Personalized 3rd Birthday Sailboat Youth Long Sleeve T-Shirt. 3rd birthday sailboat Youth Long Sleeve T-Shirt - White with number 3 on its sail makes a fun nautical themed party day gift for a little boy. youth long sleeve t-shirt. Shoulder-to-shoulder taping. Youth: S(6/8), M(10/12), L(14/16), XL(18/20)