Approximately 15 seconds before the starting signal. Boats A, B, C, D, E, F and G are holding their positions on starboard tack a short distance below the starting line. Boats L and W are approaching the line of boats from astern. There is insufficient space for both L and W to pass through any of the gaps between adjacent boats ahead of them.

If L becomes overlapped to leeward of D while W is clear astern of D, is L required to give W room to pass to leeward of D?

No. When L becomes overlapped to leeward of D, she obtains right of way over D, and therefore D is no longer an obstruction to L and W. For that reason, rule 19.2(b) does not apply between L and W. Instead, rule 11 begins to apply between L and D, but L is initially required by rule 15 to give D room to keep clear. W continues to be required by rule 12 to keep clear of D and by rule 11 to keep clear of L.

After L becomes overlapped to leeward of D, L has right of way over both D and W. Therefore, at that time L becomes an obstruction to D and W and, if W becomes overlapped with D, rule 19.2(b) begins to apply between D and W. Rule 19.2(b) requires D to give W room to pass between herself and L unless D has been unable to so from the time that W's overlap with D began.

If there is not space for both L and W to pass through the gap between C and D, does that mean that L has to allow W into the gap and not pass through the gap herself?

No.

According to the definition Obstruction, a boat racing is never a continuing obstruction. Nevertheless, are there any situations, such as the one in the diagram, where a row of racing boats sailing close to one another becomes a continuing obstruction?

No.

World Sailing 2011