Bulgaria refused tug Istra built by the Czechoslovakian government Gotwald Shipyard according to a CIA report dated 6 October 1953

An item reported that the Czechoslovakian government Gotwald Shipyard at Komarno, Czechoslovakia [nowadays Slovakia] built in 1948 a tug fitted out with a 800hp steam turbine for the Bulgarian government, She was however refused due to defects in hull and turbine and commissioned as the Istra for the Czechoslovakian Danube Control Commission.

Source
The report was published on www.archive.org, document number CIA-RDP80-00810A002300930003-1