Seems quite clear that the marina rats impeded the large vessel and are at fault here by ignoring rule 9B of colregs.
They should have "just got out of the way" because, as stated very clearly in other threads by knowledgeable people, "the rule
of tonnage" leads foremost in a collision
avoidance situation. Clearly. Obviously.
Rule 9 - Narrow Channels
(b) A vessel of less than 20 meters in length or a sailing vessel shall not impede the passage
of a vessel which can safely navigate only within a narrow channel or fairway.