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@Will Gilmore I"m a little confused about what happened.
There is no main stay on a boat. There is a forestay, a back stay, cap shrouds (or uppers), and lower shrouds.
If the forestay failed, the mast might well come down depending on the conditions. If the clevis pin in the backstay fell out, the combination of the the topping lift and mainsheet should support the mast well enough to keep the mast up if they mainsheet is tight enough.
If you have roller furling and the jib is in place the jib halyard and jib should support the mast.
If indeed the mast fell down, then before worrying about buying an expensive hydraulic backstay adjuster, the rig and mast need to be carefully inspected for damage as well as the deck and hull structure.
This is a good time to call your insurance company and inform them. They will help you assess the damage and determine the best course of action.
Dan at
Rigging Only in Fairhaven MA is a knowledgeable rigger talking to him might also prove fruitful.