Oversized 4blade prop equals poor performance. Questions

803803 Posts: 175 Officer
I have a 17ft flats boat pushed by a (2006) 90 2stroke Yamaha. The previous owner put a large PowerTech 4 blade 15 pitch stainless prop. Cruising it burns very little gas at around 3500 rpms (30 mph) but only gets to about 35 mph at 4800 rpms. Boat is also very sluggish in acceleration. It accelerates to around 3000 rpms and slowly gets on plane then the rpms will jump up. I am assuming this is related to the prop though 4 blades should get on plane easier.

Any advice on how to get a little better optimal rpm and acceleration performance. I am very inexperienced with dealing with prop dimensions.
"Either write something worth reading or do something worth writing" Benjamin Franklin

Replies

  • 803803 Posts: 175 Officer
    Any places around Broward county where I could find used stainless props or try out new ones before I spend all that money.
    "Either write something worth reading or do something worth writing" Benjamin Franklin
  • rehartlinerehartline Posts: 742 Officer
    If you call PowerTech and give them all of your boat and motor infomration they can size a good prop for you. They also have an exchange program. Tell them what perfromance you want, like is your hole shot more inportant than top end speed, etc. I got a 4 blade prop for my Yamaha and the performance was dead on what they said it would be.
  • BobberBobber Posts: 895 Officer
    Frank and Jimmies - best prop shop is SoFla.


    http://www.fjprop.com/
  • rehartlinerehartline Posts: 742 Officer
    Bobber wrote: »
    Frank and Jimmies - best prop shop is SoFla.


    http://www.fjprop.com/
    That's where PowerTech sent me to purchase my prop after PowerTech sized it. Agreed, good guys.
  • VeroDDVeroDD Posts: 311 Deckhand
    Sounds like you might need to raise the motor on the transom. Here's a good prop resource
    http://www.propmd.com/propeller-basics.html
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