Question

Before dawn on August 8th 1813, two American merchant schooners capsized in a sudden summer squall. The two vessels, the Hamilton and the Scourge, had been converted to warships at the beginning of the War of 1812.  The site was discovered in 1973. The shipwrecks are 1,640 feet apart at 299 feet below the surface of Lake Ontario 6.5 miles off Port Dalhousie. Both are intact, and somewhat upright with decks strewn with artifacts such as boarding pikes, blocks and cutlasses. Calculate the absolute pressure (Pa) on the top of the vessels. Lake Ontario is a fresh water lake (although winter road salt is increasing the salinity of the Great Lakes).

Answer 1

Given,

The distance between the shipwrecks, d=1640 ft=499.87 m

The depth of the shipwrecks, h=299 ft=91.14 m

The lake is a freshwater lake.

The density of the freshwater is ρ=1000 kg/m³

Let us assume that the atmospheric pressure at the surface of the lake is P_atm=1 atm =1.01×10⁵ atm

The absolute pressure on the vessels is given by,

`P_{\text{abs}}=\rho gh+P_(atm)`

Where g is the acceleration due to gravity.

On substituting the known values,

`\begin{gathered} P_{\text{abs}}=1000*9.8*91.14+1.01*10^5 \\ =994.17*10^3\text{ Pa} \\ =994.17\text{ kPa} \end{gathered}`

Thus the absolute pressure on the vessels is 994.17 kPa.