I had the following situation once before. I wonder what the umpires think about this:
During the pre-start my opponent lets his (only) Y-flag fall in the water. He can no longer protest. The rest of the pre-start I'm trying to prevent him from picking up the flag from the water. (Unfortunately he eventually succeeded).
Imagine this situation: My opponent has no Y flag and I violate the rules in the pre-start time and again and then win the race. How far can I go? Will there be a time when the umpires will decide enough is enough and go for rule 2 without any Y-flag being displayed?
To answer your question I had a look at rule C8.3:
C8.3 When the umpires decide that a boat hasIf the umpires decide that you deliberately break the rules and/or commit a breach of sportsmanship, because you know your opponent cannot protest, they will use this rule and start handing out penalties. Preventing someone to pick up a flag - using the rules - is fine in my book. That falls under the same heading as preventing someone to enter. As long as you stay within the rules, perfectly legal. But if you start breaking rules to prevent the other boat from picking up its Y-flag, you break rule 2 as well. (See also Case 78)
(a) gained an advantage by breaking a rule after allowing for a penalty,
(b) deliberately broken a rule, or
(c) committed a breach of sportsmanship,
she shall be penalized under rule C5.2, C5.3 or C5.4.