Spot earnings of product tankers have surged to all-time high levels with a record number of vessels tied up in congestion and floating storage, according to market sources.

Kpler data showed 177 ships were used to store 46.6m barrels of clean petroleum products globally as of Wednesday, the largest amount ever recorded.

While industry estimates suggest dozens of ships have become floating storage facilities for contango play and logistics reasons, many vessels simply face severe port congestion due to brimming tanks onshore.