Cars, race cars, trucks and construction equipment are more popular than boats.
My grandson only became interested in boats after we started taking him out on the water with us. Last Christmas I found a truck with a boat and trailer similar to our Formula. When he shows off the boat he calls it "PopPop's boat". He also has a little car that he rides on and tries to attach things to the back of it so he can tow them around pretending it's our boat trailer. It's cute.