In the years before WWII, the French Navy experimented with some pretty strange submarines-like the SURCOUF. It was a huge submarine, and had two 8" naval guns in a watertight turret in front of the sail. It also carried a seaplane, in a waterproof hanger. Whta was the idea with this? Was a sub equipped with big guns a useful warship? I suppose a sub (being low in the water) would present a poor target. But aimimg those 8" guns-how would a submarine be able to stay on the surface long enough to avoid being hit?
I like the seaplane though-what if the sub had to dive while the plane was in the air?
All in all a curious ship-how many were built? and, did these subs ever see action?
Big guns for coastal bombardment–today, we’d use cruise missiles.
The Wiki article has much useful information.
Back in the old days (right after WW1), several of the naval powers tinkered with the idea of using a “cruiser submarine” instead of the “torpedo boat” submarine that we typically think of.
The British had the X-1 and the M class prototypes, built in the mid 20’s. (The X-1 had two dual 5inch gun turrets on board, and the M class had a 12inch gun on board. M-1 was lost in a collision in 1925, and M-2 and M-3 were converted to other types (minelayer and seaplane hangar sub).) None of those served in WW2, IIRC.
The Americans had the Argonaut and the Nautilus (with two 6inch deck guns), both built in the early 30’s, and which served in WW2, although in modified form.
The French, as you mention, had the Surcouf.
The idea behind a cruiser-submarine is that:
- It can outgun any small convoy escorts;
- Guns have better range than torpedoes;
- Can carry more gun ammo than torp reloads aboard the sub.
It turns out that subs make somewhat poor gun platforms for the larger caliber guns.
With the gun down low near the water like that, you tend to nullify any range advantage, as spotting and correcting the fall of shot requires good visibility, which you may not get with sea spray and gun smoke in your face. The 4 and 5 inch deck guns provide almost as good range as a low mounted 6-8 inch, with a higher rate of fire.
Seaplane carrying subs was an idea that was thought neccessary before ship-mounted radar. Before radar, the only way to find a target was with the Mk1 Mod1 Eyeball. The seaplane was supposed to provide a means of searching a much larger area quickly.
The downside was that the finniky aircraft need a calm (but not flat calm) sea state to take off and land in without damaging the aircraft, and it took up to an hour to unpack or pack up an aircraft, which really is a Pain In The Ass when surprised by the enemy.