In March 1986, the Finnish diesel-electric icebreaker Otso was put through a series of tests in the Bothnian Bay to evaluate her icebreaking capability. This 13-minute documentary produced by Wärtsilä shows how the vessel was, among other trials, rammed into a 20-metre thick pressure ridge at full speed and beat the more powerful 1970s quad-screw icebreaker Sisu in the famous "horse race" through the ice.
Today Otso and her nearly-identical sister ship Kontio are operated by the state-owned shipping company Arctia. They are typically the first icebreakers to be deployed as the icebreaking season begins. In addition, Otso is usually the first vessel to be tested at Aker Arctic's ice model test laboratory after longer service breaks to confirm full-scale correlation.
You can find more information about the vessel here:
arctia.fi/en/ship/otso/
en.wikipedia.org/wiki/Otso_(i...)
This video was digitized from a Betamax cassette found in our archive. Unfortunately we had to remove about 30 seconds of the soundtrack due to a third-party copyright claim for the background music and we have no way to prove that (if) it was used with permission after all this time. However, we decided to keep the footage, so there's a short silent part.