The problem with most of these stories, is they are about grounded masts. Except for some early boats, beach cats do not have grounded masts. Beach cats are less likely to be directly struck by lightning than grounded masts and will be more likely to shock you due to nearby strikes or static buildup.

I have only seen one beach cat struck by lightning. It was setting on the beach during a really bad storm. It looked like someone had set off a stick of dynamite under the mast. The lightning apparently hit the mast, burned through one or more shrouds and grounded itself by vaporizing part of one hull. So if you ever get really unlucky, the results could be really bad.