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Which Propellor for Classic 17Ft Montuak-Super Sport
I am new to the forum (great place) I am not new to boating. I have SuperSport Limited, same hull as a Classic 17 Ft Montauk.
I wondering what seems to be the best all around prop for this hull. I run a 2 stroke 90 HP Yamaha. With a 17inch SS K series prop it will jump to 5700 RPMs with a moderate to light load (2 adults full tank). I tried a 19 inch Michigan Ballistic last season, did not get my desired results. Top end with only myself was 4900 rpms; loaded it dropped to 4500 RPMs. Since it jumps to 5700 With the 17 I feel I have a little room to play and still stay at the upper end of the RPMs, desired (5300-5400) for water sports
I tried a 19 Yamaha K series yesterday, got only marginally better results compared to the ballistic. 5100 trimmed out with a light load (1600 lbs total) although 5100 is only 200 RPMs less than my desired results, it really struggled to get there. Also seems that a drop of 600RPM is excessive for the identical prop in the next size.
What have you found to be the best all around prop?
It is telling that you achieved 5700 RPM with the 17" and only 5100 with the 19". That is a drop of 600 RPM for only two inches of pitch change which is about twice what we expect to see.
What changed between the two days you tested those two props? Was it warmer the day you tested the 19"? Were you more heavily loaded that day? Something is amiss.
Frankly, based on the data you've presented, the 17" sounds about right.
When you say "K Series", I presume you mean either the OE Yamaha aluminum prop or the so-called "Black Steel" prop, both of which use the same design and are painted black. Which one? They will not perform the same. "K Series" just means it is a Yamaha prop that will fit the intermediate size gearcase.
The other prop to try would be the Stiletto Advantage I in the 13-1/4" x 17" size. This should be a wee bit faster than the 17" Black Steel prop.
Exactly my point, 600 RPM is a big drop for 2 inches in pitch, could even be more. It was a struggle to to get to 5100. Easier to get to 5700 with 17. Conditions , temp, and humidity about the same. Both props are K series black stainless. Surprising difference. What is really telling is that the 17 also has a few very slight dings on the edges and it still got to 5700...
The 19 is brand new. The 17 has a a lot of balls to it. With the 19, seems a bit weak, have not tried a heavy load yet. I will try wake boarding with my teenage son tomorrow and see how it does with a load.
With the ballistic, polished stainless, 13 3/8 X 19, I only saw 4900 MAX. The is K is 13 exactly on Diameter, a 1/4 inch may make a sight difference. I may modify the 17 and add extra cupping or change pitch to 18.
