To work on Small Commercial Vessels which are under 24m and carrying less than 12 passengers, the type of qualification you need will depend on the area you are operating in. The main qualification is an RYA Practical Certificate which then needs to be Commercially Endorsed.
Category 6
To sea, within 3 miles nominated departure point in favourable weather and daylight.
RYA Powerboat Level 2 (12 months experience required)
Pre-requisites: None, RYA Essential Navigation may be useful
Duration: 2 days (plus online learning if needed)
Category 5
To sea, within 20 miles nominated departure point in favourable weather and daylight.
RYA Day Skipper Motor practical course
RYA Day Skipper theory course (online or in the classroom)
Pre-requisites: 2 days seatime on a motorboat
Duration: Theory either online learning or 5x days in the classroom, practical 4x days on the motorboat
Category 3 & 4
20 miles from a safe haven
RYA Yachtmaster Motor Coastal prep course (can also be used as Mate qualification for Category 1, 150 miles).
Pre-requisites: Theory to Yachtmaster Coastal/Offshore level, valid / in-date First Aid and VHF/SRC licence.
30 days seatime, 2 days as skipper, 800 miles, 12 night hours. Reduced to 20 days, 2 as skipper, 400 miles, 12 night hours if you have the Coastal Skipper course completion certificate.
Duration: 5 days
Category 3 & 4
20 miles from a safe haven
RYA Advanced Powerboat course
Pre-requisites: Theory to Yachtmaster Coastal/Offshore level, valid / in-date First Aid, and VHF/SRC radio licence.
2 years relevant experience including night pilotage, as a guide 30 days seatime, 2 days as skipper, 800 miles, 12 night hours. Reduced to 20 days, 2 as skipper, 400 miles, 12 night hours if you have the Advanced Powerboat course completion certificate.
Duration: 2 days + 1 day for exam
Category 1 & 2
150 or 60 miles respectively
RYA Yachtmaster Offshore Motor prep course
Pre-requisites: Theory to Yachtmaster Coastal/Offshore level, valid / in-date First Aid and VHF/SRC radio licence.
50 days seatime, 5 days as skipper, 2500 miles, 5 passages over 60M including 2 overnight and 2 as skipper.
Duration: 5 days
To Commercially Endorse any of the Skipper certificates you will require these additional qualifications:
MCA STCW Personal Survival Techniques 1 day
MCA Elementary First Aid 1 day
RYA VHF/SRC Radio Operator online or 1 day
RYA Professional Practices and Responsibilities online
ENG1 or ML5 Medical