This is a humorous statement. The idea is that the man speaking is accusing his wife of being immature (and therefore exhibiting behaviour and attitudes of someone younger than she is, possibly even like that of a child). He provides 'proof' supporting his accusation (the fact that she sinks his boats), but this proof indicates that he is perhaps the one who is immature. Taking a bath with toy boats is something usually associated with children.

lol

This requires and understanding of women. Still working on that.