The Sirocco did not sink on a reef as depicted in the film. In fact, the yacht is still in use today.
Charlie, who claims to be the true owner of the yacht, calls it the "Sirocco." Flynn gave her the name Sirocco. The previous owner would have called it the "Karenita".
A reef is a submerged outcropping of coral or rock. When the Sirocco sinks it is shown as going down in deep, open water, when in fact it should have been shown rolling off the reef.
Dook and Rex are throwing up from sea-sickness, yet it can be clearly seen from the water that the boat is docked and is not rocking.