Pig and Rooster on the feet.

Pigs and Roosters aboard ships were stored in wooden crates. When ships would sink, the wooden crates would float, and more often than not, the animals inside would survive. This brought about the superstition amongst sailors that the 2 animals couldn't drown. So, they would get a pig on their left foot, and a rooster on their right foot, with the superstition that if the ship went down, they could guide the sailor to shore.

Nautical stars were also extremely common. Nautical star, or the North Star, was a invaluable navigation tool for sailors, so many ended up getting a tattoo of it, with the superstition that it would help guide them home.

Fouled anchors have evolved over time, and held dual meanings by some, but it generally represented either someone who had sailed across the Atlantic, or someone who had become a Boatswains (a high ranking non-officer)

From there, there was different tattoos that may have come from that time period or before, such as fully rigged sailing ships indicating one who's sailed around Cape Horn, turtles for those who have crossed the Equator, rope on the knuckles for deckhands (sailors who work on the decks), swallows for 5000 miles traveled at sea, dragons for having been to Asia, etc etc etc. These are more unknown as to the general time they came about, but are likely from around that general time period.

Sailors today even commonly get these tattoos, but more so out of respect of the traditions of the high seas rather than superstition. I can't count how many friends of mine from the Navy who have at least 1 of these tattoos, as well as my father and grandfather who had their pig and rooster tattoos.

I have to point out though that these are more American and British sailor tattoos, since vast amounts of US naval tradition came from their experience with the British navy, not sure how well those traditions carried over across other countries.

I'd be interested to learn the origin of the 'fouled anchor'. . ? Surely a fouled anchor would be unusable or dangerous, so this seems a strange thing to choose as a motif.

While I can't speak specifically for British and French sailor's, I can speak on American sailors during this time period. Tattoos where extremely dangerous to get back than due to high risk of infection and probability of death so when getting tattoos it had to mean something. During this time period British sailors would commonly try to escape the Royal navy and join merchant ships in the United States. This caused British ships to stop American merchant ships and impress run away British into service. Many of the British subjects who ran from the British would get tattoos of patriotic eagles to try and hide from the Royal Navy. American sailors would also get these tattoos out of fear of being impressed.

• Simon P. Newman, “Reading the Bodies of Early American Seafarers,” William and Mary Quarterly 55:1 (January 1998): 59-82.

While researching old tattoos I've gone through thousands of records from Civil war era. For dates earlier than this I haven't seen anything compiled with info on sailors except a smattering of examples in prison records.
You can enjoy some the records here. The majority of them seem to be religious, initials (of I assume a loved one), anchors and the like, and sometimes women as a representing an ideal -like lady liberty.
If you page through the Naval records I linked to you'll see some peopel recording the scars and permanent marks go into detail, some do not.

edit: here's a blog post about the Irish sailor tattoos from this same era/set of records

tag along question (but I can start another post if required). I am aware that seamen and (I believe) soldiers have their "go-to" tattoos.
What about other jobs? Would farmers or smiths or any other groups from that same era and area have "typical" tattoos? thanks!

Many sailors would get tattoos of religious figures or other sacred imagery on their backs to discourage lashings, hoping that whoever was giving them the whip would not want to deface the image by scarring them. Amusingly, in the Soviet navy, sailors would get tattoos of Stalin, Lenin, or Marx for the same purpose.