They didn,t mentioned how much speed was lost ,but I guess it was very little ,but when they added more torque/horsepower ,the least expect was a little more speed.
but I do also think the gearbox they used with the Yanmar 440,s is the same box I use in my boat with the 1,30 in 1 th gear and 1:1 in second gear,and not sure if ZF offers taller ratio,s than 1:1 ,but I see what you mean with losing prop speed ,and maybe Scotty knows if they were using the 2 speed boxes with the FPT,s or not ? maybe they opt for a single gearbox with a ratio under 1:1 ??? if so the circle is closed