Until around the mid-1950s, when modern composite sailcloth became widely used, the sails for Bermuda rigs were constructed using Egyptian cotton and had much shorter lifespans because the camber cut in to the cotton sails would lose its shape quickly. Interestingly, more modern Bermuda rigs use two independent backstays to make room for a "square head" main sail which has four sides, as opposed to a "pin head" sail which has three sides, as such a sail plan performs better. Many modern "square head" Bermuda rig main sails closely resemble the outline of some junk sails.
Prior to the mid-1950s, Bermuda rigs used cotton sails that were prone to losing their shape quickly due to camber cuts. Modern Bermuda rigs use two backstays for a square head main sail with four sides, which outperforms the pin head sail's three sides. Many modern "square head" Bermuda rig sails resemble junk sails in their shape.