I cheated a little bit and don't calculate the fluid dynamics in real time. Instead, I'm using force models from the excellent Aero-Hydrodynamics of Sailing book by Marchaj, which is sadly out of print. I then do iterative balancing of the drag force and combined drag/lift forces on sails until they converge.
SailRhythm is a bit WIP, so didn't want to share too early!
Thank you so much for the detailed feedback. I do have plans to implement wind flow visualization and have a way to visualize forces as well. Controls a bit tricky to do, but this is definitely something I've been pondering. As you said, at certain headings the changes sometimes are too small to perceive.
If other people are interested in sailboat physics -- this resource is a goldmine of information on how sailboat and sails work and physics around it: https://www.onemetre.net/Design/Design.htm
Definitely recommend taking an introductory ASA 101/102/103 classes from a local school! Will help you decide if you are into it while having some fun.
I built one recently to mostly help myself visualize how sail trim worked and how various boat controls like mainsheet and backstay affected sail shapes, various forces and boat performance. It uses a physics-based VPP and I calibrated it against Catalina 36 polar charts, so should be pretty precise!
I plan to integrate the simulator with the sail trim guide I'm building to help people learn.
There is a great school called Modern Sailing School in Sausalito. I highly recommend taking a class from them. I took one in the past and they are great!
Will help you figure out if you are into sailing or not.
Not my demo! But I got inspired by it some time ago to build a simulator for monohulls which uses a physics based VPP to calculate the boat speed based on input controls like mainsheet, jib sheet, travelers, backstay and so on at https://www.sailrhythm.com/
It uses Catalina 36 Tall Rig as a base model for sailboat parameters and was calibrated to match ORC-published polars for it within 1-5% on both close, beam and broad reaches.
Mostly built it for myself to help me understand how less common control affect the sail shapes, angles of attack and boat heel and behavior in a visual way.
It's still WIP, but you might find it useful for yacht-specific stuff!
Even still a lot of information is not online. I've been building a web sail trim simulator and had to hunt down a physical copy of the Aero-Hydrodynamics of Sailing book by Marchaj, because a lot of the formulas and models I needed to simulate the boat were not online, and what was online was often wrong.
This site is an absolute treasure trove of technical material on sail and hull design, with a focus on model yachts but most of the physics scales up. It covers aerofoil theory (momentum, circulation, lifting line), sail twist, downwash, planform effects, Reynolds number, hull resistance, appendage design, VMG, and more.
Lots of spreadsheets and practical calculators too—bulb shape optimization, wetted surface area, simple VPP models. If you're into sail performance modeling or yacht design, this is one of the best resources out there.
Land in desirable areas is limited and zoning and other government red-tape prevents high-density housing from being built (or any housing being built period in cases like San Francisco).
I can't believe I'm arguing that it's immoral to steal on HN, but here we are...
Yes, you might decide that breaking your moral code to feed yourself or your family is an acceptable tradeoff, but it's a tradeoff nonetheless. It's a conscious choice. A lot of people in history made a decision to go hungry instead.
Children might see the world in Marxist generics where some ambiguous, but for some reason always "wealthy" people stole all the fruit trees and poisoned the water. Adults usually deal with specifics. Who are all these mysterious people are? Do you think the food just fell from the sky before the industrial age? What do you think happened to the people who stole before the industrial age, hungry or not?
From the recent stuff, remember the lab leak theory where any mentions of which were getting removed from Twitter, Facebook and Youtube, including the scientific papers that looked into it?