Prop question

[No Bail]

I'm considering buying a used set of counter rotating props as a back up. My current props for my 150 Yami 4 strokes are Yamaha Stainless 14 1/4 x 18. The props for sale are 15 1/4 x 17.

What will these different props that are larger with less pitch do to the RPM's on my engines? It would be nice to have back up props, but I don't want to lug the engines. WOT was around 5600-5800 RPM now.

No Bail............ 1000......... 5.23........ 1.2........... 4.35
......................2000......... 8.51........ 3.8........... 2.23
......................3000........ 14.49....... 8.75......... 1.65
......................3500 RPM...25.66mph..................2.50 mpg
......................4000 ........31.7 ........13.8.......... 2.29
......................5000........ 38.49....... 21.9......... 1.75
......................WOT........ 43.84....... 34 ............1.28
Props.......18 x 14 1/4

[Mooch]

Are the backups the SWS II?

If so they're big props with a lot of blade area. I lost about 700 rpm when I tried one on my single F150. It was the same 15 1/4" x 17" you're looking at.