UPDATE on the Tear-Drop Submarine Hull from 1864

Background

Eight years ago introduced our M.E. readers to the amazing discovery of The Sub Marine Explorer, in a Tear-Drop Submarine Hull Dates to 1864.   A recent article about the Explorer (photo) has the tear drop hull design of post-WWII German, Russian and U.S. submarines like the Institute of Nautical Archaeology (INA) says [emphasis mine]:

"For the first time, a comprehensive sense of how the submarine was built, how it operated, and the incredible level of sophistication inherent in Julius  Kroehl’s forgotten craft was apparent."

  

Among other innovations, Sub Marine Explorer (photo above) had the tear drop hull design of USS Albacore (1953).  The USS Albacore (AGSS-569) pioneered the American version of the teardrop hull (sometimes referred to as an "Albacore hull") of modern submarines that was derived from extensive hydrodynamic and wind tunnel testing. Well, how did inventor Julius Kroehl arrive at the ideal shape almost a century earlier?

Update

Interested readers are urged to digest the full INA article (linked above). Of particular interest are revelations of some sophisticated Woods Hole Oceanographic Institute studies conducted by Dr. Erich Horgan, Mike Purcell and Greg Packard.

While calling the pearl-diver Explorer a glorified diving bell, some of its detractors are quick to describe the confederate sub (Hunley) as high tech for its time, when actually, it was only a crude device used in a visionary manner by some very courageous volunteers.  While the Explorer's hull may now be beyond economical restoration, the INA article reports that, "technology and characteristics of a rare, surviving example of Civil War-era nautical technology have been preserved through the detailed plans prepared as part of this project".

Hat tip to reader Bear Nyhof for requesting this update.

Submarines are always silent and strange.

The ANSWERS: Q.O.T.W. 11 APR 2014

Background information and photo (s) presented when the Questions of the Week (Q.O.T.W.) answered below were originally posted may be found here: Anti-subD 641marine Q.O.T.W. 11 APR 2014.

Q & A

 1.  An "anti-submarine" vessel is shown transiting a "cut". The nation which launched this ship has no destroyers in its entire navy. What are the ship's nationality and type?  ANS:  The ship is the French navy's (Marine Nationale Française). It is a type F70 "anti-submarine" frigate en route to the Black Sea for Ukraine crises.

2.  What are the name, hull number, and top speed of this ship?  ANS:  MNF Dupleix (D 641) has a top speed of 30 knots.
 
3.  What is its crew complement (officers and men)?  ANS:  20-22 officers and 145 sailors.

4.  With what anti-submarine equipment is this ship armed?  ANS:   • 10 L5 Mod4 torpedoes
• 2  L5 torpedo launchers
• 2 Lynx WG13 Mk.4 helicopters, each with DUAV4 sonar, Rheseda system for acoustic data transmission, and 12 Mark 46 torpedoes

5.  What are the vessel's draft and the canal's mean depth (in feet)?  ANS:  MNF Dupleix's  draft is 19 ft versus the canal's nominal depth of 26 ft.

6.  What is the purpose of that buoy to which the ship appears tied? ANS: What appears to be a buoy in last week's photo is actually a canal tug seen from a head-on perspective.
 
7.  What is the name of the canal and how does its length compare to the Panama Canal?  ANS:  The Corinth Canal's  is 3.9 miles in length (the Panama Canal is 12 times longer at 48).

8.  Did the pictured canal have strategic value in WW2?  ANS:  Yes, serious damage was inflicted on the canal during World War II by both by both British and Nazi forces, when it was twice the scene of fighting due to strategic importance.

9.  This canal has a fairly unusual submarine feature; what is it?  ANS: The Canal has submersible bridges [ YouTube video] at either end. When a vessel approaches, the bridges are  submerged allowing ships to proceed.

Submarines are always silent and strange.