I had to do that with my prior boat -- could not release the forestay due to a below-deck attachment. Could not gain access to the cotter pin that secured the clevis. After about two hours of cursing and trying to bend/twist my wrist into positions it would not go, and dropping two pliers into the inaccessible space under the bow, I said "*&*# it!" and got out the 4" hole saw. Problem solved. I sealed the edges of the hole and installed a plastic inspection port cover the next day.