Otto Marine has started arbitration proceedings against Robert Knutzen Shipholdings Ltd (RKSL) over two unpaid bareboat charters.

The Singaporean owner said the case stems from two contracts signed between Otto and RKSL on 15 January 2009.

Under the agreement, RKSL took delivery and operated the two ships but it has been in default of the charters, which are worth $2.8m.

Otto said Robert Knutzen is the personal guarantor of RKSL’s obligations and added that legal action may also turn against him.

Knutzen,