Complex sentence: The Lembit was pulled out of the water on 21 May 2011, using another exhibit at the same museum-BTS-4 (an armoured recovery vehicle, based on the T-54 tank).
Split into simpler sentences: The Lembit was pulled out of water on 21 May 2011. It was pulled out, using another exhibit at the same museum-BTS-4 (an armoured recovery vehicle, based on the T-54 tank).