Before that, it says:
"ten cubits from brim to brim, round in compass"
Almost ...
1700
Which the detractors take as the OUTER most dimension, which illustrates their point that the writer didn't know his PI from a hole in the ground!
If the material was something less strong as bronze, then the thickness would have been greater than a 'handbeardth', making the outer dimension even greater.
However, anyone would know that it's the INNER dimension that is needed, to hold a certain VOLUMN of liquid.
To say otherwise shows a need to 'prove the bible wrong' for some reason or another.