Tank Boot?

[Henryville]

I think your question was more on singles, but just wanted to mention that on the larger tanks when doubled up the boots become an entanglement hazard because they usually abut one another, quite firmly. A piece of line can get wedged in there pretty tight and it's not an easy place to reach.

 

[rgbmatt]

Bootless tanks feel more streamlined while swimming (probably just my imagination at work).

I have a boot on only one of my tanks - an old non-galvanized 72. The thing rusts in 5 seconds if the paint gets scratched, so the bottom needs all the protection it can get. Otherwise, I don't use them and I don't see many other local divers doing so either. A lot of the old steel tanks you see around town have nice brown rings around the bottoms where the boot used to be - something I'd rather avoid on my own gear!

I've never had trouble putting the backpack on a bootless tank. Just lean it against your knees, and lay it down after you're done with it.

 

[Tom Winters]

Those round tank holders - you're talking about the sawed-off pieces of PVC sewer pipe? You think getting an aluminum 80 with a tank is a tough fit, try pulling an LP 121 or a squatty-body HP80 out of one.
Those things were ok in the days where everyone on the boat used 7.25" tanks, but they're royal pains for 8" tanks. I'd even take Roll-Controls over them, as much as I don't like those either.
Anyway, if someone takes you out on their boat, it's a courtesy to have tank boots. Commercial boats, it's a nicety that most captains appreciate.
And none of that John Wayne-tank-over-the-head stuff either!