Re: Converting saltwater boat to freshwater boat?
Good point Dave.
There are many salt water boaters, myself included, who never get our trailer axles wet. Instead we use roller trailers and if the boat has some size to it, a power winch. Nothing is waterproof or rust proof or can be completely flushed/hosed off, including the lights.
But many salt water boaters dunk their trailers. Some don't know any better or believe in "waterproof." Some do it so seldom that it really doesn't matter (4x a year for service or cleaning). Some don't have a choice due to design or boat size and just add the cost of replacing stuff as a cost of boating. So again, learn about your seller. Did he go to the ramp every weekend from April to October and dunk the trailer? If so, plan on replacing it soon or at least the moving parts (bearing axle brakes). it's not a big deal, just a cost to factor in.
Even if he launches dry, the end of the trailer goes under. That cross bar may be galvanized on the outside but its not on the inside. It's not a big deal; mine just collapsed on a 20 year old trailer (launching about 8-10 times a year) and the part was only $80. Springs hubs axle all original because they stay dry. But what is bad is if the last 2-4' of the trailer frame (sides) rusts out. You can weld on a replacement section but that's not the best solution for most people.
Trailers are cheap and easy to fix; consider whether you will be doing a lot of long highway hauls as to whether you need to put the money in it.