There are 3 berth cabins which are quite big enough for 2 ad and a 13 year old.
If you go to RCI website you can look this up for yourself. There is very little availablity for Aug08. A cat H oceanview is £1752.18 for all 3 of you. An inside room for 3 adults (over 11 is an adult) is £1545.80 for the same cruise in Aug09.