Yo ho ho and a bottle of rum – a German software developer is suing the US Navy for allegedly pirating its 3D virtual reality modelling and tracking software BS contact Geo and then illegally distributing it onto hundreds of thousands of computers.

Bitmanagement Software GmbH has filed a lawsuit with the US Court of Federal Claims claiming that the US Navy has been using its software to create an accurate visualisation of a virtual military base without paying for licences for at least two years.

According to the court filing, Bitmanagement worked with the US Navy in 2011 on a pilot programme using the BS contact Geo. The trial was set to go ahead on 38 machines, so the navy paid for 38 licences, each valued at €800 (£667, $880) at the time.

After the pilot ended, Bitmanagement claims that it was led to believe the navy planned a large-scale deployment of the software across its computers in 2013, and would be purchasing additional licences.

The US wanted assurance the software would integrate properly with its machines, so to prove that it worked, Bitmanagement had to remove the control mechanism on its software that prevented it from being pirated and used on other machines without a licence.

The navy eventually decided it would like to deploy the BS Contact Geo software and began negotiating with the developer for numerous licences. However, while the negotiations were ongoing between 2013 to 2015, Bitmanagement says the navy quietly copied the software installed on the 38 machines and replicated it onto hundreds of thousands of other computers without permission.

In the filing, Bitmanagement says its information, including forwarded emails, shows the navy has deployed the software on at least 558,466 computers. It believes the number may actually be far higher as the navy allegedly disabled software that tracks use and duplication in 2014, supposedly after Bitmanagement executives realised what was going on.

If true, the US has violated several aspects of US copyright law. Bitmanagement says it has yet to be compensated, and says the US Navy has admitted to installing the software on multiple machines.

"In communications with Bitmanagement, the government has acknowledged having installed Bitmanagement software on a far greater number of machines than those for which had acquired licences," the plaintiff writes in the court filing.

"By copying, installing and using Bitmanagement software without entering into software licence agreements and paying the required licence fees, the government has wilfully infringed, and on information and belief continues to wilfully infringe, Bitmanagement's exclusive rights under the Copyright Act."