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The Physics of Sailing (2003) (unsw.edu.au)
50 points by Tomte 8 days ago | hide | past | favorite | 23 comments





Tangential, but does anyone know of a video game that really gets sailing right? The best I knew of was Valheim, but it is not really great at all, I don’t think tacking works… at all?


There is a very fun, and somewhat realistic global sailing navigation program. Look up sailnavsim. It is a sailing simulator not visual. (Except for maps.) You can join races, start a random race, and/or create your own races. By yourself, or against others.For example during COVID, we organized a open race from England to South Africa. The race runs in real time, so for open ocean races, depending on where you are going, it can take weeks. You leave your boat at a certain heading, then can leaner three computer - for an hour, a week, or whatever. But the wind can change. Using a wind map( link provided) you adjust your headings. Then check your SOG( speed over ground). If you're not careful, you might actuality go backwards. Also avoid Islands in the middle of the ocean( zoom in on the map.) So, in terms of navigation is quite realistic.

Sailaway and eSail on Steam are OK if it’s winter and the lakes are frozen but as a sailor I just couldn’t get into it, plenty accurate but I’d rather just go sailing.

Sailaway III is a very realistic sailing simulator, with real airflow and sail and rigging controls, and real-time weather.

https://youtu.be/nljz2UW40hA

https://sailaway.world/


Ultima IV, Quest of the Avatar. Okay maybe not entirely, but it's more accurate than your average game's concept of 'sailing in the same direction as the wind = fast'.

Ehh you definitely have to tack if you want to go somewhere windward. You can do about 45 degrees into the wind. In valheim.

check out sailwind

The article mentions Sydney harbours 18 foot racing skiffs. These are very light 3 man racing vessels with far more sail than boat. They are very fast and require all 3 crew to be suspended on trapeze wires far from the hull, just to stay upright.

They are fun to watch because they flip and capsize a lot.

https://www.youtube.com/watch?v=8UqXaTHG0_M

https://www.youtube.com/watch?v=hmKQY0KdKSo


Want to go full physics nerd? Sailing can be described in terms of reference frames. While to an outside observer a sailboat can travel about 45 upwind, from the boat's reference frame one must add the forward speed to the wind vector, putting the "apparant wind" much closer to directly ahead. A modern sailcraft like a windsurfer really does feel as if its travelling directly into the wind, or is making its own wind. Going almost as fast as a car, hovering above the waves, directly into the wind, feels like magic because it basically is.

https://youtu.be/1VoGXcj4nvc

(Note how the real magic starts when they switch to the windsurfer's reference frame.)


A high-performance foiling catamaran can, under the right conditions, make progress against a 10-knot current by using the apparent wind generated by the current itself. As the current moves past the stationary water, it creates a relative wind of 10 knots that the catamaran’s sails can harness. By angling its sails and using its foils to minimize drag, the boat can generate thrust and lift, potentially achieving a speed over water faster than the current. This allows it to tack or gybe efficiently, making indirect progress upstream.

Learn about CE (centre of effort) and CLR (centre of lateral resistance) and then you can sail a boat without your rudder.

Was a challenging but fun thing to learn, and then teach to other kids.


Rudder movement is excess drag, the best of the best steer with the sails and weight placement.

Best to use physics to aid and minimize the drag of a rudder, Rather than eliminate it completely, but yes.

Nearly fell out with a guy over rudderless sailing in my intro to sailing course years ago.

It's not a "intro to sailing" skill, it's fairly advanced.

But yes, it is something that requires great teamwork and can certainly lead to conflict.


Side note: this classic webpage loads crazy fast without all the bloated JavaScript present in modern webpages.

Too bad that I can barely read it on my phone because the text is so tiny.

That’s not due to lack of JavaScript but rather missing the HTML heade’s meta name=viewport’s device width and scale.

I can't take this page seriously. It entirely fails to mention https://en.wikipedia.org/wiki/Coand%C4%83_effect

Real sailors arrive using the "colada" effect but lately there's been a growing reliance on the "chelada" effect since Modelo introduced those tasty red cans! They go down fast and make a day of sailing go even faster.

Coandă isn't a meaningful factor in the aerodynamics of sailboats.

It is perhaps possible that it contributes somewhat to the slot effect, but that is controversial.


Nor C.A. Marchaj: "Sailing Theory and Practice".



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