Basic Navigation: Understanding Right of Way
The rules for who has right of way on the water have one basic purpose: to keep you and everyone else on the water safe. To do that they spell out for you who has the right of way in any given situation (the vessel which is less nimble), while at the same time making it clear that no matter what all vessels must take all reasonable measures to avoid a collision - even if it means you giving way to a vessel that ought to give way to you. The easiest way to sum this part of the navigation rules up may be this: if you can move around more easily on the water it's your job to stay out of the way of those who are less maneuverable.
The rules rank vessels by order of priority, giving the highest priority to vessels which have the most difficulty maneuvering. The ranks, starting with the highest, are as follows:
1. Not under command - a vessel which, for whatever reason, cannot control where it goes.
2. Restricted in ability to maneuver - a vessel which, because of the tasks it is doing, cannot change direction or speed easily, or at all.
3. Constrained by draft - a vessel which must stay away from shallower water to avoid running aground.
4. Vessel which is fishing or trawling (but not trolling).
5. Sailboat under sail or a boat being paddled or rowed - though as soon as the sailboat uses an engine for power it must follow the same rules as a power boat, whether or not it has sails up.
This means that a power boat must stay clear of a sailboat; power boats and sailboats of boats must stay clear of boats which are fishing or trawling; power boats, sailboats and fishing boats must stay clear of vessels which are constrained by draft; power boats, sailboats, fishing boats and vessels constrained by draft must stay clear of vessels which are restricted in their ability to maneuver; and all of them must stay clear of any vessel which is not under command.
Once you are clear about the types of boats which have priority, you need to understand how to pass, cross or overtake another boat on the water. Everyone is expected to know and obey the rules, since knowing what you should do and what others will do helps to prevent accidents. Assuming (and it seems a safe assumption if you are reading this) that you will be out on the water in power boat or sailboat, here is what you need to know.
First you need to understand what it means to be either the stand-on vessel or the give-way vessel. The give-way vessels seems obvious: that is the vessel that must give way to the other. The stand-on vessel then is clearly the vessel that has the right of way. But it is important to understand that even though the give-way vessel must take steps to cross, pass or overtake the stand-on vessel safely, the stand-on vessel is obligated to do what it can to maintain its course and speed until the give-way vessel has safely passed. The rules define which vessel you are according to the situation you are in, and then make it clear what action you should take.
Take the situation where you are at the helm of a power boat and see another power boat approaching. In this case there is no give-way or stand-on boat, but the rules tell you that if you and another boat are approaching each other head-to-head, then each should move to starboard (right) far enough to pass safely. If, on the other hand, you see another boat approaching from your starboard side you are the give-way boat, and should change direction so that you can pass safely behind it. If the other boat is approaching from your port (left) side, you are the stand-on boat and should hold your course and speed (as long as it safe to do so) until the other boat has passed behind you. If you are overtaking the other boat, you are the give-way boat and must pass at a safe speed and distance; if you are being overtaken you are the stand-on boat and must try to hold your course and speed.
A powerboat which needs to avoid a boat under sail or one which is being rowed or paddled should turn to go behind them. It's best to keep in mind that a boat under sail is being driven by the wind, and that changes in wind direction or strength have a direct impact on their progress. Since the wind does not always blow steadily, you should keep a close watch when passing and allow lots of room. On the other hand, if a sailboat is overtaking a power boat, the sailboat is the give way boat and must take care to pass safely; the powerboat is the stand-on boat and should maintain its course and speed until safely overtaken. And a sailboat with its engine going must obey the same rules as a powerboat, whether or not it has sails up.
Sailboats have their own set of rules to obey when meeting another sailboat, and these are based on the relationship of each boat to the wind. If one sailboat is approaching another, the boat which has the wind coming over the starboard side (and the main sail on the port side) is on starboard tack and is the stand-on boat; the boat which has the wind coming over the port side (sails on the starboard side) is on port tack and is the give-way boat and must pass safely. If you are on port tack and not sure which tack an approaching boat is on, it's best to take action to avoid the other boat and do it early enough to make your intention clear to its crew. If two sailboats are traveling in the same direction, then you need to know which boat is to windward and which to leeward. The windward side of the boat is that over which the wind blows; the leeward side is the side generally away from the wind. If there is a sailboat on your leeward side, you are the windward boat and it is the leeward boat. The windward boat must keep clear of the boat on the leeward side.
There are also rules to be aware of when traveling in channels, rules that help make sure the traffic flows safely and smoothly. Each vessel must keep to the starboard side of the channel, the rules of priority apply and smaller boats must stay out of the way of larger vessels. If you need to cross a channel, do so at right angles when it is clear so that you can cross safely and as quickly as possible. Anchoring in a channel is not allowed, since you will get in the way of others using it. If you are in a narrow channel and find yourself approaching a bend you cannot see around, give your horn one long blast. Anyone hearing and approaching should do the same to let you know that they are there. And to be safe, keep a sharp lookout at all times for other traffic and hazards.
There is much more to learn, but this is a start. Take time to make sure you know and understand these rules; it is your responsibility to learn whatever you need to to keep yourself, your passengers and others safe on the water. Besides, boating is much more relaxing and fun when you understand what you are doing!