SeaBright Holdings, which sells workers-compensation insurance to maritime employers and other niche markets, is sailing off into the sunset.

The Seattle-based specialty insurer said late Monday it is being acquired by Enstar Group of Bermuda for $252 million, or $11.11 a share. That’s 34.3 percent above Monday’s closing price of $8.27 a share.

The two companies said they expect the deal to close in the first quarter of 2013.

Enstar specializes in acquiring insurance and reinsurance companies in “run-off” mode — that is, managing existing assets and paying claims but not writing any new policies.

SeaBright, which traces its roots to the Eagle Pacific Insurance division of Services Group of America, went public in January 2005 at $10.50 a share after a series of ownership changes.

While its assets have nearly quintupled since then to $1.1 billion, its core business has struggled in recent years. The company posted net losses in 2010 and 2011, though it reported a $9.5 million profit for this year’s first six months.

The stock peaked in mid-2007 at $19.74, and has been ratcheting lower ever since.

Drew DeSilver: 206-464-3145 or