We found information about the following specific ships:

HMS Investigator

Description: Merchant ship used in Arctic exploration

USS Investigator

Description: 1945 Guardian-class radar picket ship

HMS Investigator

Description: 1795 survey vessel

Aliases: Fram, HMS Xenophon, and Xenophon

HMS Investigator

Description: 1811 survey ship

HMS Investigator

Description: 1861 survey vessel

We also found the following citations which are not yet associated with specific ships: