Early British carrier designs allowed tall hangars, with Eagle offering a particularly large height. Later treaty limits encouraged the Royal Navy to reduce hangar height so it could fit more capability into a smaller displacement. Weight carried high above the water required compensating weight lower in the hull to maintain stability. Lower hangars therefore saved more than the weight of the upper structure alone. The benefit was especially relevant to designs with two hangar levels, where reducing height freed weight for other uses.
Notable Point · 36:39-38:21
How hangar height consumed a carrier's weight allowance
Tall early hangars gave way to lower treaty-era designs because reducing weight high in the ship also reduced the ballast needed for stability.