18 hp explorer

[mdimat]

have 18 HP explorer with 150 optimax, 5.5 powerlift manual jack plate,adjusted it up quarter inch, 5100 rpm WOT, speed 55, water pressure 22, my rpms should be between 5250-5470, not even close to that, should get 58-60 mph,, 23 pitch tempest ss prop any ideas

 

[mdimat]

thanks

 

[Texasmark]

Go to this site: http://www.go-fast.com/Prop_Slip_Calculator.htm. Plug in your numbers and solve for "prop slip". What's your number? For gear ratio, just put in the number, like if it's 1.64:1 just use 1.64 in the box.

 

[Sea Rider]

Or repitch current prop to 22 to run at 5300 revs or to 21 pitch to run at 5500 rpm at wot, if the Pitch Rule of Thumb applies 100%. Only possible to check that on a water trial under current load and preferably on flat calm no wind water cond.

Happy Boating