Aut cum scuto aut in scuto
It sucks all the water out?
If the ladder is made of pure iron / wrought iron, there is a good chance it hasn't corroded. It is the carbon leaching which is the actual corrosion. An interesting example is years ago when researchers were raising one of the Civil War ships, they needed to remove the ramming spar - the three-lobed retainer nut was simply unthreaded.