The Liebherr BOS series is a family of offshore cranes manufactured by Liebherr-Rostock GmbH, a subsidiary of the Liebherr Group.
The crane family is designed for heavy-lift, maintenance and supply operations on offshore installations and comes in electro-hydraulic, diesel-hydraulic or all-electric configurations.
Liebherr delivered its first BOS crane B10/17 EX in 1975 for installation on the FPSO unit Princess Aweni.
In 2015, the Liebherr plant in Nenzing sold its 1,000th offshore crane. This figure includes both BOS cranes and RL cranes from the Liebherr RL series.
As of November 2025, a total of 502 BOS cranes had been produced and installed worldwide. The United Kingdom, Brazil, and Norway rank among the largest markets.
The BOS crane is a slew-bearing, rope-luffing crane equipped with a lattice boom. It is offered in a range of sizes, with lifting capacities of up to . The crane can be fitted with a boom length of up to 102 metres, meeting the requirements for offshore wind farm installations.
Following a design revision in 2005, the BOS series adopted a configuration that Liebherr now regards as the industry standard; The update introduced a division between the A-frame and the machinery housing, replacing the earlier concept in which the drive system was integrated into the turntable with the A-frame mounted on top.
The series includes multiple models, which are differentiated by their boom length and lifting capacity. The number in the model name represents the overturning moment in ton-metres.