You would tip the normal amount to the waiter in the dinning room even though you may not eat there every night. In the windjammer is a buffet style dinning, just like breakfast and lunch and you don't need to tip. Although we never had dinner in there, we always went to the dinning room, the meals were always very good there, although did have breakfast and lunch in the windjammer and that was also very good. One of my favorite aspects of cruising is having dinner in the dinning room with other tablemates and having the same waiter, etc.
Hope you love Explorer as much as we did, its a great cruise, have fun!
Tuesday Chat Host