I am in the market for a new prop for a 2008 Yamaha F90TLR and teh current prop/motor has no markings stating the current DIA/Pitch.
Looking on line there are several different options. How do you know what to buy...

Options are:
Diameter Pitch Rotation Part Number
14 9 R 9411-140-09
14 11 R 9411-140-11
13.75 13 R 9411-138-13
13.5 15 R 9411-135-15
13.25 17 R 9411-133-17
13.2 19 R 9411-132-19
13.2 21 R 9411-132-21
Any suggestions on which to start with. WOT 5500 RPM, boat is a 2008 G3 1860 center console .