Sailors in action

[Wustenfuchs]

American version.

[Pirate-Drakk]

Originally Posted by Wustenfuchs

Would water temp affect the setting of the depth charge? A depth charge dropped off the Orkney's had to behave differently from one dropped off Cuba.

Good question!

Because water is an incompressible fluid, the simple answer is NO, temperature will not effect the water pressure.

(Actually there are slight quantum mechanical effects but they are insignificant in comparison with the blast effect area of the bomb and other errors in the manufacturing process.)

However, the temperature of the spring in the detonator mechanism will make a slight difference since cold metal is more rigid then warm metal. Even then, the difference would only be a matter of perhaps 10's of feet which still won't make much of a difference operationally. Generally the depth of the sub wasn't well known anyway, so the depth setting for the charge was half guess work in the first place. The important feature is that the depth of detonation changed with the setting of the pressure sensor.

[Jim O]

Originally Posted by Pirate-Drakk

Good question!

Great answer! Thanks P-D.

[Wustenfuchs]

Thanks Pirate Drakk!!

[Brin]

Hi,

Must have missed the question over temp. and water pressure when reading the previous posts....... sorry.

Pirate-Drakk is correct. For as far as I can remember only the effective depth setting was ever adjusted. There was no adjustments for temperature. That said, the idea was to position the depth charge in the approx. close area of the submarine, so that it was the shock wave from the blast that did the damage. For as P-D stated, for practical purposes water is an incompressible fluid, therefore the shock wave would travel further with less energy loss than in air. So the accuracy did not need to be an absolute.

The effect on the submarine if not directly hit, was to receive shock damage, which would cause pipework to split were not mounted on shock proof fittings. Crew damage would be from effectively being thrown across compartments, so bruises, sprain and fractures were common along with the possibilty of a broken neck if not 'braced' for impact. It would also cause the weak points in the pressure hull to fracture, such as at hull valves. Although most hull valves had backups, these backup valves were not much use if it was the body of the hull valve that was damaged on the seaward side. So any pressuue hull leakage if not immediately stabilised at depth would result in a large intake of seawater, this in turn would dramatically alter the pitch and/or roll and bouyancy of the boat, to the extent that the control surfaces would become useless. Without main propulsion and/or emergency bouyancy applied to the main ballast tanks, the boat would sink until flooding was complete, the flooding was contained and neutral bouyancy achieved or pressure hull implosion occured.

[Pirate-Drakk]

I read an account of a U-boat that was on the surface and an aircraft dropped a depth charge right on top of it (I think it actually bounced off the hull) and exploded right below the U-boat.

The U-boat was lifted out of the water but sustained no serious damage because the force of the shock wave just pushed the U-boat up and around. Such a blast underwater would have smashed the hull like a hammer on an avil. When the anvil is air, it isn't so effective. Such is the nature of incompressible fluids and compressible gasses [air].

It did scare the hell out of the U-boat crew none the less!

[Pirate-Drakk]

Originally Posted by Jim O

Great answer! Thanks P-D.

You're very welcome Jim O! I'm always happy to help out with the physics stuff.

[cyberia]

A 40mm gun crew on the USS Hornet