As an Argentine my interest is focused on the search for the disappeared submarine ARA San Juan.

My knowledge of submarines is limited to guppies. It was only recently through Wikipedia that I found out that the Guppy Class  of American submarines (WWII vintage) was a cute acronym that was perhaps so by accident:

The Greater Underwater Propulsion Power Program (GUPPY) was initiated by the United States Navy after World War II to improve the submerged speed, manoeuvrability, and endurance of its submarines. (The "Y" in the acronym was added for pronounceability.)

The navy began the program by testing and reverse engineering two captured German Type XXI U-boats: U-2513 and U-3008. That analysis led to four goals—increasing the submarines' battery capacity, streamlining the boats' structures, adding snorkels, and improving fire control systems. The navy immediately focused on designing a new class of submarines, but the Bureau of Ships believed the fleet of existing Gato, Balao, and Tench class submarines could be modified to incorporate the desired improvements. In June 1946, the Chief of Naval Operations approved the GUPPY project. The initial two-boat test program, implemented by the Portsmouth Naval Shipyard, eventually grew into several successive conversion programs. Those upgrades proceeded in seven variants, in the following order: GUPPY I, GUPPY II, GUPPY IA, Fleet Snorkel, GUPPY IIA, GUPPY IB, and GUPPY III. Some boats that went through an early phase were then upgraded further in a later phase.

A similar programme for the Royal Navy involved modifications to 24 wartime and post-war British T- and A-class submarines, which were provided with streamlined hulls, sail-type conning towers, and increased underwater performance during 1948-60.

While being a conscript seconded,1966-67,(from the Argentine Navy, Armada República Argentina or ARA for short) to the Senior US Naval Advisory group I had the job of translating documents of all kinds. I wrote personal letters for my boss Captain USN Onofrio Salvia but I also had the tough job of helping to write operating and maintenance manuals for “surplus” US Navy equipment that the Argentine Navy purchased from the US. Some of this equipment was sent for free. I would go often to Electrónica Naval near the Parque Lezama with documents on radar equipment that was either being given or sold dirt cheap. At Electrónica Naval the crafty Argentines built TVs and had carpenter sailors make very nice cabinets. These were sold to the public with fake Zenith or other brand names attached to them.

But there were two serious purchases that had me boarding a Guppy Class submarine and climbing into the cockpit of a Douglas Skyhawk (the latter were shot down in droves by the British in the Malvinas War).

I would inspect these war machines with American non-commissioned officers who would explain what this or that was. One of my helpers was a US Marine flyer colonel who had the shakes because of the experience of having fought in the Korean War (called a Police Action in reality).

Sail of the French nuclear submarine Casabianca; note the diving planes, camouflaged masts, periscope, electronic warfare masts, door and windows.

It was the Guppy that presented me with a double problem that was never solved so I had to convert the conning tower to torre “conning” and sail became just that ‘sail’.

The difference between a sail and a conning tower is almost subtle as both look the same from the outside. What happened is that a lot of the sensitive equipment that was held in the vertical and protruding superstructure when a submarine is surfaced was transferred below ships from the conning tower which instantly became a sail.