An experienced mariner wrote:
Sailors would get the face of Jesus tattooed on their back because ship captains did not want to whip the face of Jesus. Also a classic: "HOLD FAST" tattooed on the knuckles for a tight grip when climbing all the ropes and rigging.
I'm a professional mariner, BTW. And as I was taught, an anchor means you're done sailing and have finally dropped your anchor somewhere.
A barn swallow actually means 5000 miles. I should have about fifty barn swallows, but I only have a mermaid I got in the Philippines, some waves I got at Goldfield's in San Francisco, and some Rarotongan characters that were done with a reed, a stick, and some india ink on the island where westerners first found out about tattooing.
They'd also get two swallows tattooed onto their chest for good luck crossing seas and 10,000 nautical miles. Also they would get pigs tattooed onto their feet for good luck.
The pig and the chicken are another item. "Pig on your knee, safety at sea" is the rhyme, and the chicken will supposedly always find something that floats in case the ship goes down.Its actually a pig & a chicken tattooed on their feet. Pretty damn painful spot.
Also, swallow tattoos aren't limited to a sailor's chest. They can be anywhere. Many Brit sailors have them on their hands."