If wind speed conditions of 25 m/s had the effect of waves smashing the passenger ferry windows, it would be happening all the time. As the Captain of Silja Europa and On-Scene-Commander says:
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If the vessel was on its side, it doesn't prove that the reason for sinking was a smashing of windows, in order to fulfil the requirement of 4,500 tonnes of water.
Another similar vessel had a fault with the bow visor and it managed to sail for two and a half hours into port without capsizing despite the thing being open.