Cajun Espirit Fish/Ski 1950 .........prop advice???????

[globug]

I need some advice from other Cajun owners here..

The boat currently has a 19 pitch, 3 blade aluminum prop..

I'm still breaking in a new powerhead, but some short bursts to near WOT, only got me to about 50 mph on the gps..

I haven't pushed it all the way to WOT yet....maybe next outing...

I have received conflicting info on what size/pitch prop I need..

The dealer says I need a 20-21 pitch Renegade or Raker..

Friends (boating enthusiasts) say I need a 23 pitch prop..

I don't want to spend $400 on a prop and it not be what I need..

I'd like to get the right prop the first time..

What I use the boat for is dragging the kids around on the tube, myself on the kneeboard, general cruising and fishing..

I don't need a "MONSTER HOLESHOT" or anything extreme, just a good "all around" prop that will let me open it up to 60 mph or so for fun runs across the lake...

Prop advice??

Recommendations?

[Chad7n7]

You may want to try posting this in the SETUPS BY TODD or PROPS board, bunch of knowledgeable guys on there should get you fixed right up!!

[houtex]

Glo -

I have the same boat, 1993 model, except for motor. Mine has 175 Faststrike Johnson. See photos in the Boat Pics topic posting, it's the last boat on page 2 of that topic posting.

Can't recall prop spec off top of my head. Will look it up and post ASAP. I do know it is 3 blade SS. I do beleive it is a 19 pitch. More on that later.

I had poor hole shot when pulling tube etc. Plus couldn't maintain speed or plane at slow speed, especially in turns. Way hard to control when pulling.

Speed was high 50's MPH at max RPM. Seemed fine although I always thought it ought to go faster. But I am not a speed demon and high 50's was fine. But because of pulling problem I looked into prop issue. Had same concern about investing in a prop only to find out it had no effect, or wrong effect. But my issue was a bit different than yours. I wanted better control at slow speed rather than faster speed.

So I installed one of those Hydrofoil jobs on the lower unit. Real bass boat junkies will laugh at them but it did what I wanted for $100 +/-. With it the boat jumps right up and I can pull tube, etc with control at slower speed and in turns. The top speed barely budged, now about 57 at top RPM.

This info relates partially to what you are after. Let me know what you do and how you end up. I am very interested in knowing, especially if you change props and get better speed. I'd like to know what does the trick. If you want to discuss let me know.

Houtex

[DJ from MN]

Can't be a 19p prop. In order to push a boat 67 mph with a 19p prop you would have to spin it 7000 rpm at .01% slip.

I gotta believe you are running at least a 23p on a 175.
EngineRPM ------ 6250 (750 rpm overspeed. SB 5500 rpm)
GearRatio ------ 1.86
PropellerPitch ------ 23
PropellerSlip ------ .10 (that's a very good hook-up)
SpeedMPH ------ 65.9

Not trying to be a smart axx here, the #'s just hit a blinking light when I read your post.

You are going to have to turn a 24p prop @5500 rpm with .10% slip to hit 60 mph. Without a jackplate and some fine tuning i'm not sure your 150 will turn that big of a wheel to those RPM's. Mine won't. I turn a reworked 19p(added progression and cup to make it run same as a 20p) and the most I have seen on the GPS is 47.9 mph.

Here is a link to a prop calculator to play around with:
http://www.rbbi.com/folders/prop/propcalc.htm

[FTLMech]

DJ I agree numbers don't lie. That is a good formula to figure top speed and speedo's will lie . I have a 23" 4 blade shooter on my 150 'Rude and can't go more if I wanted to. Hole shot is slow with 2 men in the boat 15-20 gal fuel. Wouldnt dare try to pull a skier or tube with this prop. Would like to try 3 blade with same or higher pitch, but cheeper to keep what I have. If any one is running this setup on 18' Cajun would like to hear from you.

[houtex]

DJ - If you are referring to my post, re-read it. I thought maybe I made a typo but it reads correctly. 57 not 67 .

With that in mind I be interested in how the math sorts out using your calculations. That is 57 by GPS, with RPM's maxing out at around 5600.

Thanks.

[DJ from MN]

OOOps, my bad....

Here are the #'s:


RM----------5600
Gear ratio---1.86
Pitch---------19
Speed--------57
Slip---You have selected a speed that is faster than the prop can go under these conditions with 0 slip.

You have to have a bigger wheel, or the prop has more progression and cup than a standard 19p.