Was Calcutta's merchant hull as strong as a fourth rate?

How did HMS Calcutta's hull strength compare with a typical purpose-built fourth rate?

It was about the same in structural strength, though the merchant configuration carried far fewer people and guns.

Calcutta's hull strength was about comparable to that of a typical fourth rate. East Indiamen needed heavy structure for cargo and long ocean voyages, giving such hulls real conversion potential. Calcutta's naval conversion raised her complement from 125 to 324 and added a heavy lower-deck battery. Structural strength alone therefore does not measure the fighting power of the merchant configuration.