The submersible depict on this Antigua & Barbuda stamp of 2000 depict a PERRY CUBMARINE of which the site submarines on stamps give http://www.submarinesonstamps.co.il/History.aspx?h=347
But I believe this information is not complete true, the submersible depict is the PC-3A type of which two have been built.
An American diving enthusiast and a Florida news-paper publisher, John H. Perry Jr. believed that there was a need for a recreational submersible to protect the divers from shark attacks.
In 1962 Perry manufactured his first successful “recreational” submersible, (he built before already two submersibles which were failures) She could dive to 150 feet and was at one point called SUB ROSA later designated PC3-X.
But he found out that there was much more need for an industrial and scientific submersible where after he started to build the 600 feet deep dive two men submersible PC-SB in 1963.
PC-3A (1 or 2) was built by Perry Submarine Builders, Riviera Beach, Fla. In 1964/1966.
Weight 4,790 lbs, dim. 18.5 x 3.5 x 5.75ft (height), draught surface 3.5ft.
Main propulsion is a stern mounted 7 hp, 36V, Allis Chalmers motor.
Total power 7.5 kwh, cruising speed 2 knots for 8 hour, maximum speed 4.5 knots for 5 hours.
Operating depth 300 ft.
Crew 1 pilot and 1 observer.
Payload 750 lbs.
Owned by Kentron Ltd, Hawai and he operates these submersibles for the US Air Force and US Army.
Both were used for missile location on the Kwajalein Island missile range.
Both were decommissioned in 1975. Fate unknown.
Antigua & Barbuda 2000 $1 sg?, scott?
Source: Manned submersibles by Frank Busby, which you can read on line.