Understanding navigational rules or Colregs (Collision Regulations) and knowing which is the stand-on boat or which is the give-way boat, is essential to learning how to sail. Colregs are largely based on the principle that the more maneuverable boat should keep out of the way of the less maneuverable boat.

Colregs can be broken down into three parts:

• rules of navigation between sailboats;
• rules of navigation between sailboats and powerboats (includes sailboats under power);
• rules of navigation between power boats.

The term 'right-of-way' does not apply to watercraft. Instead, a boat is either the stand-on boat or the give-way boat. The stand-on boat is required to maintain it's course and speed. The give-way boat must stay clear of the stand-on boat. If a give-way boat is approaching a stand-on boat, the give-way boat must notify the stand-on boat of it's intentions by making a clear and decisive change in course or speed.

In determining whether you are the stand-on or give-way boat go through the following process:

• Are you on a sailboat or a power boat (includes a sailboat under power)?
• Is the other boat a sailboat or a power boat (includes a sailboat under power)?
• If you are both on sailboats, what tack are you on and what tack is the other boat on?
• If you are both on sailboats and both on the same tack, which boat is closest to the wind?

Are you operating a Sailboat (undersail) or a Power boat? Is the other boat a Sailboat (under sail) or a Power boat? Power boats, as a general rule, must give way to sailboats.

If you are a power boat and the other boat is a sailboat undersail, you must give way. Alternatively, if you are a Sailboat undersail and the other boat is a power boat, then you are the stand-on boat.

There are however, a few exceptions:

• vessels not in command (i.e. not under control);
• where it is too difficult for a large power boat to navigate in a small channel;
• where the powered vessel, due to its size, has difficulty in navigating at the best of time;
• vessels engaged in fishing.

As a general principle, stay well clear of large powered vessels; they have difficulty in maneuvering, they may not see you and you could capsize in the wash.

What tack is the other sailboat on and what tack are you on?

If you and the other boat are sailboats (under sail), this is the first factor you must determine.

The Colreg rule is that the sailboat on a Port Tack must give-way to the sailboat on the Starboard Tack.

If you and the other sailboat are on different tacks then it soon becomes obvious who Stands-on and who Gives-way (port gives-way to starboard). The rule of upwind gives-way to downwind has been overridden by the rule of port gives-way to starboard - which boat is upwind and which boat is downwind becomes irrelevant.

If you are on the same tack as the other sailboat, which boat is windward?

The Colreg rule is that the sailboat closest to the wind (upwind sailboat) must give-way to the leeward (downwind) sailboat.

As a cautionary note, the windward sailboat's downwind vision is likely impaired by it's sails. Even though you may be the downwind sailboat (stand-on), never assume that the windward boat can see you.

Remember, this Colreg rule only applies if boats are on the same tack. If boats are on opposite tacks then the 'port gives-way to starboard' Colreg overrides this rule.

In some situations it is difficult to tell which tack the windward boat is on either because of distance, reflection off the water or just general all around poor visibility. In such situations the Colregs specify that if you are on a port tack and unable to determine the tack of an upwind boat, then you are to assume that you are the give-way boat.

Why port tack? If the downwind boat were on a starboard tack then the upwind boat would have to give way to the downwind boat no matter what tack they were on. If however, the downwind boat is on a port tack, then in theory, the upwind boat would only have to give way if it was also on a port tack. If the upwind boat is on a starboard tack then the downwind boat on a port tack must give way. Which tack the upwind boat is on is therefore only relevant if the downwind boat is on a port tack.

It is better to have two boats trying to avoid each other rather than guessing which is the stand-on or give-way as they eventually collide.

When wanting to pass a slower boat headed in the same direction you have the option of passing the boat on either your port or starboard side.

Colregs require the exercise caution when passing. It is important that no oncoming boats, water depth or width of channel will impede your ability to pass. You must pass at a safe distance from the boat being passed.

The boat being passed is always the stand-on vessel whether it is a sailboat or power boat. The boat being passed must not alter it's course or speed.

Always indicate your intention to pass and the side you intend to pass on. This is where the proper use of sound signals becomes important.

If an overtaking vessel wishes to pass a vessel on the starboard side then it should sound 1 prolonged blast (4 to 6 seconds). If the vessel being overtaken is in agreement, it need not respond. If the overtaking vessel disagrees with the intended action, it must sound 5 short (1 second) blasts -the danger signal.

Alternatively, if an overtaking vessel wishes to pass a vessel on the port side, then it should sound 2 prolonged blasts. If the vessel being overtaken is in agreement, it need not respond. If the overtaking vessel disagrees with the intended action, it must sound 5 short blasts - the danger signal.

In nautical terms this means that the port side of your boat passes the port side of the other boat or port-to-port.

In this situation there is no stand-on boat, each boat must give-way and alter it's course or rate of speed to safely pass.

When two power boats are not meeting head on but their paths cross (like cars meeting at an intersection), the boat on the starboard (right) is the stand-on boat and the boat on the port (left) is the give-way boat.

This, although sounding straightforward, can be confusing when power boats meet at a slight angle (are they meeting head on, are they crossing or is it an overtaking situation?).

A boat is head on when it coming at a direction straight off the bow. To determine if a boat is crossing or overtaking, consider the angle of light from the steaming (masthead) light. Masthead lights shine from straight ahead to a point 22.5 degrees abaft (behind) the beam on either side. If another vessel is within that range, then it is considered a crossing vessel. If the other vessel is more than 22.5 degrees abaft the beam then the other vessel is consider an overtaking vessel.

Safety first so never assume that the other boat views the situation the same as you do. If you are unsure of the other vessels intentions, try and raise them on the VHF or sound the danger signal - 5 short blasts.