Help. My metal exhaust pipe( flexable hose to stern) seems to be rotting away from the inside,it has small pin holes down the bottom end where it goes through the stern. Has anybody else had this problem and what was their remedy. Frodo

Not sure I have noticed that mine is rusting on the outside (outside of the boat)but the rest looks pretty sound.
These boats are getting on a bit now so I guess this may be cropping up, that part of the exhaust is just one large assembly isnt it?