Rules, what rules?
Although some of your fellow boaters haven’t heard, “rules of the road” to prevent collisions between watercraft are the LAW.  On the oceans, these rules are called the “Colregs” or Rules for Prevention of Collision at Sea. Inland, we have the “Inland Rules”, which are similar except for a few details such as when you should blow your horn. Sailors will also hear quite a bit about Racing Rules, but these only apply among racers. Otherwise, the regular Colregs/Inland rules take precedence.
One basic idea of the rules is the more maneuverable boats “give way” to less maneuverable boats, which should “stand on” a steady course so the “give way” boats can avoid them. This basic idea means that sailboats often, but not always, have the right-of-way over power boats.
Exceptions:  Sailboats “give way” to “vessels not under command” and large vessels in traffic separation lanes or channels, restricted maneuverability vessels such as dredges and ferries, or tugs and barges, and commercial fishing vessels engaged in trawling, long-lining, purse seining, etc. (Note: Using your Zebco to cast a plastic worm off your Bassmaster Turbo does NOT make you a “stand on” fishing vessel under the rules!)  Also, sailboats using motors, even with sails up also, are considered motor boats.
If you and another boat, both under power, are converging, the boat on the right has the right of way. At night, you may see the rightward boat’s red port-side light – that means watch out and get out of the way.
Otherwise, sailboats under-sail-only have the right of way over motorboats, EXCEPT when overtaking/passing.
Among sailboats, those with the wind coming from their right (“starboard tack”) have right of way over those with the wind coming from the left (“port tack”).
If both are on the same tack, the boat that’s further upwind (“windward”)
must give way and yield to the boat that’s further downwind (“leeward”).
This rule came from the days of the old square-rigged windjammers, which were far more maneuverable downwind than if attempting to go upwind.
Overtaking boats must yield/give way to boats ahead of them. An obvious exception would be a big ship coming down a channel behind you.
IN ALL CASES, you should take necessary steps to avoid an imminent collision (“general prudential rule”) even if you have the right of way. If don’t have right of way, then you MUST take early, obvious action to “give way” and use whistle/horn signals whenever required or needed.
Also, if you value your hull and hide, respect the unwritten Law of Gross Tonnage.
These are just the critical highlights. You should study the rules, via a book, pamphlet, video, or safe boating class. Special rules apply in many situations. Rules are written for making passing, danger, and fog sound signals, for example. You should also know about requirements for lighting, know how to read a nautical chart, and know how buoys and other aids to navigation work before sailing in busy waters.
Racing sailors use many special rules & terms, such as start rules, mark rounding rules,  “anti barging rules,” “luffing rights,” “buoy room,” proper course,” etc., but racers must also know the regular rules, which apply when they meet non-racing boats as well as in all non-regatta situations. As a courtesy and to show good seamanship, non-racers are urged to give room to racers whenever feasible; racers likewise should show awareness of the general rules and of the limitations of other boats.
Pat Byrnes