Help!!! New Guy

[donmiller970]

I purchased my first outboard (Mercury Optimax 135) after years of I/O.  The dealer sold the boat to me with a 14 1/4, 21 pitch 3 RH prop.  The engine was sending over revving alarms and so I assumed the prop was NG.  I purchased another, same problem.
I am now told the engine should have a 17 pitch.
Looking to trade 2 practically new 21 pitch props for a 17 pitch prop.  But someone please help me make sure I get the correct one this time.

[Len R]

  Be sure to do a propper test before buying 17's...If you are in fact over reving with 21's you need to go up in pitch...perhaps 23 or 25....The lower the pitch, the higher the RPM's and less top end speed....Higher the pitch, the lower the RPM;s and more top end speed...That is a fact, reguardless of what the dealer told you.....