Prop selection VP 5.0GL-B motor with a SX-M 1.60 ratio outdrive

[ddbyrd3]

So I took my boat out this past weekend, and she ran beautiful.. I am running a 14 1/4 x 20 - 4 blade stainless steel Stiletto prop. At full trim, semi glass water conditions I can only pull 4600RPM WOT. I believe I should be pulling 4800.

I am in the market for a new Stainless Steel 3 blade prop. I am curious as to your recommendations. I am thinking either a 14 3/4 x 19 or just replacing the stock size 14 1/4 x 21 with 3 blades.

I would like to pull that extra 200RPM.

 

[Maclin]

"I would like to pull that extra 200RPM."

Leave someone on shore

A 3 blade 21p would probably do it, at the expense of some holeshot.

 

[ddbyrd3]

That's the direction I was leaning.. Prop recommendations?? Solas, Stiletto, ect??

 

[steelespike]

Rpm doesn't mean much without the wot gps speed.
Usually going to a 3 from a 4 would add rpm. naturally no pitch change.
Probably add a little speed.Stick with the stiletto.

 

[Maclin]

Yeah Steele, had my PropMan cap on backwards. Conventional wisdom when going from 3 to 4 blade is drop one in pitch, so conversely as you said a 19p would be more in the center of the target.

 

[ddbyrd3]

I understand that... The factory prop was a 14 1/4 x 21 3 blade.. I installed a 14 1/4 x 20 4 blade. My thought was to go back to a 21 pitch 3 blade stainless.

 

[steelespike]

Before any changes we should see the wot speed with a 20" 4 blade.We need to know if the numbers add up.
Do you feel a 3 blade 21" delivered 4800 rpm?

 

[ddbyrd3]

I was running 50MPH full fuel load 2 people. I don't know if the 3 blade will give me the extra 200RPM. the last time I used a 3 blade was an aluminum prop and I know the SS prop out performed it. If I remember correctly I pulled 4600RPM at around 45MPH. The aluminum prop I was running was a low cost prop. You could feel that is wasn't getting a good bite in the water. It was a 14 1/4 x 21.

 

[steelespike]

4600 @ 45 w a 21" calculates at 20% slip. Your suspicions of poor "bite" seem real.

 

[ddbyrd3]

I think either the aluminum prop is a lower quality prop and I was getting excessive flex, or the hub is beginning to slip. That's why I am considering going to a 21 pitch SS 3 blade. I know 200RPM seems to "nit picky" But if the WOT max RPM is 4800 which I believe it is for my motor, than I want it.. Just not sure if I need a 19 verses 21 pitch..

 

[Senior B]

My last boat was a 20ft Bow Rider with your same engine and drive ratio set up. I had 2 aluminum 3 blade props. A 19P & 21P. I got 4800 RPM and 51MPH on GPS with the 19P and that was my ski prop of choice. I got about the same top end at 4500 RPM, but a better cruise speed for RPM with the 21 and that was my cruise/ long distance prop. I could still ski with it, but it was noticeably different hole shot if the boat was heavy with people and gear.

 

[ddbyrd3]

What prop brands were you running do you remember??

 

[vkjazz]

I also have the same setup 5.0 Volvo SX-M 1.60. I have run assortments of 19, 20, 21 pitch all 3 blade. On my hull which is the 2005 Four Winns 190 I am able to get to 4800 and smidgeon over 51 mph with the 3 blade Solas 20 pitch. Very pleased with it for all around use, wakeboard, kneeboard, tube and cruising. The 19 pitch I have run did better with heavy loads.
Hope this was some help.
Best of luck!

 

[jimmbo]

Deep six the 4 blade. I personally like Mercury's Enertia Prop. It has an incredible bite on the water, on your unit a 21 or 22 should put you in the ballpark. BRP Raker is pretty good too. Next in line would be a Stiletto, it's a decent prop

 

[ddbyrd3]

Jimmbo, you recommend a 3 blade I take it??

 

[jimmbo]

I've really like the Enertia, and yes it is a 3 blade prop. I wish they still made 2 blade props for non-race usage, but...

 

[ddbyrd3]

Resurrecting my old post.

So I ran my boat all last season with my 4 blade SS Stiletto. And switched to my low budget 3 blade AL. I am unable to pull WOT RPM with either.
So I just found a brand new Volvo Penta 14 3/4" x 19 SS prop. I will run this prop and see how she does. I have high hopes, it is a beautiful prop....

 

[89retta]

I was running that same Volvo SS prop on my boat. 4.3 GXI 225hp and I was hitting the rev limiter very easy with it. Post how it works for you.

 

[ddbyrd3]

Will do, plan to take her out on the 27th

 

[QBhoy]

Rpm doesn't mean much without the wot gps speed.
Usually going to a 3 from a 4 would add rpm. naturally no pitch change.
Probably add a little speed.Stick with the stiletto.

Not sure that’s the case always. Most 4 blades have a bigger diameter and as far as I was aware...like for like pitch swap from 3 to 4 would drop the revs, better hole shot, but lose top end ?