90hp FourStroke on 181 Mako Bayshark

[Aaron Lariscy]

Looking to see if I am running the correct prop on my boat, right now it has a 13-1/8 16p stainless prop and with the boat loaded to fish it takes 2 to 2-1/.2 boat lengths to get on plane and has a top speed of about 34mph at 6200rpm WOT. To me it seems hard to plane out and kinda slow at speed but I am new to larger boats having only owned small jons in the past.

 

[mpsyamaha]

Re: 90hp FourStroke on 181 Mako Bayshark

34 seems slow for wot speed... what engine do you have on there, a mercury four stroke? What kind of prop is on it now?

 

[WIMUSKY]

Re: 90hp FourStroke on 181 Mako Bayshark

What's the rated WOT rpm for that 90? I could be wrong, but 6200rpm sounds a little high....... You may be under-propped which would hurt your top end.... 4 strokes aren't noted for their hole shots... What's the hp rating for that hull?

 

[jestor68]

Re: 90hp FourStroke on 181 Mako Bayshark

WOT rpm range is 5K-6K. Your Mako has a 20 degree dead rise, which puts it into the deep V category, which explains the time to plane.

I assume you're running a Mercury Vengeance prop, as that's the only SS Mercury prop available for your motor in a 16 pitch. The only other one is the Laser, whose minimum pitch is 19.

The Mercury prop selector says to run either a Laser or Vengeance in 19 pitch, using your current performance. It says you should get 40-41 mph @ 5500 rpm.

 

[Aaron Lariscy]

Re: 90hp FourStroke on 181 Mako Bayshark

WOT rpm range is 5K-6K. Your Mako has a 20 degree dead rise, which puts it into the deep V category, which explains the time to plane.

I assume you're running a Mercury Vengeance prop, as that's the only SS Mercury prop available for your motor in a 16 pitch. The only other one is the Laser, whose minimum pitch is 19.

The Mercury prop selector says to run either a Laser or Vengeance in 19 pitch, using your current performance. It says you should get 40-41 mph @ 5500 rpm. View attachment 194518

Sooo basically I should go to a 19 pitch prop and look into some trim tabs if I want a faster holeshot? What if I were to go with an aluminum prop the stainless ones are costly...

 

[jestor68]

Re: 90hp FourStroke on 181 Mako Bayshark

Sure; the aluminum 19 was on the list too. But for the most bang for the buck, I'd suggest either a Solas or Turning Point aluminum prop for the latest design and casting technology.

And one these will get you on plane in about half the time; for $ 38 the last time I checked. It's called a Doel Fin.