We are working on a seastead design.

Above the water there will be a big triangle frame.  The
left and right sides will be 70 feet long and the back part of the triangle will be 35 feet wide.
The point opposite the 35 ft side is the front.
The triangle frame will be a truss structure that is 7 feet high (floor to ceiling).
It will be enclosed and the whole inside the living area.  Lots of glass to see out.

There are 3 legs/floats/foils/wings that provide the buoyancy, so it is a bit like a trimaran but with a very soft ride.
Each leg/wing will 19 feet long and have a NACA 0030 foil shape with 10 foot chord and 3 foot width.
Each of the 3 legs will be attached to the underside of the big triangle near one of the 3 points (but the total top of the
leg will be inside the triangle) and going down so that the lower half is in the water.
This makes for a "small waterline area" similar like a small oil platform but one that can move through the water easier because of the foil shape.
The 3 legs will all be parallel with the blunt or "leading edge of the wing" side facing forward so it is low drag for the seastead to move forward.
Each leg will be 50% under the water (so 0.5 * 19 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.

There will be 6 RIM drive thrusters of 1.5 foot diameter, one on each side of the 3 legs/wings about 3 feet up from the bottom.
These RIM drives will have the flat sides toward the front and back of the seastead.

On top of the roof there will be solar all over.

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 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.
Also behind the back on the left and right of the dinghy will be a deck that is 5 feet wide extending beyond the back of the triangle.

There are 3 stabilizers that look like a little airplanes, one attached near the back of each main seastead leg.  
The little airplane has a 12 foot wing-span, 1.5 foot chord, the body 6 feet long, and the elevator has a 2 foot wing-span and 6 inch chord. 
A small actuator makes the elevator angle up or down so it can adjust the angle of 
attack of the main wing of this stabilizer without needing a large actuator.
This is really the "servo tab" idea.
While the thick part of the leg is 3 feet wide the back where the airplane will attach is very thin.  And to get the airplane's
center of lift to balance on the pivot a notch into the front/center of the wing only has to go about 25% of the chord of the wing.

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.

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.   




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.