GulfMark Offshore Inc., Houston, (NYSE: GLF) has named James (Jay) Harkness vice president, investor relations and treasurer. He was chief financial officer of Rigdon Marine Corp.

Nathan Guice has been named vice president, business development. He was vice president, operations, for Rigdon Marine and manager of domestic marketing and sales for Tidewater Inc.

Darrel Plaisance has been named vice president, international operations. He was regional manager, U.S., for GulfMark and vice president, Sea Mar Management LLC.

David Darling has been named vice president, human resources. He was a captain, operations manager and human-resources manager with Zapata Gulf Marine and Tidewater.

William (Billy) Guice has been named vice president, marketing. He was vice president, sales and marketing, with Rigdon.

GulfMark provides worldwide marine transportation to the energy industry through a fleet of 93 offshore-support vessels.