Need a new prop

[virii01]

Sorry if some of this is a repeat of my "need help identifying my prop" thread. I got it ID'd so I thought I'd start a new thread about the replacement.

Boat is a 1981 Mark Twain V-Sonic 170. 17ft, V hull, heavy for its size from what I've read.
Motor is a 1982 Johnson 115, 2:1 gear ratio.
Prop is/was a Michigan Wheel model 011001. 3 blade 14" diameter, 13 pitch.
http://boatpropellers.iboats.com/Jo...101654&**********=128882041&*******=996617342

I want to replace the prop because it is damaged, likely beyond repair.

At WOT, the tach shows just under 6,000 RPM, the speedo shows just under 35mph. I didn't have my GPS handy to verify the speed. From what I've read those RPMs are a little high for the motor. (should be <=5500)

The vent plate on the motor sits just below the hull, maybe 1/2 to 3/4 inches lower. I don't have any pics available at the time. The motor is mounted on the lowest setting.

Questions:
1. Should I change the size and/or pitch?
2. Any recommendations on a replacement brand/model?

Thanks

 

[virii01]

Re: Need a new prop

Did I ask a dumb question or not provide enough details?

 

[hwsiii]

Re: Need a new prop

Virii, are the numbers you gave us with the prop in the damaged condition, or are they before it was damaged.



H

 

[virii01]

Re: Need a new prop

Virii, are the numbers you gave us with the prop in the damaged condition, or are they before it was damaged.



H

That was with the damaged prop. The operation seemed smooth at WOT but a little rough at low-mid RPM. I wasn't sure if that was due to prop condition or just the inherent behavior of the V4 Johnson.

The prop itself has a small nick out of one blade, one blade in fairly good condition, and the third blade with a sizable chunk missing out of the third blade. The third blade has the last 1/8 inch or so missing off of the tip. I can provide a pic if necessary but it will be a few days as I am away on business.

 

[hwsiii]

Re: Need a new prop

Virii, when you come back if you will take the boat out and get us a GPS speed and true RPM we will get you propped right. Right now with the numbers you gave me I am showing a prop slip of only 2% and I don't believe that number, as those are heavy boats and stern heavy as well and that is just too good in my opinion.

I also believe if we can raise the motor up a couple of notches we will gain some speed and RPM as well.

You might try reading this for a better understanding of motor height, changing props for better performance, and for the major differences between aluminum props and stainless steel.

http://forums.iboats.com/showthread.php?t=369057

And for your particular motor it would be best to have the RPM about where they are right now.

H

 

[180shabah]

Re: Need a new prop

Sounds like were headed in the right direction - I agree motor should probably be raised.

 

[virii01]

Re: Need a new prop

Virii, when you come back if you will take the boat out and get us a GPS speed and true RPM we will get you propped right. Right now with the numbers you gave me I am showing a prop slip of only 2% and I don't believe that number, as those are heavy boats and stern heavy as well and that is just too good in my opinion.

I also believe if we can raise the motor up a couple of notches we will gain some speed and RPM as well.

You might try reading this for a better understanding of motor height, changing props for better performance, and for the major differences between aluminum props and stainless steel.

http://forums.iboats.com/showthread.php?t=369057

And for your particular motor it would be best to have the RPM about where they are right now.

H

Due to the condition of the prop, I don't really feel comfortable running it anymore. As such, I'm going to order a prop and go from there. Right now I'm liking the Turning Point Hustler. With everything I've provided, would I be best to stick with the 14/13, or move to something else? Is there any sort of exchange policy on props purchased here from iboats?

 

[180shabah]

Re: Need a new prop

I don't know iboats policy, but TP has a prop exchange program. As long as the prop your return is still in new condition, you pay shipping cost and they replace the prop for free.

 

[virii01]

Re: Need a new prop

I spoke to a tech from Turning Point (Phil?) and based on what I've outlined above, he recommended the Legacy model in 13 3/4 size and 15 pitch. He stated that this would lower my RPMs some to a better range for my motor plus give me a little more speed. Thoughts?