These 3 postcards date from 1942 and use the popular Popeye cartoon character to lend a light-hearted look to life in the US navy. I imagine a sailor could mail one home to let his parents know he was OK and humorously tell them how important he was to the Navy and war effort.
In the first one, the anonymous sailor (you could fill in your own name in the cartoon bubble) beats up Popeye who was known for his strength and his love of spinach.
The second postcard shows how popular the sailor is with women [WAVES was a division in the Navy and stood for Women Accepted for Volunteer Emergency Service.]
The bottom image shows the captain (Popeye's friend Wimpy who was known to always be eating a hamburger) telling Popeye to place the So-and-So in the front row for the inspction.
There are several others in this series, these 3 being the only ones I own right now.