Complex sentence: Part of the conversion was the removal of her second funnel, which was in any case a dummy used to ventilate the engine room below; this was done to improve the arc of her Anti-Aircraft Guns.
Split into simpler sentences: Part of the conversion was the removal of her second funnel which was in any case a dummy used to ventilate the engine room below. This was done to improve the arc of her Anti-Aircraft Guns.