If you're a sailboat racer, or what to become one, you need to become familiar with the Racing Rules of Sailing. Here are some references to help you learn.
Links and Resources:
by Ken Quant, 2009
"Jimmy shut us out!"
Protest: Failed to keep clear, failed to take two turn penalty. https://www.cnn.com/2017/12/28/sport/sydney-hobart-comanche-race-intl/index.html