props

[gim]

Yes.

[WRB]

Just following this thread that started out about a ? about prop pitch, aluminum vs SST and boat speed.

The OP has a stock 17 P aluminum 4 blade prop that came with his 75 hp Merc 4 stroke on a aluminum RT178 boat.

The boat isn’t made for speed as it’s a modified V flat bottom Jon type bass boat. 
Trying increase speed requires a prop designed to run in the water with this type of hull bottom. The stock aluminum 4 blade has the correct Pitch, rake and  cup to run wet a SST prop if equal numbers may add a few mph because it has less flex. The boat is pushing a lot of water instead of running on a small pad surface and that reduces speed.

IMO increasing HP is the obvious method to increase boat speed with possible going up to 18P SST prop.

Tom

[TnRiver46]

6 hours ago, gimruis said:

Yes.

Once she’s on pad start trimming up in small increments and mph and rpm will increase, you can hear it. When it blows out of the water it will rev up , that’s when you’ve trimmed up just barely too much. then go back down just a touch and you’re at the Goldilocks setting of trim 

[Woody B]

Yep, trim it up after you're on plane.  Trimming up is worth 4 to 5 mph and ~5000 rpm on mine.  4500 rpm seems low to me, even without trimming up.   Once again, make sure you're getting full throttle.   

Trimming up increased speed (at least) a couple ways.  It raises the foot of the motor some for less drag.  It also lifts the bow some, resulting in less drag, due to less boat in the water.  

 

 

[slonezp]

About 3x -4x the cost of a custom machined SS prop. Impressive to say the least. The link below the video is not the same as the one that posted

 

https://youtu.be/MNnB_50Z20I?si=msn3bzpmFCtlwPI5