Pieces of Eight! Pieces of Eight!
“It was a long, difficult business, for the coins were of all countries and sizes—doubloons, and louis d’ors, and guineas, and pieces of eight, and I know not what besides, all shaken together at random. The guineas, too, were about the scarcest, and it was with these only that my mother knew how to make her count.” — Treasure Island, Ch. 4 “The Sea-Chest”, by Robert Louis Stevenson
Pirates don’t generally store up GURPS dollars in their treasure chests. The 3rd Edition GURPS Swashbucklers gives conversion factors for many currencies that were popular in the 17th century, but those are 3rd edition dollars, not 4th edition. So, I decided to do some math.
According to GURPS Basic Set: Characters, page 264, a pound of silver is worth one thousand GURPS dollars. According to Wikipedia, pieces of eight were supposed to contain 25.561 g of silver. Incidentally, they were also 38mm in diameter, just about the same size as an Eisenhower dollar. The pieces of eight had a lot more silver in ’em, though.
That comes out to right around $56.35 each. That is one darned inconvenient number.
Luckily, we’ve got plenty of wriggle room. I can round of history to the nearest round number and still claim authenticity. So.
Let’s say that minting silver into coins adds enough value that a piece of eight is worth $60. (That’s GURPS dollars, remember, not U.S. currency.) That means “two bits” is worth $15.
Taking that value back to the conversion tables in GURPS Swashbucklers, it turns out that a gold doubloon is worth $300, a gold French louis d’or is $180, and an English guinea is $315. An English shilling comes out to $15, making a penny worth $1.25.