Well I called the nice folks at Trident Marine
, the manufacturer of the Shield's hose, and spoke to a very nice man who patiently answered my questions.
He confirmed that in fact the VAC XHD hose is comprised of a blend of rigid and flexible PVC that softens around 180F. He couldn't speak as to the softener. If I had to guess it would be phthalates, but who knows.
He seemed to me a little surprised when I questioned whether or not could could damage the hose by limited heating
and commented something to the effect of "Sure, you can heat it up and re-form it, no problem. After all, it's plastic!" which is nice because anybody who ever heated up their coextruded PVC head
hose with hot water or a hair dryer doesn't have to run out and change all their plumbing
in a panic.
He did also seem very surprised when I said I had some success working it with the expander-tool but dispute that it was possible. The hose itself is designed to resist this after all.
I played around with it a little bit today and found that it readily will expand .15" in diameter, but that to go further is difficult without hard spots occurring which result in uneven stretching.
I figure for what it's worth I'll give it a go. I didn't have a caliper the last time I was on the boat, so will have to see what the exact diameter of the flange is. If it is around 1.70" I think it will probably work but is it's closer to 1.75" I am not so sure.
If it doesn't play then I am okay with that, at least I have something to show for my efforts and maybe you do too.
Thanks Trident Marine!