taking baby boating?

This weekend my family and I are going to our lake house and I really want to go on our ski boat. My son is going to be 5 months on the 11th and he’s 20lbs. He has his own infant life jacket but for some reason i’m just really scared to bring him on the boat. has anyone brought their baby on a boat yet this summer? not like a slow pontoon boat, i mean like a ski boat? i looked it up and i read the US coastguard says wait until baby is 18lbs to be safe in a life jacket, which he has passed already, but i just wanted other opinions or to hear other experiences. 😊