Culebra and Culebrita are part of what are called the Spanish Virgin Islands. They sit in-between the main island of Puerto Rico and the U.S. Virgin Islands (St Thomas, etc). This is where Puerto Ricans go when they have the time and the means. The owners of this website can often be found in Culebrita! Put simply, it is the pretty part of the territory and a favorite for locals and tourists alike.
Which hours/time frame?
You need a full day if you want to go to Culebra or Culebrita. A half day is not an option.
Which boats are best for this destination?
Any of the boats 30 feet and bigger can get you to Culebra and 40 feet and bigger for Culebrita.