: I can't see it significantly harming the roof of the car, assuming
: it's properly painted and not simply bare metal. If it's already
: covered in rust spots, pouring salt water over it wouldn't be a
: good idea, but I doubt you'd be posting about your concern if
: that was the case.

: Considering the sheer amount of salt they pour on the roads prior
: to and during each snowstorm that hits upstate NY that then gets
: directly kicked up onto the undercarriage of our vehicles...

Those of us who live in places that are fit for human habitation (ie it doesn't snow) don't have to contend with salt on the roads and its effect on the underside of cars. :)

It isn't the flat painted surface of the roof that suffers from drips of salty water. The problem is that the salt finds its way into cracks and crevices such as where panels are joined.

Everyone in the group I paddle with carries a couple of old 2 or 2 litre plastic milk bottle full of water to rinse the salt off before loading onto the car. Most of them sit the kayak on a couple of cheap folding camp stools to keep the kayak up out of the sand while they do it.

As well as stopping salt dripping onto the car, it gets rid of sand and grit that might otherwise grind away at the surface of the kayak where it touches the cradles.

It's such a simple procedure, that it seems to be pretty cheap insurance to avoid the risk of rust in the car.

Most of the group paddle glass or kevlar kayaks, so rot is not an issue. :)