prop problems, help

[harleymike]

Hello
I hope you can help. I have a 97 starcraft superfisherman,with 70hp force motor.
Problem is this. With 4 adults in the boat it will not come up on plane. It just plows water.
If I put one person on the bow , it comes up on plane. Is this normal, or is there something I can do to
improve this.
I have a 14pitch prop. I purchased an 11 pitch prop, but have not had the opportunity too try with 4 adults. I have noticed with just two adults and 3 children, both props work fine, but the 11 pitch seems too rev too high, and not as much top speed.
I also put dolphins on the motor.
One thing I noticed about the two props, The 11 pitch ;and 14 pitch both the same size , but the 14 pitch has differant shaped blades. The 11 pitch has skinner blades, the 14 are more like big elephant ears ( more surface area) is this maybe a problem.

Any suggestions would be great.
I prefer the 14 pitch, but is it a design issue with 4 adults in the boat.

thanks mike

 

[rndn]

Re: prop problems, help

Once on plane, what are your rpm's at wide open throttle(WOT)?

 

[mickjetblue]

Re: prop problems, help

I'm no expert on props, but I just went through a similar experience.

I wanted to find out what more pitch would do, and found that with a light load,
more pitch worked great! However, when I put a couple people in the boat with me,
I lost overall power and top speed. I had crossed over the efficiency threshold of pitch.

I went back to the mid range of pitch, and can boat fine with it, and don't have to change
the prop depending on who all is going out in the boat. When time and convenience
permits, I suppose changing the prop for conditions and load will work. Again, it's all a
balancing of circumstances. Oh, and pitch.

Good luck!

 

[rndn]

Re: prop problems, help

It's bad for the motor to prop for anything other than rpm's at wide open throttle. Once you get the correct size prop for your boat then you can do all kinds of things to help with the ride and hole shot. To help with hole shot you could go with a 4 blade prop or get the Nauticus Smart Tabs that sell for around $200 bucks.