Quote:
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The effective radius of the percussive wave depends upon the structural strength of the attacked vessel, and no definite values can be stated. Approximate information indicates that a 600-pound charge may cause moderate damage at 80 feet, but to be fatal it must explode within about 30 feet. The 300-pound charge may prove fatal within 20 feet. It is to be noted that doubling the weight of charge does not double the effective radius.
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The larger IJN Type 2 was 162kg warhead (356.4 lbs).
The above quote says the DC may be lethal at ~20' (6.1m). It also says moderate damage on a much bigger warhead (600lbs) out to 80' (24m). The stock 40m is clearly too far, but it's not as far off as I had imagined. Of course I bet the damage as a function of distance is non-linear in RL. No idea if the game treats it as a linear gradient.
At the min SH4 explosion radius, 100% damage is applied, and to hitpoints as well I believe. So the stock setting of ~4m is not too bad, really. Setting the max radius too low (as I have been testing) is probably too far in the other directions. Looks like the TM value is pretty reasonable.
A quote about British air dropped depth bombs:
Quote:
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In the spring of 1942, a 250-pound depth charge increased effectiveness by 40%. The lethal range to penetrate a U-Boat was an explosion within about nineteen feet (5.8m—tater) of the U-boat.
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Another quote I saw says 40 feet.
Another:
Quote:
At the depth charge's minimum depth setting of 30 feet, the boats had to travel top speed to avoid damage from the blast. They also had to be dropped at least 50 feet apart to avoid setting each other off. The depth charges were only mounted when on patrol. No sense in having a 300lb target of high explosive on deck if not needed. Depending on the area of operation and main targets, many images of PT boats in action show that the racks were commonly removed. Mainly used against submarines, depth charges had to explode fairly close to the sub to be effective. This called for great expertise since, unlike ships and airplanes, the target was unseen (except for slight traces if you were lucky) and the depth vector also had to be considered. It was almost like firing the 20mm at a Zero at night during a lightning storm with bullets that only worked if you had set the right distance to the target. Here is the Navy's estimate of distance from the sub's hull / damage for this type of depth charge:
150-90 feet / Negligible
90-50 feet / Perhaps some (15m to 27m)
50-30 feet / Moderate (9m to 15m)
30-10 feet / Probably fatal (3m to 9m)
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