Help me pick a prop...

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curlybill

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Mar 21, 2010
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Johnson 90 spl motor, 15 1/2 foot Stratos 890 lb dry, current prop is a 3 blade 14x19, the boat almost stands straight up taking off, can't cruise at low speed (it won't plane out), at wide open I'm only hitting around 4600 rpm, any advise is greatly appreciated....
 
fireman57

fireman57

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Aug 24, 2004
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Re: Help me pick a prop...

Your not far off if you are hitting 4600. I believe, and there are great prop guys here that can tell you better than I, that you should hit around5-5200. If you lower your pitch a little that will get you closer. The not planing at slow speeds is a problem you will have with all boats because of the weigth distribution. You should be able to use your trim to solve this problem. If you post this in the prop forum you will get better response. Of course the mods might beat you to it.
 
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curlybill

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15
Help me choose a prop!!!

Help me choose a prop!!!

Posted this in the wrong forum so here we go, Johnson 90 spl motor, 15 1/2 foot Stratos 890 lb dry, current prop is a 3 blade 14x19, the boat almost stands straight up taking off, can't cruise at low speed (it won't plane out), at wide open I'm only hitting around 4600 rpm, any advise is greatly appreciated....
 
Bob_VT

Bob_VT

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Re: Help me choose a prop!!!

Re: Help me choose a prop!!!

merged
 
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curlybill

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Re: Help me pick a prop...

Thanks for getting this in the right place, any suggestions on a prop???
 
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steelespike

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Apr 26, 2002
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Re: Help me choose a prop!!!

Re: Help me choose a prop!!!

I would suspect some underlying problem.Is the motor in excellent tune,does the throttle open all the way.Prop excellent?Do you trim in for hole shot?
Is it possible the foam under the floor may have absorbed water?This can add a couple of hundred pounds right at the stern slowing hole shot and making it deifficult to styay on plane.Are tanks,batteries etc concentrated at the stern?
If these things check out you might try a 17" 4 blade prop.
This should help your hole shot and help stay on plane better.
 
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curlybill

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Mar 21, 2010
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Re: Help me choose a prop!!!

Re: Help me choose a prop!!!

steelespike said:
I would suspect some underlying problem.Is the motor in excellent tune,does the throttle open all the way.Prop excellent?Do you trim in for hole shot?
Is it possible the foam under the floor may have absorbed water?This can add a couple of hundred pounds right at the stern slowing hole shot and making it deifficult to styay on plane.Are tanks,batteries etc concentrated at the stern?
If these things check out you might try a 17" 4 blade prop.
This should help your hole shot and help stay on plane better.
Click to expand...

Motor is freshly tuned, at WOT the throttle is all the way open, Prop is in good shape and I trim all the way down out of the hole but it just raises up alot higher in the front than any other boat I have owned. As far as foam under the floor I don't know, there are no cracks in the hull or boat, I only had 3 gallons of gas and two batteries in it when I ran it....
 
Bondo

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Re: Help me choose a prop!!!

Re: Help me choose a prop!!!

Ayuh,.. So try the next pitch Lower,+ see how it works..
 
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steelespike

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Re: Help me choose a prop!!!

Re: Help me choose a prop!!!

curlybill said:
Motor is freshly tuned, at WOT the throttle is all the way open, Prop is in good shape and I trim all the way down out of the hole but it just raises up alot higher in the front than any other boat I have owned. As far as foam under the floor I don't know, there are no cracks in the hull or boat, I only had 3 gallons of gas and two batteries in it when I ran it....
Click to expand...

Looks like a 17" 4 blade may be the solution.
 
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bruce40

Seaman Apprentice
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Dec 5, 2009
Messages
46
Re: Help me pick a prop...

CurlyBill,
I would try a BRP Rogue 13x17. Thats a 4 blade that helps lift stern heavy boats. Should get your rpms up too.
 
hwsiii

hwsiii

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Jan 25, 2009
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2,639
Re: Help me pick a prop...

Bill, you have gotten some very good advice here from a lot of people. But unless you are running a stainless steel prop or an aluminum Turning Point prop I question why you are having the results you are with this boat.

Johnson 90 spl motor, 15 1/2 foot Stratos 890 lb dry, current prop is a 3 blade 14x19, the boat almost stands straight up taking off, can't cruise at low speed (it won't plane out), at wide open I'm only hitting around 4600 rpm, any advise is greatly appreciated.
Click to expand...

That is a very light boat with a lot of horsepower to be having it react the way it does, possibly it is the motor is just very heavy for such a light boat. But I would like to ask a few questions because I would like to explore a little deeper into this problem.

I would like to know the year and model numbers of the boat and motor as well as the material the prop is made of as well as the manufacturer and model of the prop. And a few pictures of the boat with at least one full view and another at the stern with the motor up so I an see what the hull form is and one with the anti ventilation plate parallel with the keel so I can see how high the plate is above the bottom of the boat. I would also like to know the speed you are attaining at 4,600 RPM, and whether it is by speedometer or GPS.

You might try reading this for a better understanding of changing props for better performance, and for the major differences between aluminum props and stainless steel.

http://forums.iboats.com/showthread.php?t=369057



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