless systems is that water is highly opaque to 2.4 GHz frequencies (Wi-Fi and Bluetooth). 
The moment a phone or beacon submerges, the signal is instantly blocked. You don't have to wait for 
the device to float out of range; the submersion triggers the break. 

Some phones want to put apps to sleep, I am guessing there is some way a user can do a
setting of "never put this app to sleep", is that true?

How bad would the battery life of the phone be affected by an app like this?   Would
most phones still be fine to make it through the day on one charge? 

Again, I like that we already have phones in our pockets and they already can talk
to the local wifi or bluetooth devices, so this is just an software that can even be open-source/free.
My guess is that Claude Code or Cursor could write such an phone app and the
server computer code to just sound an alarm in a very short time, do you agree?  

Would most existing family yachts have a computer that could run the server code and at
least sound an alarm?  So they could download the app on their phones and the server 
code and be safer without any cost?

Seems like a simple (with AI writing code these days)  open source project that could
save many lives.   Like we could do this now, even before the seastead is built, and
it would be a great thing.  Years ago I did some Java phone app stuff and I remember
it being very painful just to get to "hello world".   With AI how hard is it to
get started now?   What tools would the AI use to make the app?

Have people done things like this already?   Please discuss any examples
and the issues for this type of system that we need to be careful of when setting it up.