Pieces of Eight

The year is 1700 and the golden age of piracy is in full swing! Just five years ago, on 7th September 1695, Captain Avery led several pirate vessels to ambush a treasure-laden trading ship. The attack succeeded, with around £600,000 worth of jewels and golden coins stolen. Despite a large bounty on his head, Avery has managed to evade the authorities and hasn't been seen or heard of since. No-one knows what happened to his ill-gotten gains but spending such a large fortune would surely not have gone unnoticed, so you wager that most of the treasure remains hidden... and ripe for the taking! As luck would have it, a member of Avery's crew was recently captured with several mysterious crates in their possession. A few gold coins to the local officials, and you've been permitted an hour alone to examine them. Could they contain clues to where Avery's vast fortune is hidden?