double barrel concave?

I recently ordered a 6’6"x 19"x 2 1/2 roundtail. I told my shaper that the bottom is up to him,“whatever works” since I don’t know a thing about bottoms.My last board I had was a flat with a slight double concave in the tail.It rode well in all conditions. Well my new board has what he called a double barrel hull, something like that? It appears to have a double concave from the nose all the way through the tail. I’ve only ridden it two days so I can’t really judge it yet,but it seems to be more loose. That could be because of the hips which I’ve never had.I’m just curious if anyone has shaped or rode and of these double barrel concave boards? I think Doc was making these boards for a while? Any info? Thanks!

I shaped a 7/0 x 20 x2 3/4 single fin pintail with a double barrel concave . Ive found it fast very fast and loose. Goes really well.