Goshawk joined the stable of insurers returning to profit despite a hefty increase in its 11 September losses.
Its gross exposure to the disasters soared to £77.6m from its previously notified figure of £19.2m, with net losses rising to £18.4m from a previously reported £11m.
But pre-tax profit increased to £4.3m in the first six months of 2002, from a loss of £300,000 last year.
The improvement came on the back of a 134% increase in total gross premiums written, to £204.5m at Syndicate 102 and £36.4m in the group's new Bermudian operation, Goshawk Re.
The group's combined ratio was 90%, with its London business improving to 95% from 107% last year. The Bermudian operation, which retains much more risk, achieved 72%.
Chief executive Chris Fagan said the increase in WTC losses came as a result of late notifications on Goshawk's marine retrocession book.
Business interruption claims from companies such as ferries and cruise ships had broken through reinsurance protection against original expectations.
He said Goshawk's WTC losses were still lower than many of the group's peers.
"Even with our massive increases we're minuscule," he said.
He planned to increase the group's capital in Bermuda to between $200m and $250m (£127m and £159m) before the year end.