The racing rules are quite simply stated but in many incidents several rules, sometimes conflicting, may apply at the same time, as readers of the 48 North rules quizzes will know. However, it is possible to race successfully only knowing two key things: “If in doubt, give way” and “Don’t hit another boat”.
The full racing rules of sailing can be found here: Racing Rules of Sailing 2017 – 2020
And for those complicated interpretations of the rules, there is a Case Book with a whole bunch of examples: ISAF Case Book. Note that this will be updated later in 2017 to correspond to the updated rules.
If you don’t want to read the whole rule book, here are the the top 10 commandments of racing.
1) Port keeps clear of starboard. R10
2) Windward keeps clear of leeward when overlapped. R11
3) When on the same tack a boat astern keeps clear of a boat ahead. R12
4) A boat Tacking keeps clear of one that is not tacking. R13
5) If you gain right of way (R15) or change your course (R16.1), give the other boat time (Room) to keep clear.
6) The inside overlapped boat at three boat lengths from the mark is entitled to Mark-Room. R18
7) A boat that is backing-up (R22.3), taking a penalty turn (R22.2) or not racing must keep clear of other boats.
8) If you have broken a rule, always get well clear as soon as you can, and then take your penalty turns. R44.2
9) It is better to give way than to hit somebody.
10) Avoid collisions. The Racing Rules are defensive and intended to prevent collisions. R14
This list comes from SAILX a pretty nice sailboat racing simulator game.