I feel I should explain the time limit in this case, before our RC is ripped to shreds!
We sail on an estuary, with a max sailing time of 4 hours, and more often 3 hours. This event is part of an annual series with a wide range of mixed fleets. Most only have a single race, but some (dinghies and cats) schedule two races per day / regatta, with the intent they should last about an hour. There is an elapsed time limit of 75 minutes, and then there is the gate of 20 minutes after the first boat finishes. Most of this is a given in the circumstances. As you can see, it has lead to a problem in this rare case where competitors exceeded the 20 minutes and the first boat(s) were later RAF'd for missing a mark. As it happens, the boat which is querying the rule also exceeded the 75 minutes, so the rest is a moot point now.
It does however raise the general question of how to manage the cut-off when the first boats RAF or are DSQ'd (what happened in Texel?).
We have also realised the need for these slower cats to be catered for with shorter courses for all, or perhaps they should race against the monohulls of similar speed. The shorter course option may be preferable, since the slow cats in questions are typically raced by the youths, whom we wish to encourage!