Mercruiser 5.0 ignition coil cracks

[Bayliner Bill]

I have a 2002 Mercruiser 5.0 Alpha engine. Recently while cruising at about 25mph I heard a loud metal tearing sound. Boat stopped and would not start. Found no spark and replaced coil which I found was cracked on the negative terminal side. Replaced coil with a new one and after a few hours it did the same. Another crack. Any ideas or suggestions?
Thanks

[redtech]

check the charging system to much voltage can cook the coil

[Bayliner Bill]

Thanks, I will check it.