At a normal pace, as BCV mentioned, it's about 10 minutes. You can get there in about 5 though with walking a little more briskly. I'm guessing that your probably concerned about only having 2 hours. So that you're not completely stressed out about time, I would suggest making your appointments for 9:50am. This will give you time to see your DS off, walk (not rush) to the spa, get checked in, escorted to the lounges and still have time to disrobe. I would also let them know that your DS is on the pirates cruise and that you do have time constraints. It's not unusual for the therapist to show up a few minutes late and again that could have you stressing out. A 50 minute massage, with about 20 minutes to relax afterwards (you absolutely need it ~ take it from someone who has quite literally walked into a wall afterwards) should put you back to the marina at about 11:10-11:15.
Option B, is that you can still make use of the healthclub/spa without having a spa appointment. I think it's a $14 per day fee and you can have a light workout or go straight to the lounge. They have one for men and one for women. Each has their own area for relaxing, changing, showers (with hair care products, razors, mouthwash, etc) and a whirlpool, sauna and steam room. Not quite the same as a nice massage, but you could go at your own pace and it may end up being more relaxing. Just another suggestion for you.
Tammi