The stamp has the inscription French Ketch, we nowadays known the type as a yacht rigged vessel, but already the name ketch was used from before 1634.
From the 17th to the 18th century it was a common name and was mostly used as a trader, but also as a warship (bomb-vessel).
She was distinguished by the lack of the usual foremast. The mizzenmast was stepped forward of the rudder post. She sets a square sail plus a fore-and-aft sail
The tall mainmast stepped just abaft amidships, sets square sails plus a fore-and-aft lower sail, original a lateen, later a gaff sail, and a square topsail.
Long bowsprit with 2-3 jibs.
Strongly built.
Approx. 16 x 5.5 x 2.7m.
Crewed as warship with 30 – 50 men and armed with 10 guns.
The stamp shows most probably a bomb vessel I can see 4 gunports on the starboard side.
Grenada 1989 $4 sg2020, Scott1732.
Source: The Mayflower and other colonial vessels by William A Baker. Aak to Zumbra, a dictionary of the World’s Watercraft.