certification I can work with

[roland stockham]

AS you have lots of sea time already but, as you say, not done the nav stuff your start point could be to do they RYA shore based courses. This cover all the nave theory, rules of the road etc, is cheap and can be done as an online course. there is a 'day skipper' and 'coastal skipper' level. Once you have done that you can jump straight into the Yacht master program. Depending on experience it may be worth looking at the coastal skipper course which focuses on skippering skills like close quarters boat handling MOB etc. The yacht master is more about crew handling and running the boat and assumes your are an experienced skipper. Look through the syllabus or email one of the training schools who will be happy to advise you.