Return of the Submarine Gunboat
Kudos to D.E. Reddick, Romanian blogger Resboiu, Alex and others for inspiring this notion!
First, D.E. started the ball rolling with this suggestion:
Recall that the Royal Navy built submarines with major artillery – i.e., 12 inch (305 mm) guns. Those were the M-class, which carried a single gun of that rather large size. Another class of RN submarines embarked with four 5.1″ (130 mm) guns in two twin turrets. Some of the largest USN submarines in service during WW-II carried two 6″ (152 mm) guns. So, what am I getting at? Well, why not mount a 155 mm AGS forward of the sail on a future SSGN? Maybe by then (late 2020s or ’30s) it’ll be an electromagnetic railgun rather than a chemically propelled artillery system. So, let’s consider a future SSGN type which can launch 100 to 200 cruise missiles (hypersonic speed) and also fire several hundred rounds of guided artillery munitions against various targets at lesser ranges (200-500 kilometers, let’s say). If done correctly, only the muzzle of the weapon would break the surface of the water. Just a silly idea, really…
Perhaps not so silly after all, as I will explain. But why the need for guns on a submarine in the first place? For a vessel intended to strike stealthy and silent underneath the surface of the sea, surely its torpedo’s would all important, right? Except in practice, as the craft was used mainly against merchant vessels, the gun became very handy, allowing the raider to save its rather costly and few torpedoes for high value targets. For most of the last world war, the U-boats spent more time on the surface than submerged anyway, mainly because the diesel engines possessed vastly greater range, and because the high surfaced speed allowed them to keep pace with any merchant ships.
The apogee of the gunboat submarine came with the French Surcouf, a fearsome vessel thankfully in the hands of a friendly ally. It is described here by Wikipedia:
Surcouf was designed as an “underwater cruiser“, intended to seek and engage in surface combat. For reconnaissance, she carried a Besson MB.411 observation float plane in a hangar built abaft of the conning tower; for combat, she was armed with eight 550 mm and four 400 mm torpedo tubes and twin 203mm/50 Modèle 1924 guns in a pressure-tight turret forward of the conning tower. The guns were fed from a magazine holding 60 rounds and controlled by a director with a 5 m (16 ft) rangefinder, mounted high enough to view a 11 km (6.8 mi) horizon, and able to fire within three minutes after surfacing. Using her periscopes to direct the fire of her main guns, Surcouf could increase this range to 16 km (9.9 mi); originally an elevating platform was supposed to lift lookouts 15 metres high, but this design was abandoned quickly due to the effect of roll. In theory, the Besson observation plane could be used to direct fire out to the guns’ 24 mi (39 km) maximum range. Anti-aircraft cannon and machine guns were mounted on the top of the hangar.
Surcouf also carried a 4.5 m (15 ft) motorboat, and contained a cargo compartment with fittings to restrain 40 prisoners. The submarine’s fuel tanks were very large; enough fuel for a 10,000-nautical-mile (20,000 km) range and supplies for 90-day patrols could be carried.
Sounds like the ancestor of our Ohio SSGNs which are true underwater battleships! As was said such vessels were few and far between, but consider such a craft in the hands of an unfriendly nation as Resiboiu alludes to:
If Surcouf was in the hands of the Kriegsmarine, I’m sure would be covered in glory by South Atlantic Crusades and even further in the Indian Ocean. I think it was well received and such a different version of “Strike from the sea” by Douglas Reaman. Incidentally, Surcouf in the hands of the Germans could bomb the American and Canadian ports with his heavy guns.
Only one Axis navy used very large submarines to any effect, but these were not gun-centric. The Japanese I-400 were used mainly as “submarine aircraft carriers“, and were not really effective though the concept was at least workable. The 6000 ton monsters carried 3 seaplanes in a hangar but weren’t all that lethal considering the poor bombing tech of the era (hence the need for huge airwings on land and sea). I think a submarine carrier is totally viable today since you have JDAMs assuring you get economy out of the handful of planes/UAVs you can carry.
But to what purpose would be a gun-armed submarine be for this modern era of supersonic missiles and robot aircraft? Though the rail gun against high value targets may be possible, I have a more economical idea. Consider the Dutch Walrus out there off Somalia, spying on the pirates. Perhaps she sees some Somali pirate dhows attempting a hijacking and there is no other ship available. Will she sink a 20 ft or so wooden pirate ship with a $100,000+ torpedo, or a million-dollar missile? So here I could see need for perhaps some retractable, disappearing decks guns on an SSK.
If the USN would grasp hold again of the conventional boats to bolster her falling SSN numbers, she could use such craft also in the Caribbean against smugglers, as it would be more economical than expending costly missiles. Even in a covert amphibious landing, which is an important mission for our SSNs, she may find the need to support Special Forces, provide them cover during an extraction off some Third World coast.
Perhaps not so silly after all D.E., but a back to basics solution to a growing problem!