In my opinion the blue/green/Sanman bowl is not creekside equipiment, but instead a job done at home at your pace with additional accessories such as a cold beer. To get the bowls to work efficiently they must be set up correctly, which can be time consuming, and the material must be classified well. This time could be much better spent finding gold.
The cold beer is meant as a refreshment for the handler of the bowl.
Using beer in bowl can cuase foaming, and elevation of material, thus
possibly leading to the loss of precious metals.
Consuming too many beers could cuase sudden lapse of balance cuasing
said handler to become dizzy from watching water go round and round in
bowl, which may lead to collapse onto bowl/material leading to loss of precious