Many of the San Diego boats going to the Gulf of Tonkin were retrofitted with 30 and 50 cal machine gun mounts in the mid 60s.  In 1964 USS Diodon, for example, had gun ports installed port and starboard in the midlevel deck of the northern sail, with rectangular doors that would open.

Probably Pickerel received one of those informal upgun mods as well.

I can point to many significant details that are simply incorrect when it comes to information about the TENCH class. CDR John Alden's The Fleet Submarine in the US Navy is one of the more authorative and correct sources for basic information. But it also has some errors.

In working with PAMPANITO (a BALAO boat), we have found that the most reliable source of information comes from two sources - 1) new construction and post-overhaul shipyard photography; and 2) the war patrol reports that detailed modifications, new equipment, major repairs, etc. between war patrols.

TENCH boats came in near the end of WWII (did you know, for example, that 2 different TENCH boats were to bear the name WAHOO but never got built?) -- and the class history is pretty well summarized by Alden -- some were actually completed, some were under construction and broken up on the ways, some were under construction (including PICKEREL and VOLADOR), had construction stopped shortly after WWII ended, then completed in 1948 or 1949 as GUPPY-Is or IIs.

In a bunch of cases, entire contracts and building orders were cancelled - which explains the gap starting with SS-491 thru SS-521 as well as gaps between SS-427 and SS-434 as well as SS-438 thru SS-474 

SS-522 AMBERJACK, SS-523 GRAMPUS, SS-524 PICKEREL, and SS-525 GRENADIER were all stopped sometime after WWII but got a reprieve when they were completed as GUPPY-IIs.

Then SS-526 thru SS-562 were cancelled outright as part of the end of WWII - which explains yet another gap in the hull numbers.

PAMPANITO is fortunate to have a solid archive - but even then, there are significant differences between what the class plans and booklet of general plans might show and the configuration as the boat really had. Since TENCH was the next class of diesel boats and was quite similar to BALAO class, I have to conclude that the same sort of information glitches also existed with TENCH boats.

Dpeneding on whose version you read, for example, VOLADOR had high speed motors and reduction gears, low speed direct drive motors, three main engines, four main engines, a dinky, no dinky, 252 battery cells, 504 battery cells, two wells, three wells, a solid cubicle, a split cubicle, a 5" deck gun, no deck gun at all, ad nauseam. Having qualified both silver and gold in VOLADOR, I think my notebooks have the real facts.

This sort of confusion exists with many TENCH boats that were stopped at war's end, then completed in the late 40s as GUPPY-Is or IIs. Again, I'm absolutely persuaded that the best source of reliable information comes from shipyard photography of sea trials immediately following new construction and major overhauls - or from authors who conduct meticulous research and verify their "facts" - ala Jim Christley.

So here are a few questions for you detail buffs -- (TENCH class includes those commissioned as GUPPYs)

1) How many Portsmouth-built TENCH boats were actually commissioned?

2) How many EB-built TENCH boats were actually commissioned?

3) Boston Navy Yard built 4 TENCH boats, but commissioned only 3 - what happened to the 4th boat that was finally commissioned?

4) What other WWII building yard actually delivered TENCH boats into commission? How many?

Thanks Gentlemen!!!

You guys never let me down and I am always amazed by the amount of information you guys possess.

My research shows there were 29 Tench class submarines commissioned.......

1...Portsmouth built 24 + completed SS-524 from Boston.

2...EB built one---SS-435

3...SS-524 was sent to Portsmouth for completion and commissioning.

4...None....SS-425 & SS-426 were Balao class  which were built at Cramp Shipbuilding Co.

>>>...None....SS-425 & SS-426 were Balao class  which were built at Cramp Shipbuilding Co.

Glad to see that someone is checking the facts! You win the golden rivet for the week. Those two were the post-SS-417 hull number, non-TENCH gotchas!