50

No limits*, but go with kites. You can read more on Wikipedia. Long story short, kite sails are already used on ships of various sizes, especially big ones. Sure, not as the only propulsion system, but not due the lack of power. Problem is in wind unpredictability, but that's not true in your world. Current kites supplement up to 20% of power to a ...


21

While I don't have the math to work this out, some examples from the real world suggest you could actually get pretty impressive performance if you change your thinking about the sails. The America's Cup had a problem when designers started going way outside the box. Giant catamarans with wingsails are not, strictly speaking, yachts, but they certainly ...


17

A sail ship could be designed as large as a modern supertanker if we wanted to do that. There are a number of ways that we could harvest wind energy in order to move the ship. The so-called "rotor ship" concept is one. We can use what are effectively wind turbine towers instead of sails that can utilize wind from any direction and basically any velocity and ...


6

The largest sailing vessel without an auxiliary motor ever created was the Thomas W. Lawson at 145/120 m, mast-stern/deck, a third the size of a super tanker. This ship was ironically designed to haul oil and coal. The main limitations of this ship were difficulty in handling her near ports, if such large vessels were common, ports would have to be ...


4

I'd say you could easily scale the large sailing ships of 1900 by a factor two (-> 220m long or so), giving a factor eight in tonnage (-> 40 000 tons). Modern materials and technology keep the crew size in the same region, 40-50 people. Going away from full-rigged to schooner rigs or multi-mast sloop is possible with modern fabric and keeps crewsize further ...


2

Since you have predictable wind power, you could potentially set up wind farms (not attached to ships) that produce electricity to power large electric motors. As long as you have some energy store for this electricity (big efficient batteries) you can perhaps make motor boats much like the ones we have today with electric motors instead of combustion ...


2

Yes, but it depends on your level of timekeeping technology. Magnetic North and True North are not the same, nor are they even close when you get near the poles. The magnetic field of the Earth varies over time, and will even undergo complete reversals (where the North magnetic pole moves to the South true pole and vice versa). The difference between ...


1

Would you count a Flettner roter using the Magnus effect as a “sail”? Veritasium has a video on the Magnus effect and its usage in boats and planes. These boats with spinning cylinders rather than (or as well as) traditional sails can get quite large. A Gizmodo article refers to them as mega-ships, and describes Flettner rotors being retrofitted ...


1

Engineering-wise, the question on the size limit has a lot in common with the limitation on the weight of an aircraft. You have to consider the strength of available materials, when subjected to forces that attempt to bend or buckle them. As the length increases, it rapidly becomes impossible to make a sufficiently rigid wing (aircraft) or mast (sail). I ...


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