Kristian Siem, founder and longtime leader of Siem Offshore, is stepping down as chairman of the Norwegian offshore support vessel (OSV) firm after reaching a deal to acquire nine vessels in exchange for his 35% stake in the company.The company announced it has reached an "amicable agreement" to sell Siem Barracuda, Siem Stingray, Siem Opal, Siem Pearl, Siem Topaz, Siem Pilot, Siem Pride