The very reason that I said I had foam (1/2" thick) wrapped around the pipe where it goes through the bulkhead is to prevent loading and vibration. Also as I said in my post there is hose at each end of the pipe so as to not have a rigid system. These precautions were given by Peggy Hall, who is not an advocate, but did give instructions on how to install it. She's big on regulations, so I would assume that if ABYC said not to use it she wouldn't tell you how, she would quote the reg. I'm not willing to pay the money to get it from the horses mouth though. Does anybody have the actual ABYC section? Has a surveyor told you PVC is inappropriate?
Here is her article on myth and folklore.
http://www.boatbuilding.com/article.php/MarineSanitationFactvsFolklore
Many sources say that PVC can be used, Dashews, Kanter, our local MSD shop say they typically use PVC.
I can see the argument that you don't want to worry about leaks and that running new hose every few years is preferable. I didn't want to have to worry about the boat gradually smelling worse until I finally had to pull all the hoses out. If I have followed the precautions correctly I shouldn't have to do anything to my system except change out the short coupling hoses, which I'm much more likely to do as they are easy to get to. The whole point of PVC is to not have to deal with it for many years. If you have hose that has to be replaced every few years then it needs to be easy to get out and put in. PVC theoretically is a permanent install so easy access does not need to be on the high end of the priority list, though I've done what I can to make it accessable.
As for the repair issue, I guess if I'm on a passage and a pipe cracks in half, I'm stuck with the bucket, most anywhere else I'll head off to the hardware store.
As for winterizing, if it's that much more work to clear out the pipe than winterizing the head and holding tank I'd have put more thought into the routing or put a drain plug in a low spot. If we had a serious cold snap where I would worry about serious winterizing, I would just pull the hose off at the head. On mine there is a short vertical section near the head, the rest is downhill into the tank.
Also I made a mistake in my first post, I said schedule 40, I meant schedule 80.
If you're only comfortable with hose, fine, that's why I presented that there are pundits that give reasons for not using PVC, but I did some research on this before I put it in, admittedly I did not buy the ABYC section on heads, but I didn't read about nor did anybody say anything about ABYC, surveyors, insurers, or boat de-valuation.
John, who might be eating his words on PVC in 5 years.