seacock intallation

Hi guys,
I have a new/old question. I have to replace one of my thruhulls and I'm having an argument with a friend, a Triton owner. I was going to buy a flanged seacock and thru bolt it through the hull like the book says to.
My friend says this is not only unnecessary but adds 3 holes in the hull for water to make its way in and 3 bolts to corrode and eventually let water in. I can't make up my mind. His way would certainly be easier.
I'd be interested in your opinions on this critical issue.

Thanks

With a backing plate between the seacock and the hull, the holes in the flange can be used with (short) wood screws to help anchor the seacock.

Bill,
Thanks, I guess that's what I'll do.