Back when I got my license, there was no Gas Turbine endorsement. I did, however, take a Gas Turbine elective that was offered. It was a good course. We even made a trip up to the GE plant in Schenectady where they were building the Frame 5 and 7 industrial turbines. Now, I never sailed on any GT powered vessels, but now I handle some GT related claims for offshore installation. Glad I took the course. There are significant differences between Gas and Steam turbines, condensers aside.