Having done something like what you are considering a few times here are my thoughts.
I had 5 [15/16y.o.] teens on board a schooner for 12 weeks on an E.coast Tall ship tour -- Miami-Halifax and another time in the Great Lakes. Most of the time with 2 adults and a college age team leader for the youth.
It is a 24/7 job! Maintaining any discipline is momentary. Reliance on any one job to be done right is best done one on one with clear instruction and faith. The down below will be a mess and few pieces of boat equipment will be where they belong. They will eat you out of provisions no matter what you start with. Acting in a group they will be fomenting adventures you will not believe. There is a lot of bickering and showing off egos.
You will concerned at all times for their safety - you will yearn for adult conversation - you will not be able to relax with a cocktail - you will be amazed at their reliance on you for all the stuff their Mom does for them - things will fall overboard when left on deck carelessly - cleanliness and ship shape will be a foreign language - frustration will be the order of the day for them and you.

I enjoyed my command and was very proud of my young crew often - in 12 weeks their maturity grew exponentially - instilling pride in new skills and teamwork was satisfying- but my crew wasn't ON Vacation and fun and total freedom for them was rationed as available.
It will take some special circumstances for you to end up being considered as a 'cool dad' and only then if you are somehow able to keep your attitude under control for a whole week amidst raging chaos at times.
Assuring their personal safety will be your main concern - they are young -- and feel bulletproof and prone to be constantly proving it to themselves and their peers.
All that said I hope you take them sailing!!! But your patience will be strained beyond any expectations and there may be young men you will lose any respect for and consider carefully the position you are putting your son in.