550. Lien created by agreement.

There is no lien at common law for any charges other than those already mentioned1. The shipowner has, therefore, at common law no lien for freight not payable on delivery2, for dead freight3, for demurrage4 or damages for detention5, for pilotage or any other charges which the shipper has agreed to pay6, for freight due on previous voyages7 or for any other debts due to the shipowner