5200 RPM on a 4.3, any prop suggestions?

H20Rat

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Mar 8, 2009
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So just going through my new-to-me 2002 19' Hurricane deck boat, and she has a somewhat beat up Merc Vengeance 19". I'm also hitting 5200 rpm with it, so as long as I need a new prop, I might as well find something that fits a little better.
Anyway, any suggestions as far as model/pitch?



So the details:
1) Performance issue you are trying to correct.
Drop the RPM to 4800
2) Current prop manufacturer, model, aluminum or stainless as a minimum.
Merc SS Vengeance 19"
3) Current prop diameter and pitch (required).
14" diameter, 19" pitch
4) Wide open throttle RPM and speed with an average load (very helpful)
5200 RPM, 44 MPH on GPS (15% slip)
5) Engine/drive make, model, year, and HP
Merc 2002 2 barrel 4.3l Vortec on a Alpha 1.81
6) Boat make model, year, length and weight
2002 Hurricane Fundeck, 19', Dry weight is #3055, so max normal load is probably close to 3800#
 

89retta

Senior Chief Petty Officer
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Jul 18, 2010
Messages
772
I would try a Turning point 4 blade 19 pitch. That's what I run and gives me 4800 rpm and 47mph. The same prop in a 3 blade gives me 5300 and 45 mph
 

Sea Rider

Supreme Mariner
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Sep 20, 2008
Messages
12,345
If going by 2 + pitches rule of thumb to a 21 pitch, will surely drop more than wanted 4800 wot rpm. If it were my combo would try a 20 pitch prop, but possibly not available on that size ?

Happy Boating
 

H20Rat

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Mar 8, 2009
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5,199
In theory I should drop 400 rpm with 2 extra inches of pitch, so it should put me right at the sweet spot. (rated RPM range for the 4.3 is 44-4800) Kind of leaning towards a 3 blade Turning Point mach 3, much better price than the merc props if it doesn't work out.
 

SkiDad

Lieutenant Commander
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Jul 18, 2010
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1,518
turning point props are nice but you wouldn't want to drop down in pitch as there props run like the next size up - that has been my experience. YMMV
 

H20Rat

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Mar 8, 2009
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Tried a turning point 19p stainless, ended up at just a hair over 5000 rpm at 41 mph (17% slip, worse than the dinged merc vengeance prop). It also doesn't like watersports, especially tubing. Blows out pretty easily on turns.

Going to try a 21p turning point next.
 

jimmbo

Supreme Mariner
Joined
May 24, 2004
Messages
12,944
If you buy the TP brand of props, examine the prop very carefully for inconsistencies(blade contours, blade edges), before you hand over your money. QC seems to be lacking at the overseas plant. But they are the cheapest prop on the market.
 

H20Rat

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So that was the other problem on the 19p. It vibrates/rumbles and the outside rim of the hub has SUBSTANTIAL runout! (like 1/4 of an inch)
 

Tail_Gunner

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Jan 13, 2006
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6,237
A perspective... opinion.... First under ideal conditions a 3 blade may give you one maybe 1/3 mph higher top end speed at wot, bear in mind most boater's only spend 10% of there time there. Hmm inboards anyways... and some will jump out of there chairs at that statement, Now a 4 blade will run smoother, improve hole shot, improve midrange performance, and provide more lift. 99% of the time there are always exceptions, A 4 blade ss say Solas HR titan should pull down your rpm give you more performance up to say 42 mph lower your slip etc etc etc. Try not to get caught in absolute perfection or extremes, boating conditions vary all the time. Water temp air temp & humidity can change things up all the time. Solas is well known to be a performer and is not the end all prop design but very consistent very reliable along with being cost effective. Good luck and enjoy this summer.
 

Bob_VT

Moderator & Unofficial iBoats Historian
Staff member
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May 19, 2001
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26,019
I had my Hurricane 187IO 4.3 out today with a Solas 4 blade 14X21 which is a downsize from the 23 pitch 3 blade that was on it. I feel an improvement with a better low end and mid range and only lost 1 MPH I am turning 48 mph @ 4700 rpm. That is based on the dash speedo and not GPS. Hey it was a good price and it works ;)
 

H20Rat

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Mar 8, 2009
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So tried out the 21p Turning Point, much better! Although I couldn't do a true WOT run (rough water, bimini was up, windy, etc...), it did seem to drop the RPM down to around 4800 for the couple of seconds I was at WOT.

Bob_VT, I actually have a 4 blade aluminum Solas 21p hanging on the shelf, will probably try that next weekend. I ran a Solas 19p 4 blade on the previous boat and was happy with it.
 

H20Rat

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Mar 8, 2009
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Just updating the old thread. Tried my Solas 21p 4 blade aluminum that I had on the shelf and it fits this boat probably the best. Very well balanced compared to TP stainless steel props. I hit 43mph GPS at around 4800 or a little higher rpm, 18% slip. Full fuel load (40 gallons)

I'll keep the 21 TP around as a spare, it does seem to actually work better for skiing, it is vented and rpm jumps up fast. The 4 blade solas keeps rpm's lower and the 4.3 has to work a little harder to get things moving.


So... summary:
Turning point props are crap. Poor quality control, and poor performance. The hubs of both of the TP props wobble if you spin it by hand, the 21p isn't nearly as bad though. The Solas has zero wobble. And a Vortec 4.3 2 barrel is a substantially stronger motor than a non vortec 4 barrel. (my previous 4.3 couldn't swing the 4 blade 21p Solas)
 
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