The fastest way to get a Boat Operating license in Hong Kong to join a course. If you use google and check for Boat Operating License you will find the companies that provide such a course. They will Book an examination date for you from the Marine Department of Hong Kong. The Exams are held almost every week.
You will need 2 licenses. Grade 2 Masters to operate the boat, and Grade 2 Engineers to understand engines. Having these 2 licenses enables you to operate pleasure vessels or yachts upto 15m (Roughly 50 ft). If you want to operate bigger yachts. Then you will need Grade 1 license. For which you will have to wait for a year or more until you reapply.
There is no practical exam to get boating license. Unlike car license. This is only multiple choice questions. Approximately 40 questions. In the course you will learn basics and go through some syllabus in the book. But mainly you will have to go back to the center to do past papers and practice passing the exam. This is easiest way and some centers guarantee 100% passing rate, as-in if you fail the first trial, they will let you come to the center to do the past papers until you pass.
Time period of this course depends on the students. Roughly people do the course and practice for 2 to 3 months. If you find it easy you can do the exam earlier.
Cost of this course for both licenses is under HKD 10,000/- . More of less depending on different centers, their locations and no.of. students they teach at a time.
It is advised that after you get your license, you approach your instructor and ask them to give you some practical lessons if you are going to buy a boat for yourself in HK.
You might find this article interesting about Buying boat for the first time.