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. I want to analyze the active stabilizers designed for this seastead. What is the additional buoyancy force of an additional foot of water around one of these legs? If a stabilizer could reduce 6 inches from the crest of a wave and 6 inches off the trough then it could make a 4 foot wave feel about like a 3 foot wave, right? The current plan is for each leg to have a stabilizer, so we can look at what one stabilizer does to one leg. Please estimate how many inches this can remove from the crest or trough, and total inches, as well as electrical power lost to drag, at the following speeds: 4 knots 5 knots 6 knots 7 knots 8 knots If we make this out of marine aluminum about how much would you estimate it would cost for the airplane and the small actuator? If this was an optional extra for the seastead how popular do you think it would be with customers? When estimating costs assume a batch of 20 will be made in China. Sometime a series of waves can make something with a resonant frequency near the wave period move much more than one wave but an active stabilizer can really help get rid of this issue. Another interesting case is really large swells, say a 12 foot swell with 12 second period and the seastead is going directly into it (head sea). As we are climbing up the side of the wave, we could have the front stabilizer try to lower the front and the back two stabilizers try to lift some to keep the seastead more level even on this giant wave. What it the wavelength for a 12 second wave in the Caribbean? When the seastead is at the steepest part of this swell, given the length of the seastead, how much higher could the water at one end be than at the other? How much help could this mode of stabilizer operation do in this case to keep the seastead level? And in a beam sea could it do even better? When the airplane stabilizer is moving through the water it can control the angle it is at but when the seastead is at anchor and moving up and down there is may be a problem. The pivot at the "wing center of lift" for the stabilizer is 25% along the chord is in balance when moving. However, when the seastead is stationary and bobbing up and down in the waves the 75% of the wing on one side and 25% on the other will not balance. So the stabilizer will rotate one way when the leg is going down and the other when the leg is going up. So I think we need to have another actuator that can lock it in position when. Please describe a possible design for this locking mechanism and estimate the cost. When the stabilizer is off where the tail will stay straight, or it could be "locked off" where it can not move. When the stabilizer is off or locked off, it will act as a heave plate and still provide some motion damping. When the stabilizer is on the stabilizer wing can be angled which will cause more drag for the seastead. But if the stabilizers are on the 3 legs will not be bobbing up and down deep into the water as much, which could mean some reduction in drag. I am guessing that on net it will take more energy to move at a certain speed with the stabilizers on, but not as much as a simple "drag of stabilizer" calculation might imply. What do you think? Can you estimate how much extra power it would take to move with the stabilizers on at 4, 5, 6, 7, and 8 knots? Show both drag from stabilizer and any savings from the legs moving more level. We will have a separate power system in each leg, so the 3 stabilizers will have 3 independent power supplies. They will each have their own computer and can operate even without central control (they just feel their own motion and try to resist it) so there will be independent failure modes. If something goes wrong with one stabilizer the odds are we still have two others working and that should still do a good job of stopping resonant motion.