In their Pirate Special $2($Nov $28,2007)$ episode the Discovery Channel's Mythbusters experimentally evaluated the feasibility of a scene portrayed in the movie Pirates of the Caribbean: The Curse of the Black Pearl. In the movie Captain Jack Sparrow and Will walk along the bottom of the ocean holding an upturned rowing boat over their heads to trap air, allowing them to breath. Is this possible or a myth$?$ Base your answer on fluid mechanics principles.

The following assumptions can be used:

The rowing boat is a $10ft3ft2ft(LWH)$ rectangle.

The rowing boat is made of pine wood $)=(21\mathrm{.}8l\frac{b}{f}{t}^3$ and weights $150l{b}_m.$

The whole upturned boat is filled with air.

Air has negligible weight.

${}_{\text{s}\text{e}\text{a}\text{w}\text{a}\text{t}\text{e}\text{r}}=64\mathrm{.}0l\frac{b_f}{f}{t}^3$

One other thing $....$

The Olympic record for weightlifting in the $170-lb{b}_m$ men's division is $380lb{m}_m.$ Yet, weight lifters have the weights over their heads for a few seconds only!

$...$ and if you believe the internet $...$

It takes $540N($or $122l{b}_f)$ to rip off a human head from its body. Sorry, could not find the value for an arm!