Yeah. Boatpoker is right about not having owners aboard - they frighten the life out of ya and it's difficult to maintain control of events
. They are not all the same though. To be fair, I've had some good ones - usually sailboats.
If you were working USA waters Road Runner, I would almost certainly go for USCG certification
. However, once you have the appropriate USCG Tickets, there is nothing to stop you gaining the RYA/MCA qualifications, simply by reading the RYA course specifications for any different material, then going strait in for the two and three day exams as appropriate. You don't have to do everything all over again for the RYA - experience counts for a lot.
Also note, that $450 a day, works out at just over $10 an hour for a crew of two - in deliveries you quite often work 24 hour days on the longer jobs. Boatpokers advices are good.