Originally Posted By: AKSAR

Apparently the distress call was indeed heard and a rescue was launched. From St. Lucia police detail rescue after boat sinking:
[quote]When authorities received the captain's distress call, they dispatched a boat immediately, but it took 30 minutes to reach their location, Leonce said.

So if the swimmers would have stayed at the site of the sinking they would have been rescued after half an hour. That is how I understand it.