Changed prop something looks wrong

[Kenneth Hughes]

I have a 1998 Yamaha 150TLRW and I changed the prop which was a 21 pitch. This caused to engine to have to many revs at WOT so I exchanged it for a 24 pitch. After placing the thrust bearing on and then the prop the spline stop just inside the outside of the prop. The previous prop had a half inch spacer then the nut and cotter pin. Can I just put a large washer between the prop and nut?
The thrust washer does not go inside the prop or the foot.

[boats.net]

Sounds like the prop is not hubbed for Yamaha or the first prop had different hub, make sure thrust washers match prop you are using.