Were these boats tied down in any way (even to their trailers)?

They are definitely known to fly, especially in T-storms. This site has carried many such story through the years.

There are clubs that require you to anchor your boat to the ground in some places more prone to this type of weather. It really sucks to be tied down and have someone else's boat land on yours, because his wasn't tied.

Definitely hate to see this type of damage, especially if it was preventable.

Mike