Alumacraft competitor 175 tiller 70hp yamaha

[anzomcik]

This is for a friend of mine. He is looking to get a SS prop, possibly a jack plate he wants best performance that he can get.

Alumacraft competitor 175 tiller 70hp yamaha 2.33 gear ratio
GPS speed two guys light gear 34.5
6400 rpm WOT (6300 recommend)
13.375 dia prop 14 pitch AL

I did the test run, had two tachs both read the same, trimmed it to the max to get those numbers. prop held good. Normal running with out trimming to the max was 6200rpm and 32ish mph.

I mean those numbers are great as is, but he would like to pick a SS prop. It should be cut and dry, I am concerned there is little to improve based on what i got in testing so figure i would throw it out there.

 

[steelespike]

If you look up the Yamaha performance reports I think you will see he is just about there on performance.
SS props are not a cure all for performance. If I was going to try to squeeze out a little more I would
check out the Turning point Hustler. In the same pitch.About 1/2 the cost of ss with about the same performance.

 

[anzomcik]

I check all those out prior to posting my original post, you are correct he is right there. He would like to get more, it might not be feasable

 

[Sea Rider]

Yam engines wot rpm are usually in the 5000-6000 range, check factory info as you might already be over revving high with 2 up at 6400 stated wot rpm, much worst if one gets off the boat...

Happy Boating

 

[anzomcik]

I checked his manual at the ramp, it said 6300rpm.

I just checked it again downloading the manual from yamaha, F70 WOT 5300-6300rpm

 

[Sea Rider]

If already at top wot rpm there, there's nothing to maximize, just go for one pitch less SS prop to be there if wanting going for a SS prop. Check with driver solo his wot rpm to see how much rpm difference between 1 and 2 up.

Happy Boating