Burst Struts
I can't say for sure, but my first insinct would be water intrusion over the winter. They filled with water, froze, and burst. I've had similar issues with stanchions. While they didn't burst, they did push a plastic center core up into the lifelines. It's amazing the amount of pressure that freezing, expanding water can create. When you install the new struts, I'd look to see if they have some sort of drain hole towards the bottom. If not, I'd start drilling. That's what I did on the stanchions.Landsend - the struts are supports on the newer trailerable boats that support the mast near the base and facilitate stepping the mast.T J Furstenau