Because the previous rule 18 applied at marks and obstructions, it created a two-length zone around every obstruction (such as other boats on the starting line or starboard tackers upwind). If boats were not overlapped before they were two lengths from these obstructions, inside boats were technically not entitled to room from outside boats. In reality however, most sailors did not consider the overlap situation at each zone as they reached down the starting line with everything happening very quickly. The new rules remove “zones” from all obstructions by breaking the old rule 18 into two new rules (rule 18 for rounding marks and rule 19 for passing obstructions). Under new rule 19, if boats are overlapped when they get to an obstruction, outside boats must give inside boats room to pass the obstruction, even if they weren’t overlapped before arriving at the obstruction. The only test for an inside boat establishing an overlap between an outside boat and an obstruction (other than a continuing obstruction) is whether the outside boat is able to give the inside boat room from the time the overlap is first established (see rule 19.2(b)). This does not represent a big game change.
But there will however be a small change on the starting line in the situation where a boat astern is considering sailing in between two boats that are luffing side by side. Right-of-way boats in a race can still be “obstructions” but in the new rules they are never “continuing” obstructions (see definition Obstruction). This will change the “test” for whether a boat astern can establish an overlap between two other boats. Under the previous rules, on the starting line a boat astern (B) could establish an overlap between a leeward boat (L) – which was the obstruction - and a windward boat (W) only if there was room for her to pass all the way between them in safety (windward boats used to let their booms hang out to leeward to narrow this space). The “test” under the new rules however is whether W can give B room to keep clear of L from the time the overlap begins (see rule 19.2(b)). It will still be tough for B to put her bow into a tight space because B has to initially give W room to keep clear when she becomes overlapped to leeward of W (rule 15), and give her room to keep clear if she then luffs (rule 16). But, if W can respond and create the space B needs, B is entitled to be there. The same will be true on a downwind leg when B approaches two boats ahead (L and W).
