Or on the other hand understand, and roll with, plopping them alongside and hoping for the best. PGMs were sketchy even by 1943-45, but breaking plates with hydrodynamic pressure was already fairly well understood, and it allows for near-misses as well as dead-strikes.
A near-miss from a 1000-lb bomb on a battleship might be even better than a direct hit atopdecks. Water isn't compressible until about 30,000 psi, so near-misses on BBs can be useful, insofar as they open up the hull rather than wreck the topsides. Depends on the sitch, no? Water-hammer is a thing.
Except "aiming to miss" is even harder than trying to hit the target. The bomb has to be very close to do any serious damage. For example:-
Standard 250lb Mk.VIII airborne depth charge - contained 170lb of Torpex explosive (50% more powerful than TNT). Its lethal range against a U-boat was 28ft. And that U-boat was going to be close to the surface when the aircraft was dropping these (they were fused to explode at 25ft).
German 1,000kg (2,200lb) AP bomb containing 350lb of TNT that hit Formidable in May 1941, passing through the ship, before exploding underwater, only caused some relatively minor flooding to some stern compartments. It exploded about 40ft from her side. There wasn't a massive hole. It merely dished the plating between the frames causing the rivets to pop so allowing the water in.
The more normal SC 500 (1,100lb) HE weapon used by the Luftwaffe only contained 490lb of explosive.
Illustrious has the same experience both while at Malta in 1941 and then in 1945 with a large bomb from a kamikaze exploding close to her hull. The only noticeable effect from the latter was a vibration through the ship that only became unsustainable at speed (she was already limited to 24 knots before that). It was only when they put divers down after they got to Leyte that the full extent of the damage was found. But there was no flooding. That bomb was estimated at 1,700lb (probably a 800kg weapon used in the D4Y3 kamikaze aircraft) and exploded about 50ft from her side.
Of course the depth of the explosion makes a difference. But the naval architect DK Brown noted that, in relation to torpedo explosions against ships but it seems equally valid for near miss bombs, the effects of underwater explosions were exceptionally variable and difficult to predict (see Nelson to Vanguard).
Major warships (capital ships and aircraft carriers) of the period had extensive torpedo protection systems covering much of their vital length. Layers of side compartments some empty, some liquid filled plus armour plate, designed to absorb the effects of underwater explosions.
Here is a photo of damage to Illustrious in 1941 show the external effects of a near miss. Note the damage is under her armour belt. But she was still able to sail away from Malta to be repaired in the USA.
Britain developed a couple of novel weapons designed to attack the unprotected underside of major warships. The first was the 'B' or Bouyancy Bomb.
Description The bomb consists of a truncated, cone-shaped charge case with a concave nose welded on, a buoyancy chamber secured to the charge case by twelve nuts, and a clip-o
And the second was the 600lb Johnnie Walker Bomb which only seems to have been used on one occasion, unsuccessfully against Tirpitz in Sept 1944.
Helensburgh Heritage Trust
www.helensburgh-heritage.co.uk