fire bath

 I've used these firebaths for years.  First, put a solid rock under each bottom corner of the cast iron bathtub so it's propped up nicely with about 10-12 inches clearance underneath. Then fill in the   space, creating a little rock wall with an opening on the side  where you'd like to feed the fire.. Really stabilise it by propping up a 2 by 4 at each corner,  straight from the ground up to the  under- rim  of the tub. Good to figure out where the drain will run out beforehand and have a  pipe in place from the bathtub drain, so that water isn't running all over, and into the fire, when you pull the plug. (- have a string or chain on that plug! groping in the dark for a pulled out plug  while your hot water is gushing out  is a drag) And as far as avoiding smoke; Make the fire  in the afternoon, about 3 hours ( in this weather) before you see yourself wanting to  climb into it.  That way you'll have a steamy hot tub with just a pile  of red embers underneath, not  smelly flames. I enjoy using up crap wood and beach wood  under the tub, so it's not consuming  my firewood stash, too... A starry nightime sky, a cold  glass of white wine sittin' on a stump next to the tub, Ah! .. Heavenly Luxury!