What is the net force on a miniature sub hatch at 8.5m depth?

[kiwikahuna]

Homework Statement

A miniature sub is lowered to a depth of 8.5 m in sea water of density 1.03 grams/cc. The interior of the research craft is maintained at 1.0 atm. Find the net force that must be withstood by a 1.5 m diameter hatch which leads to the inside.

Homework Equations

Pressure = density * gravity * height
Pressure = P (atmospheric) + density * gravity * height
Mass = density * area* height

The Attempt at a Solution

Pressure = 101300 + 1030 kg/m^3 (9.81m/s^2) * 8.5m
Once I found the pressure, I multipied it by the area (pi r^2)
The answer I got was wrong and I'm wondering what I did wrong. Please help.

 

[CaptainZappo]

You must consider the pressure on BOTH sides of the hatch.