Stephen,
My previous owner had a brass fitting at the raw water strainer.
I found it after I added an inline Groco ball valve (temporary fix) as my raw water seacock is froze open. I started replacing hoses, fittings and servicing my strainer after I installed the ball valve. When I put the wrench to the brass fitting it crushed into many pieces.
It could have sunk my boat.
For those reading that are unaware of brass usage in critical or below waterline applications, brass contains zinc and will become a sacrificial part in the system with loss of life or property as a potential consequence.