We have been staying at Coral Bay for nearly four years, usually 3-4 times a year. Noise from the barge has been minimal. Activity is restricted to the daylight hours and for the most part the restrictions are adhered to. Work has begun on the new marina and commercial depot on the backside of the island off the lagoon. This will proceed very quickly, or over a matter of months, depending on the attitude of the Belizians.
There are about a dozen of the best properties on the island that are in proximity to the current barge, and the daylight activity has had little or no effect on their attractiveness or occupancy. Interestingly enough, the daylight activity can provide some VERY interesting and humorous moments when one is inclined for such "entertainment". According to many members of this board the prime viewing position is one of the bar stools at the beach bar in front of Coconuts (I have a bit of "personal" experience with this).
In short, we have had traveling companaions spread all up and down the beachfront in that area during our trips. The most common "complaint" is from the noise made in the early a.m. by the tropical birds. Boy, can they get your attention!