Not quite getting to an aggressive boil -

[Ameritoon]

g'day brewers!
I am using converted 50L kegs as my brewing kettles and hot tun, like so many of us do. I recently switched to a Bayou Classic Square Patio Stove. I really like the stability it offers, compared to using my keg/kettle on my Bass Pro Turkey fryer. However, since making this switch, it seems my boils never really get up to a good rolling boil. I use an 8 gallon stock pot, on this same burner, it does.

I have determined is that the height of the keg/kettle from the flame and the conical shape on the bottom is not getting a good heat source. I was wondering if any of y'all have experienced the same, and what you did to resolve this? I was thinking about adding a "collar" around the burner to create a more direct heat source?

 

[Cavpilot2000]

Two things:
1: It isn't necessary at all to get a hard rolling boil - a simmer that just disturbs the surface is just fine. In fact that's normal process for Low-Oxygen Brewing, as the big German breweries (like Weihenstephaner and such) brew low-vigor boils to reduce thermal stress on the wort. It's only necessary if you are relying on a lot of boiloff to hit target gravity.
And a low vigor boil will reduce hops utilization by about 10%, but you can compensate for that easily.

2: If you still want a hard boil, I just picked up a Blichmann Hellfire, and man, that thing breathes FIRE! Very high output.