Humans have been sailing various seas and oceans for thousands of years, and using boats for potentially even longer than that. But as a species we wouldn’t have made it very far if it was only possible to sail in the same direction the wind is blowing. There are a number of methods for sailing upwind, but generally only up to a certain angle. [rctestflight] wondered if there was some way of sailing straight upwind instead and built this rotary sail craft to test the idea.
Normally a boat sailing upwind will sail approximately 45° into it, then “tack” 90° across the wind until they’re at another 45° angle from the wind, this time facing the opposite direction. This back-and-forth nature is not the most efficient path, so this vessel uses a few propellers to bypass the traditional sail. The first iteration, built on a sleek catamaran hull, uses a large propeller to catch the wind’s energy, then transfers it mechanically through a set of shafts to an underwater prop.
It took a few tries to get the size and pitch of both propellers narrowed down to where the boat would move forward into the wind, but move it does. A second major iteration of the build uses a single shaft with no gears, with the trade-off that neither propeller is facing an ideal direction, but this has the added benefit of the boat naturally pointing itself upwind.
While none of the designs are speed demons, the concept is sound enough. It’s just that, in most cases, performing multiple tacks to get upwind is acceptable compared to the extreme efficiency losses and drag from propeller-driven sailing crafts like these. A more effective way of propelling a boat upwind, at least using modern technology, might be to trade sails for solar panels.
This has been done on full sized sailing boats since the early 1970s.
Also there is an international student competition every year for over a decade driving races with this principle. On street and wheels, but physics are the same …
https://www.racingaeolus.org/History.html
>> On street and wheels, but physics are the same …
Sort of. the street doesn’t slip away sideways when you press against it, and you won’t usually drift with the wind unless your tires are *really* slick.
I told him…hehehe… we already got one
Yes, My friend Jim Bates did exactly that.
https://youtu.be/_YZO5i6DysM?si=ke-SLiS78VbismCh
I was also featured on the boat in WaterWorld.
The rudder works by bending the water flowing past it. If you put the rudder right behind the propeller instead of 50 cm behind it, the rudder would work on the speedy water from the propeller.
Also, a longer rudder (as in, horizontally) works better at low speeds.
So, it’s not sailing, really, it’s using the wind to power a propeller instead of an engine.
Eh. Using solely wind power to drive the craft (by whatever means) works w ought for me to call it sailing.
I mean. Some America’s Cup type foiling cats don’t even have a “sail” as much as a rigid moveable wing. Still counts imo
All sails are wings.
The that makes sailing SAILING is using the air to directly provide impulse.
If the sail itself isn’t pushing the boat, it isn’t sailing.
Not a new concept I think? Fairly sure I’ve seen a full size (30ft yacht) using wind vane. But while being hit on the head by the boom in a conventional boat is bad enough – the hazard from spinning rotor blades seems considerably worse!
Previously patented?
https://www.change-climate.com/Transport_Land_Sea_Sustainable/Assisted_Ships_Sails_Solar_Projects_Marine_Pollution/Rotary_Sails_Powered_Sailing_Boats_Ships_Turbines_Wind_Cars.htm
Even earlier patent from 1992, originally applied in 1989.
https://patentimages.storage.googleapis.com/c8/b1/a2/0799c75948ab7a/FI86831B.pdf
Apparently the turbine could swivel around 360 degrees and the boat would go in every direction regardless of wind direction.
https://sndp.mediadelivery.fi/img/1920/200597500.jpg
What’s missing is the pure joy of sailing!
Easily replicated by burning $100 bills while taking ice cold shower.
We have been keepiing a mini-cruising sailboat at a club, and sailing lots, for several years now, at a total cost of about 2 takeout coffees a day. No ascot required.
2 takeout coffees?
So $30-$50?
>might be to trade sails for solar panels
Or trade sails for an internal combustion engine.
That’s crazy talk. They’d need huge amounts of fuel, where is going to come from? The distribution network isn’t ready for it. It’ll never have the range needed for long trips. And what about the fire risk? So dangerous.
It will never catch on.
(caution: may contain traces of sarcasm)
Reminded me of a similar kind of question, sailing faster than the wind. The guy basically set up three rotating sails (a propeller) which were angled so they were permanently “tacked into” the wind, then set up a cart and off it went!
https://www.youtube.com/watch?v=jyQwgBAaBag