▁between ▁Stockholm ▁and ▁Marie ham n . ▁In ▁ 1 9 7 2 , ▁Pr ins ess ans ▁sister ▁ship ▁MS ▁O lav ▁was ▁bought ▁and ▁renamed ▁MS ▁Baron ess an . ▁In ▁ 1 9 7 3 ▁Bir ka ▁started ▁traffic ▁on ▁the ▁routes ▁Stockholm – H els ink i ▁with ▁MS ▁Free port ▁and ▁Stockholm – H els ink i – L ening rad ▁with ▁MS ▁Dro tt ningen . ▁However , ▁due ▁to ▁rising ▁fuel ▁costs ▁and ▁the ▁high ▁fuel ▁consumption ▁of ▁the ▁Free port , ▁both ▁lines ▁were ▁terminated ▁in ▁late ▁ 1 9 7 3 . ▁The ▁Free port ▁was ▁sold ▁to ▁R eder i ▁AB ▁S ve a ▁and ▁the ▁Dro tt ningen ▁returned ▁to ▁her ▁own ers ▁S J . ▁The ▁company ▁continued ▁operating ▁with ▁the ▁Pr ins ess an ▁and ▁Baron ess an ▁until ▁ 1 9 7 8 . ▁The ▁first ▁Pr ins ess an ▁was ▁renamed ▁Pr insen ▁to ▁free ▁the ▁name ▁for ▁a ▁newer ▁ship , ▁MS ▁Finn h ans a ▁that ▁was ▁purchased ▁from ▁Finn lines ▁in ▁January ▁ 1 9 7 8 ▁and ▁renamed ▁MS ▁Pr ins ess an . ▁In ▁ 1 9 8 0 ▁the ▁Baron ess an ▁was ▁sold ▁to ▁Pan am ian ▁interests . ▁ ▁On ▁April ▁ 2 2 , ▁ 1 9 8 6 , ▁Bir ka ' s ▁first ▁new building ▁MS ▁Bir ka ▁Princess ▁was ▁delivered ▁from ▁the ▁Val met ▁V u osa ari ▁ship yard ▁in ▁Hels ink i . ▁With