www.iFourWinns.com
https://www.smwebhead.com/phpBB3/

Prop or tab advice
https://www.smwebhead.com/phpBB3/viewtopic.php?f=11&t=8179		 Page 1 of 1
Author:  Y-Guy [ Sun Aug 07, 2011 4:04 pm ]
Post subject:  Prop or tab advice
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?
Author:  230 Mike [ Sun Aug 07, 2011 4:18 pm ]
Post subject:  Re: Prop or tab advice
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.
Author:  Y-Guy [ Sun Aug 07, 2011 6:11 pm ]
Post subject:  Re: Prop or tab advice
Thanks Mike, went and looked and based on the markings both are 21

SS-Apollo X45 993045 14-21
Alum-832832A45P21
Author:  230 Mike [ Mon Aug 08, 2011 1:24 am ]
Post subject:  Re: Prop or tab advice
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.
Author:  Y-Guy [ Mon Aug 08, 2011 1:30 am ]
Post subject:  Re: Prop or tab advice
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.
Author:  JordanFTW [ Mon Aug 08, 2011 7:43 am ]
Post subject:  Re: Prop or tab advice
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.
Author:  Y-Guy [ Mon Aug 08, 2011 10:49 am ]
Post subject:  Re: Prop or tab advice
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.
Author:  powellcrazy [ Tue Aug 09, 2011 8:38 pm ]
Post subject:  Re: Prop or tab advice
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
Author:  Y-Guy [ Tue Aug 09, 2011 11:36 pm ]
Post subject:  Re: Prop or tab advice
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.
Author:  powellcrazy [ Wed Aug 10, 2011 8:21 pm ]
Post subject:  Re: Prop or tab advice
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.
Page 1 of 1 All times are UTC - 6 hours [ DST ]
Powered by phpBB® Forum Software © phpBB Group
http://www.phpbb.com/