Conversion of Spanish length, weight and space measurements into English length, weight and space measurements ?

Since there is apparently a conversion option for spanish burgos feet to imperial feet...
there is also a conversion of the spanish volume / weight
"toneladas de desplazamiento" in english tons BM?

Based on the misleading information on Wiki/threedecks.org/ etc., the question arises as to whether the information on the Spanish First Rates is partly Spanish toneladas.

If these were different to the same degree as Burgos feet are from imperial feet, the values ​​would make at least some sense.