Don't like the old corrugated bilge hose on any through hull fitting that is underwater. The stuff will crack at some point as it gets old. If you remove an old hose, chances are it will split in the process--I have actually had the new stuff crack when installing it on an above the water line blige pump recently---I am wondering where they are sourcing the stuff these days. I took a length of new hose back to Svendsens to show them that the stuff was so thin that it cracked if bent more than 20 degrees--they decided to take it to Trident to see what is going on. For the added cost of sanitary or exhaust hose the risk of fracture simply is not worth it. I am surprised if there is not an ABYC regulation on this--but I am not current.
BTW--on Marlon through hull fittings: I discovered that Ericson used some 90 degree fittings in the Marlon valve that are just poor quality black plastic--not Marlon or nylon. One of them shattered into dozens of pieces when I attempted to turn it out by hand---it was 30 years old, but I was shocked that the material was so brittle I ended up with a handful of plastic chunks. Fortunately, I can wait to my next haulout to fix it. I still like Marlon, but am more cautious about what is put on the valves.
FWIW