400 rpm low 90hp mercury

[northshoremb]

I'm 400 rpm low of 6000 for my 2006 Merc Fourstroke. Should I drop 2 in pitch or look for same 15 pitch just smaller diameter blade? I have 13.5" 15 pitch Solas prop. My boats a heavy 19' aluminum fully fishing g rigged 5 deep cycles, tons of gear, full livewell

 

[steelespike]

You would normally just go down 2" in pitch. I'd like to see the wot rpm and gps speed.
How is the overall performance?
Normally diameter just follows the prop design. Sometimes diameter is considered for certain specific problems.
Often as pitch goes down diameter may go up.

 

[Sea Rider]

Going 2 pitch down is a wild guess as you don't know how much rpm will gain going just 1 pitch down, Depending on how heavy is your setup could meet the rule of thumb that states 150-200 + revs per each pitch drop, but that's not exact rocker science. OTOH how heavy is considered "heavy" for that rule to hit the mark.

OEM brand's prop pitches close to each other usually maintains same diam, will need to dial best pitch to achieve what you're aiming for. Could stay with same 15 diam and just play with less pitch to rise revs while at wot. Should achieve better hole shot than before.

Happy Boating