Starting line rules: OCS, recalls, and the start sequence

More tactics and more rules come together at the start than at any other point in a race. Knowing the signal sequence and the cost of being over early matters to every racer.

The standard start sequence

Most races use a five-minute sequence of visual and sound signals from the race committee (RC) boat:

The preparatory flag tells you which starting rule is in force. Flag P is the standard signal with no extra penalty. Flags I, Z, U, and the black flag bring progressively stricter penalties for being over early, described below. Some events use a different sequence, so always check the sailing instructions.

OCS: on the course side at the start

A boat is On Course Side (OCS) when any part of its hull is on the course side of the starting line, the side towards the first mark, at its starting signal. To start correctly a boat must be entirely on the pre-start side when the signal is made.

Being slightly over early is one of the most common mistakes in racing, especially in a crowded fleet where boats are trying to hit the line at full speed.

Individual recall

When the RC identifies one or more boats as OCS, it signals an individual recall:

• It makes one sound and displays code flag X promptly after the start.
• As a courtesy it may also call or post the sail numbers of the OCS boats, but Rule 29.1 does not require this. The flag and sound are the recall; identifying individual boats is not the race committee's obligation, so it is on each sailor to know whether they were over.

A recalled boat must return completely to the pre-start side and start correctly before racing on. Under the I flag rule it must instead sail right around one end of the line (see below). While returning, it must keep clear, under Rule 21.1, of any boat that is not returning.

If an OCS boat does not return and start correctly, it is scored OCS. Under the low-point system that is one more than the number of boats entered in the series (N+1), the same as a DNF.

General recall

The RC signals a general recall when either:

• so many boats are OCS that it cannot identify them all, or
• the start was otherwise unsatisfactory.

The signal is two sounds and the First Substitute flag. The whole fleet returns, and a new start sequence follows.

Penalty starting flags

I flag (Rule 30.1). During the last minute before the start, any boat that is on the course side of the line must sail back to the pre-start side around one of the ends of the line. Simply dipping back across the line is not enough.

Z flag (Rule 30.2). A boat with any part of its hull in the triangle formed by the ends of the line and the first mark during the last minute receives a 20% scoring penalty (ZFP), without a hearing. The penalty stands even if the race is restarted, unlike the U flag.

U flag (Rule 30.3). A boat in that same triangle during the last minute is disqualified without a hearing (scored UFD). The penalty does not apply if the race is restarted or resailed, so a general recall clears it.

Black flag (Rule 30.4). The strictest penalty. A boat in the triangle during the last minute is disqualified without a hearing (scored BFD), and that disqualification stands even if the race is given a general recall. The black flag is used when the RC needs to force the fleet to hold back from the line.

Managing risk in the final minute

The challenge of starting is to be as close to the line as possible at the gun without crossing it early. Experienced racers keep track of:

• their position relative to the line, using transits or a bearing on the pin end,
• how much time is left,
• which flag is flying, so they know the penalty for being over.

Being a few lengths back at the gun is costly in a fleet start, and being OCS is worse. The judgement is how close to push it. Under a black flag, that judgement shifts firmly towards caution.

Last updated: 2026-06-15