About unguided torpedoes (addendum)


I wrote about unguided torpedoes kinetics in 2013, and after a couple years it dawned on me that I had missed an explanation for the use of early torpedoes on capital ships.

Books about Pre-Dreadnought and Dreadnought ships as well as armoured cruisers usually do not appreciate their torpedo armament as essential, I've even seen it called "useless" in subject-specialized books.

Those warships of the roughly 1890...1910 era did indeed have a torpedo armament that was unlike the torpedo armaments used later, or on light warships and boats. They used fixed underwater torpedo tubes, facing port, starboard, bow and possibly aft, though not always in all these directions. The torpedoes had an abysmal propulsion, light weight, small diameter, small warhead, contact fuse and an abysmal range.

They were typically only a few knots faster than the ship itself and ran for a few hundred metres only.

You can find data on such torpedoes here:


The archetype was the Whitehead torpedo, so let's look at the Royal Navy's model of the 1890's:

It had about 700 m range at 26.5 kts mobility and a 59 kg TNT equivalent warhead with impact fuse.

So why were they installed, and quite often so?

My opinion is that you can actually see by looking at for example the most iconic capital ship of that period in question:


HMS Dreadnought

Do you see the bow? It's no clipper bow by far, clearly not optimized for seaworthiness. It's a ramming bow, with a protrusion below the waterline like ancient Trieres had.

Now imagine one such ship trying to ram another (in case of the Dreadnought, such a scenario would be a night or foggy scenario, for it was meant to fight at long distances instead).

The targeted ship would typically be able to dodge such an attack unless it's already crippled. So during the dodging the two ships pass very closely past each other. THAT is when the port or starboard torpedoes could be used by both the attacker and defender. They would act as deterrent, even in small quantity and with a small warhead (which would not face much in terms of underwater protection against torpedoes in that period).

The forward-facing torpedo tube could be used to shoot at one possible dodging route of the targeted ship before the captain of the attacking ship steers to strike on an alternative other dodging route.

The rear-facing stern torpedo tube could be used by a ship running away from a dodging attempt, shooting at the pursuer as the pursuer cannot reach it with a torpedo.

Now why were torpedoes mounted below the waterline with all the complications this causes? Later era warships (1920's and later) installed torpedoes on the top deck, same as the torpedo boats of the 1890...1910 period.

The reason was probably that the top deck was simply too high. I have no data on this for the ship-mounted torpedoes, but some early aircraft-launched torpedoes (dropped from up to 30 m altitude) needed about 400 m to level to the correct depth. Let's assume a torpedo launched from a battleship would be stable on the preset depth after 200 m. That might very well be a longer distance than to the target during one missed ramming attempt. The correct depth was important for two reasons:

(1) too deep means no hit whatsoever, for the torpedoes of that time had contact fuses, not magnetic influence fuses

(2) too shallow means that the water pressure at the (small) hole in the hull would be rather small. The water would flow into the target ship much more slowly, and the sailors would have more time for easier countermeasures.

Torpedoes eventually gained much better mobility in the 1904-1910 timeframe, but they were very expensive munitions (kind of like really expensive missiles today; battery-electric torpedoes of the late 1930's were the first quite affordable torpedoes). The shipbuilding practices of the great powers did not adapt to this immediately, and they kept using the old underwater torpedo tube arrangements into the First World War.

A LOT more about unguided torpedoes (though not this above) can be found here:





  1. I have a question about naval armor. Why it disappeared? In land and aerial warfare (helicopters included), armor is even more prevalent than WW2 times but ships went to the opposite direction despite being less constrained by weight and size.

    1. Thick steel armor plating is extremely expensive and extremely heavy. The battleships of the world wars were mostly only well-protected in the citadel; munition magazines, boiler rooms, engine rooms and main artillery turret fronts were protected against heavy calibres at certain distances (not too close, not too distant). Only the conning tower (combat bridge) was well-protected as well, the rest was soft or had thin armour plating only.
      Some of the best-protected battleships (British PoW, Japanese Yamato adn Musashi) were sunk despite their armour.
      Nukes made armour pointless, and even the 1970's and 1980's designs had little use for thick armour for good reasons.
      The critical systems aren't so much the magazines or main guns; it's the radars, fire control, missile launchers - all of which couldn't be protected because it had to be on the outside (VLS can now be protected, though).

      Nowadays passive protection is more about avoiding/controlling secondary fires, limit flooding and some fragmentation protection.

      The rise of Kevlar offered the ability to add some weight-efficient fragmentation protection so missiles stopped by CIWS would not damage the ship much with their broken-up fragments even if the missile was destroyed only 200...50 m away from the ship. Another concern was to limit the effect of fragmentation from anti-radar missiles, which may be Mach 4 fast (+ no active radar emission) and very difficult to stop. An accident with Shrike missiles once disabled an American warship's air defence capabilities for a while, so navies now pay attention to this threat.

      BTW, aircraft of today don't use more armour than during WW2, you were wrong on this. Some attack helicopters are partially protected (the crew only from few angles) against 14.5 mm API at some distance and 23 mm HEI, even some utility helicopters have few parts secured against 14.5 mm API at some distance, but combat aircraft other than Su-25 and A-10 have no armour worth mentioning.

      There's sometimes a ballistic plate between engines so catastrophic failure of one engine doesn't stop the other, and that's usually about it. Fuel tanks aren't self-sealing any more, though the kerosene may have additives that limit fire hazards and the air in partially drained fuel tanks is not an explosive kerosene vapour-oxygen mixture. The often double vertical stabilizers add some redundancy, and flight control is 3x or 4x redundant.

      Back in WW2 fighters usually had an armoured oil cooler, armoured backrest (or armoured glass behind the pilot's head, armoured windscreen (up to 60 mm thick), self-sealing fuel tanks and often 4...10 mm armour plating in other critical areas. Dedicated bomber destroers with 30 mm guns sometimes had extra armour plating, as had some ground attack versions of fighters (Fw 190F example).

      Nowadays a single 23 mm HEI hit could bring down a F-22 or Typhoon from almost any angle.

    2. Thank you for the correction on aircraft armor. I was thinking about helicopter armor. I probably gave helicopters too much credit in hardness.