Shock factor

Shock factor is a commonly used figure of merit for estimating the amount of shock experienced by a naval target from an underwater explosion as a function of explosive charge weight, slant range, and depression angle (between vessel and charge).

${\displaystyle SF={\frac {\sqrt {W}}{R}}{{(1+\sin \phi )} \over 2}}$

• R is the slant range in feet
• W is the equivalent TNT charge weight in pounds = charge weight (lbs) · Relative effectiveness factor
• ${\displaystyle \phi }$ is the depression angle between the hull and warhead.

The application scenario for Equation 1 is illustrated by Figure 1.

The numeric result from computing the shock factor has no physical meaning, but it does provide a value that can be used to estimate the effect of an underwater blast on a vessel. Table 1 describes the effect of an explosion on a vessel for a range of shock factors.

Table 1: Shock Factor Table of Effects

Shock Factor	Damage
< 0.1	Very limited damage. Generally considered insignificant
0.1–0.15	Lighting failures; electrical failures; some pipe leaks; pipe ruptures possible
0.15–0.20	Increase in occurrence of damage above; pipe rupture likely; machinery failures
0.2	General machinery damage
≥ 0.5	Usually considered lethal to a ship