not exactly words of encouragement when dealing with a boat (or anything else that needs to keep a threatening environment out) but this was something I did myself and did it on purpose.
Yesterday I talked about uncovering the bronze thru hulls on flirt. today I removed three of them. I tried a couple of different methods.. one of which will require me to do some repairs to her bottom. Needless to say, it is easy to slip when using a right angle grinder.
The best method I have found involved using said grinder to cut off the inside bits as flush to the hull as I can get them. preferably to where I can grind the nut down to non-existence. Once I have done that, I go outside and using a hacksaw blade mounted to a single handle, I quarter the thru hull from the inside out. Once that is done, a hammer and a slender chisel is all I needed to split the bronze apart so I could pull it free. It’s messy, it’s loud, and there is still a chance to damage Flirt.. but it gets the job done.