www.iFourWinns.com

I experienced this problem last year while on our vacation in the mountains. Elevation there is about 4850, home for us is about 400'. I have a Merc 4.3 MPI and I experience some challenge getting up on plan when pulling the tube. I've swapped my 3 blade Aluminum prop for the 3 blade Stainless Steel and can't say I feel any better pull. I don't need the high speed as much I need more power taking off. Anyone care to point me in the right direction? Is this a prop issue or should I be thinking about tabs?

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2007 Four Winns 190 Horizon Merc 4.3 MPI

Our boat on Crescent Lake in Oregon

Is the stainless prop the same size/pitch as the aluminum? Tabs probably wouldn't hurt but I doubt they'll help that much with this problem.

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Mike
2005 Four Winns 230/240
VP 5.7GXi/DP
1998 F-150 XLT
Boat Pic

Thanks Mike, went and looked and based on the markings both are 21

SS-Apollo X45 993045 14-21
Alum-832832A45P21

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2007 Four Winns 190 Horizon Merc 4.3 MPI

Our boat on Crescent Lake in Oregon

I'm a flatlander and don't have to deal with this, but I'm thinking you might need one prop for home and a different one for the high altitude to compensate for the lower power the engine is able to generate there.

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Mike
2005 Four Winns 230/240
VP 5.7GXi/DP
1998 F-150 XLT
Boat Pic

Thanks Mike, I'm thinking I'll will need that too. For around here at 400' I'm great, just when we get in the mountains (where we like to vacation) I'll need something different.

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2007 Four Winns 190 Horizon Merc 4.3 MPI

Our boat on Crescent Lake in Oregon

The thinner air up in the mountains will cause your engine to run differently, and have allot less power. I am not 100% sure how the MPI models meter air, but I have a feeling that you are experiencing this same condition. If it's like the carb'ed engines, a timing adjustment should help you out some. This should be discussed in your engine service manual. You can often find copy's of them online. It will give you a different base timing mark's every 1000 foot increase in elevation IIRC. But reguardless, you will still never make the same power in the upper elevations, and therefor you would be much better off with a 19P prop or maybe even lower while up there. While navigating in unfamiliar waters I would highly recommend an aluminum prop. I personally use and recommend Solas.

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99 Horizon 190 - Volvo 5.7
06 Sea Doo RXP (79 GPS) / 05 Sea Doo GTX Limited (74 GPS)

Thanks Jordan, I've got the manuals so I'll do some digging. Thanks for the prop advice too. I always start of with the Aluminum too, swapped over after a couple days and making sure the high level didn't attract a bunch of debris in the lake.

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2007 Four Winns 190 Horizon Merc 4.3 MPI

Our boat on Crescent Lake in Oregon

I too would recommend a 19 pitch, but if you want excellent hole shot, go 17, but you will have to watch that with that prop the RPMs to not go over what the MFG has recommended.

We boat anywhere from 3600 to 7000 foot elevation. Mountain lakes are pretty, but elevation does its toll on power. Need an 8.1L LOL

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2000 248 5.7L DP
'92, '94 SXI 750, '08 STX 15F, '12 Ultra LX 300
Videos

Bigger would be nice but for the short time we've been at that elevation I couldn't sell it to my wife. I can sell the idea of a new prop though. I've got a call to a friend that I think has the same motor on a different boat to see if he has one I could try first.

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2007 Four Winns 190 Horizon Merc 4.3 MPI

Our boat on Crescent Lake in Oregon

Bigger motor comment was really intended for myself. 7000 lbs boat with a tiny 5.7L at 6500 ft elevation = very poor performance

If your friend has one to try, good deal. If not, some boat dealers and / part houses will demo props. I had done this with our last boat.
Current boat has duo props (F3), high alt gear ratio, and I still need more umph.. thats where the 8.1L comment came from.

Oh ya, if you are still thinking tabs, dont. Save your money for other toys or mods. When you upgrade boats, then consider tabs. I wish our 245 sundowner had them, but anything under a 22-24' boat I personally dont think they are necessary, but a nice option if they are already there.

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2000 248 5.7L DP
'92, '94 SXI 750, '08 STX 15F, '12 Ultra LX 300
Videos