The Finnish Navy had experience with German Siebel ferries during World War II and partly based the Kala class on their design.

The original requirements also included the ability to break the ships into loads for road transport, with two hull pontoons and dismantled deck structure.

As originally built the Kala class had minimal superstructure with only a small control cabin in the rear and received the nickname "floating telephone booths".

[5] The Helsinki city fire department purchased Kala 3 for oil spill cleanup duties and renamed the vessel Miina.

[6][7] Kala 4 caused concern when it was found in the possession of Airiston Helmi after the company was raided by Finnish police for suspected economic crimes.