DepthCharge radius - effectiveness

[danurve]

I was floating an idea to increase the effectiveness of a Depth charge later in the war, and perhaps logicaly less effective in early war. Since tweeker lets us edit DepthCharge_zon I would like to know more about MinEF / MaxEF. Radius is 20, what is a maximum that won't cause the game to spazz?

Thanx!

[Von Manteuffel]

I don't know whether this is of any help but......

The British Type D , introduced in 1917, claimed a lethal radius of 21 metres (70 feet )and a severe-damage radius ( sufficient to force a U-Boat to the surface ) of 42 metres (140 feet). It's believed that these figures were greatly exagerrated and based on effectiveness against early submarines, whose pressure hulls were not as robust as their WWII counterparts.

The MarkIII variant of the Type D was still in service up to 1940 claimed a much more realistic "kill radius" of 4.3 metres ( 14 feet ) with a severe damage radius of 8.6 metres ( 28 feet ). Initially filled with TNT, it later used an Amatol charge

The MarkVII, introduced from 1940 claimed to split a 22mm hull at 6.1 metres ( 20 feet ) and inflict severe damage sufficient to cripple a sub and/or forvce it to the surface at 12.2 metres ( 40 feet ). The change to a Minol charge from TNT, in 1942 claimed to increase these radii to a "kill" radius of 7.9 metres ( 26 feet ) and a severe damage radius of 15.8 metres ( 52 feet ) - Tis is odd since Minol was a mixture of 80% Amatol and 20% aluminium powder and was regarded as not being as powerful pound for pound as TNT??????

The Mk VII Heavy had a 150 lb ( 68 kg ) weight attached, which increased its rate of descent from 9.9 fps to 16.8 fps. Both had an initial maximum depth of 300feet, (92 metres) which increased later in the War to 500 feet ( 152 metres)

Of course, such figures can only be averages, or estimations, as they cannot take into account the damping effect water pressure and density at depth can have on the force of an explosion.

depth charges caused a spherical, non-directional explosion. The shock-wave was not, however uniform within the rapidly expanding sphere of gas. That introduces another imponderable- 2 charges exploding at the same distance from a target could have markedly varying effects. The proximity of the exploding charge to "weak spots" - e.g. hatches, torpedo tubes, rudder and propellors would also have an effect on the damage caused.

[CapZap1970]

Maybe I am wrong, but AFAIK a depthcharge beyond 150 m. is pretty much harmless due to pressure. It won't let the explotion wave be as intense as it should be at shallower depths.
CapZap

[Sailor Steve]

There was a depth-charge mod two years ago that reduced lethal radius to 8 meters, which is just about right. It makes it possible to be attacked for hours and still survive. It might be incorporated into the supermods; I don't know.

[danurve]

Actually, all this information has been very helpfull in understanding what the radius settings mean, or affect. And appriciated - thanks!
I think to leave the EF settings be for now, trying radius settings of 10-15 for effect on a test save. With 3 DD's on the hunt it sure dosen't take much to let them know where you are.

[Von Manteuffel]

Please let us know how things go. Even if it's too complex to build-in and allow for all the variables, it would be good to be able to have DCs in the game which use the average kill and damage radii.

Not sure how, in-game, you measure the distance of an exploding DC from your boat.

Oh, another thing I forgot to mention earlier. Detonations below a sub had an added effect as the gasses from the explosion naturally moved towards the surface. Apparently even in the milliseconds of a detonation, this added to the effectiveness. The physics of underwater explosions are mind-boggling, involving the shock-wave, a vacuum, a steam-bubble etc. etc.

Best of luck.

[gimpy117]

Originally Posted by Sailor Steve

There was a depth-charge mod two years ago that reduced lethal radius to 8 meters, which is just about right. It makes it possible to be attacked for hours and still survive. It might be incorporated into the supermods; I don't know.

where might this be found??

[tater]

Dunno about the mod, but it's a trivial fix with S3D. Open the DC zon file, change the max radius from 40m to 8m. Save. (work on a copy, obviously).

Still, no one knows if the detonation depth works?

I tried a few values and cannot see the difference. Sad, because this would be SO useful, at least in the PTO where the japanese set their DCs at either 30m, or 60m until lafter '42 when they added a 90m setting.

tater

Originally Posted by CapZap1970

Maybe I am wrong, but AFAIK a depthcharge beyond 150 m. is pretty much harmless due to pressure. It won't let the explotion wave be as intense as it should be at shallower depths.
CapZap

actually it is just the oposite, due to increased hull pressures the shock wave from the depth charge is even more lethal at deeper depths. i think you are correct in that the shockwave has a much reduced effective range due to the pressure.

[CapZap1970]

Originally Posted by WEBSTER

actually it is just the oposite, due to increased hull pressures the shock wave from the depth charge is even more lethal at deeper depths. i think you are correct in that the shockwave has a much reduced effective range due to the pressure.

Thanks for the info, WEBSTER!!!
I didn't think about that!!
CapZap

[Sailor Steve]

Estimates varied a lot on what it would take to sink a submarine, but by war's end they were convinced that the real numbers were about 25 feet (8 meters) to crack a pressure hull and 50 feet to cause damage. Outside of that they were pretty much useless except for harassment purposes.
http://www.navweaps.com/Weapons/WAMBR_ASW.htm

[johnno74]

Originally Posted by WEBSTER

actually it is just the oposite, due to increased hull pressures the shock wave from the depth charge is even more lethal at deeper depths. i think you are correct in that the shockwave has a much reduced effective range due to the pressure.

Hmm, I read in "A diary of a u-boat commander" that the deeper you were, the closer the depth charge had to be to you to do any damage.

[ichso]

But the deeper you are, the more vulnerable you are to damage too.