5 Blade Mercury High 5 Prop

[Stingray185GXi]

I have a 2010 Stingray 185LX with the 150hp Volvo Penta 3.0GXi. I am currently running a Solas HR Titan 4 blade stainless steel prop with a 20" pitch. This prop provides good overall performance including a WOT of 4400 RPM at 45MPH GPS, excellent bite in the turns, and very good midrange acceleration. However the boat is used primarily as a ski boat and I am considering a new prop in order to provide better low in acceleration and hole shot so I can more easily pull slalom skiers up from deepwater starts. I am wondering if anyone has any experience with the Mercury high 5 or Quicksilver QST 5, particularly in smaller boats with 4 cylinder power. I am thinking about going with a 19" pitch in order to improve acceleration and also because I can safely increase my WOT by 400 RPM and still be within manufacture specs.

Thanks for your help

 

[alldodge]

I have a 2010 Stingray 185LX with the 150hp Volvo Penta 3.0GXi. I am currently running a Solas HR Titan 4 blade stainless steel prop with a 20" pitch. This prop provides good overall performance including a WOT of 4400 RPM at 45MPH GPS, excellent bite in the turns, and very good midrange acceleration. However the boat is used primarily as a ski boat and I am considering a new prop in order to provide better low in acceleration and hole shot so I can more easily pull slalom skiers up from deepwater starts. I am wondering if anyone has any experience with the Mercury high 5 or Quicksilver QST 5, particularly in smaller boats with 4 cylinder power. I am thinking about going with a 19" pitch in order to improve acceleration and also because I can safely increase my WOT by 400 RPM and still be within manufacture specs.

Thanks for your help

It should help but not that much IMO. Every blade added also adds drag, drop pitch should compensate for the added blade. I would lean more to keep the 4 blade and drop pitch to 19 or go 3 blade at 20, to get your WOT closer to the max at 4800.

 

[SkiDad]

I agree. Get the same prop you have in the lower pitch. The 18p of Hr Titan 4 should be perfect. You will loose about 2 mph but make a huge difference for skiers.

 

[steelespike]

Assuming the GPS is accurate It appears the tach may be way off. Using 1.97 or 2.18 ratio you can't make 45 at 4400.
Calculates to negative slip. If we guess 12% slip we get 5300 rpm.@ 45 mph.I wouldn't make any prop change till you verify the tach.
I also feel the high 5 is better suited to more hp.

 

[Stingray185GXi]

Thanks for all your replies, in response to steelespike I agree that there is something odd going on with regards to prop slip being negative. I thought the same thing last season and I am now confident that my tach is accurate and my speed has been verified using multiple GPS and is within 1MPH of the speedometer on the boat. The lower unit ratio is 1.97, I finally came to the conclusion that despite my current prop being labeled as a 20" pitch it behaves like it has more pitch do to its design and lots of cupping. I have read elsewhere of other people running the same prop that their prop also behaves like a higher pitch than it actually is. The main reason I was considering the high five prop was the exellent reviews I have read about it especially when it comes to improved acceleration which is what I am looking for. I also figured that since it's diameter is almost a full inch smaller than my current 4 blade that there shouldn't actually be much more drag even with the extra blade.

 

[Stingray185GXi]

I ended up testing a couple different props (both 4 and 5 blade) and decided to go with a 5 blade Quicksilver QST5 which is the same a a Mercury High Five in a 21 pitch. The boat performs MUCH better with this prop than the Solas 4 blade, I think the smaller diameter as well as design of the high five is a better fit to my boat. It jumps onto plane almost instantly with very little bow rise (smart tabs help here too) and accelerates very quickly to about 40MPH, top speed is now 47MPH GPS at 4950 RPM. I couldn't be happier with this prop and it has made deepwater slalom ski starts much easier especially when the boat is loaded or multiple skiers.

As a side note: My recommended WOT is 4800 RPM and the 21 pitch high five allows me to just tickle the rev limiter at 4950RPM with a light load, when I tested a 19 pitch high five i could hit the rev limiter while still accelerating.