What is the equation for static head pressure?

• A. .444 X every foot below waterline
• B. 1.0 X depth
• C. 0.5 X depth
• D. 0.25 X depth

Answer: (A)

Static head pressure is the hydrostatic pressure from a vertical column of water at rest, so it increases with depth. The pressure equals the unit weight of the water multiplied by the depth: P = γh. For seawater, the unit weight γ is about 64 lb/ft^3, which converts to roughly 0.444 psi for every foot of depth. Therefore, the static head pressure is about 0.444 times the depth in feet below the waterline. That’s why the correct expression is 0.444 × depth. The other options imply incorrect per-foot pressure values and don’t match the hydrostatic relationship.