Submarine through the Ice Cap
GES 131-008
Fall 2004
Modern submarines can surface through ice three to four feet thick. Assuming a submarine is at
neutral buoyancy just below the bottom of a four-foot thick layer of ice, what percent of the
submarine’s main ballast tanks must a submarine blow for its conning tower to break through the
ice? Model the conning tower as a six-foot diameter circle and the ballast tanks as the 20-footlong space between a 30-foot diameter outer hull and a 25-foot diameter inner hull. Assume that
the force to break the ice is equal to five times the weight of the ice broken. The density of ice is
57.2pcf and the density of sea-water is 64.2pcf.
Locations of Main Ballast Tanks
from http://www.heiszwolf.com/subs/tech/tech01.html
Ballast tank location for
modern submarines
Ltank
Dinner
Vannular = Aannular Ltank
Aannular = Aouter - Ainner
Aouter = pi/4 (Douter)2
Ainner = pi/4 (Dinner)2
Ballast tank is in
annular space between
outer hull and inner hull
Douter
Answer: 14% of the total ballast tank
volume must be blown