Personalized 4th Birthday Sailboat Youth T-Shirt. Sailboat with number 4 for your child's 4th Birthday comes on a party Youth T-Shirt - Pacific Blue gift. Let the good times roll in a durable T-Shirt that takes kids from school to play in an amazing array of colors. 5.0 oz., pre-shrunk 100% cotton. Seamless 1x1 rib collar.