John, I don't think anyone wants to correct you, just guide in the right direction with all good intentions, take your above line for instance you mention total tonnage as gross, whereas if you want to be technically correct then total tonnage is 'Displacement tonnage' which I think has already been mentioned.
As observed earlier there are minimum 22 pages in sequence in Business and Law for the Shipmaster devoted to tonnage, plus other references, then there is further information in 'Chartering and Shipping Terms' which covers other aspects, not to mention 'Handy Guide to Stowage' which covers other aspects of tonnage applied by different countries, it is a minefield for legal and carriage/dues/Customs purposes and it is not something to be learnt in five minutes.
Because people quote Gross and Nett tonnages for Canal passages, there are other things such as 'exempted spaces' which vary from vessel to vessel which have to be taken into consideration when quoting Gross or Nett.
:Sinking: See what you've started Frank!