If you are master of a yacht (based on your username) then I believe none of your time counts because yachts are outside of the STCW. I ran a yacht of almost 2000grt and when renewing my license, credit of that seatime towards renewal on my STCW all of it was denied because the vessel was both uninspected and not SOLAS. This despite the fact that based on the vessel’s tonnage, all the crew was required to be certified mariners.
If you are on an inspected small passenger vessel even if not SOLAS certified, I believe the NMC would credit the time towards renewal of your STCW certificate.
I still don’t know if the USCG gives any credit towards renewal of STCW certificates for service on other uninspected vessels such as any fishing vessel including processors or tugs since those mariners do not need to have STCW certificates to sail? My thought is that that time also would not count. Maybe someone else here can answer that.