CGT for offshore vessels (PSVs, AHTS, PLSVs) and also Tugs

Hi dears,
Does someone knows where or how I can obtain the information of the CGT (compensated gross tonnage) for the offshore vessels? I am mainly looking for the PSVs, AHTS, PLSVs and tugs and I could not find it on any article nor on the OECD website.

Thanks in anticipation for your kind assistance,

Matheus Vilela