28 feet minimum
It can be performed on a Catamaran or a monohull. For a Catamaran endorsement, it must be performed on a 36 ft length minimum Catamaran.
The SLC license will list the qualified length of vessel to be 10 ft (3m) larger than the boat that the student has listed at least 5 days of being master in their eLogbook. This is independent of the vessel size that the assessment was performed on
For example, if the student has entered a 31ft boat in their logbook as the largest boat that they have sailed as master of the vessel for 5 days, and the assessment was done on a 28 ft boat, then the SLC license will qualify the student for upto 41 ft.
Keep in mind that the assessment does require 50 days of sailing experience and at least 25 as master of the vessel and at least 25 on a vessel greater than 28 ft.
All of these requirements are used in order to ensure the competency of the license holder.