ShipShape

delft said:

The purpose of the deep draft is to have the hydrofoils deep enough to feel little of the waves, thus damping the pitching and rolling, giving more comfort to the crew and let that crew work better also under a bad storm.
The hulls are narrow and the result is a higher wetted surface and more friction drag, but a lower wave drag which is the major drag component at high speed.

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I see. You are talking about SWATH (Small Waterplane Area Twin Hull) type vessels. These are outwardly similar to catamarans, but to minimise wave drag, the water-plane area is designed to be as small as possible. SWATH also has under water hulls to house the propulsion machinery and for stability.

SWATH uses its small water plane to avoid the influence of the waves. But I don't think a vessel of the size of a destroyer will be suitable for this configuration. A matter of scale. I also think that damage to one side of a SWATH might easily lead to loss of the ship. I therefore propose to fit a tricat with hydrofoils.

delft said:

SWATH uses its small water plane to avoid the influence of the waves. But I don't think a vessel of the size of a destroyer will be suitable for this configuration. A matter of scale. I also think that damage to one side of a SWATH might easily lead to loss of the ship. I therefore propose to fit a tricat with hydrofoils.

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Sounds rather unconventional, but should be workable. And it sounds like your idea is to maximise deck space and stability by having the hydrofoils.

Exactly. I also know, that helicopters cost ten times as much as winged aircraft, so if a ship wants to use small unmanned aircraft they had best be winged aircraft. They can be catapulted without runway and caught in a net when they return, that has been demonstrated, but if you want to use UAV's to large for such methods you might use a runway along the side of the hull.You don't want to mix small UAV's with manned aircraft on aircraft carriers.

And now for something entirely different. We saw a short while ago a photograph of a Chinese ship with somewhat miserable looking under water paint. That brought back to me something I read in the local paper a month or so ago. A small merchant vessel owned in the Netherlands is provided with a device invented by someone from this neighborhood that produces ultrasound. When the ship lays in a port the device is hung over the side, being moved all around the vessel, and its ultrasound destroys the cells of plants and animal that try to grow on the hull.
Current under water paint is loaded with poison to achieve the same effect, but that compromises the strength of the paint and it poisons the ports and their environs.More than a century ago oysters were only fit to be eaten by poor people. When the population grew and the oysters were poisoned the became too scare for poor people so they became a delicacy for the better off. So let's get rid of that poison.
A machine with near neutral buoyancy and connected to a electric power outlet, on board the ship or on an auxiliary, will push itself against the hull of a ship using a water stream square to the hull surface, the inverse of a hovercraft but in water, roll over the hull using water streams along the hull and produce the ultrasound in the mean time.
This means cheaper and stronger paint and more oysters and other sea animals for people to eat.