This PW article:
https://worldradiohistory.com/UK/Pra...01983%2001.pdf
Describes a sand filled dummy load, in the article the resistors are mounted vertically and a diagram is given to specifically immerse the resistors to a half way depth.
I still have mine built in 1983 and was building another recently but it puzzled me then, and still does now, as to why the article specified only to cover half the resistor body.
Any Ideas?
Pete