Clonflicting information on how to pick prop.

lrdchaos

Petty Officer 1st Class
Joined
Feb 11, 2008
Messages
265
I have read on this forum to pick a prop based on the normal load in a boat. Like if my boat is supposed to run 4600-5000 rpm, pick a prop that will do that with the normal load in the boat. I just talked to mercruiser and they recommend running the boat with 2 people and a half tank of fuel and pick a prop that runs in that 4600-5000 rpm range. But if I do that, and then load the boat up with 6 people, full fuel, and all gear.....Won't it be to much prop at that point? I mean a little weight makes a huge difference. The reason I ask is because I want holeshot and don't want to have a prop pitched to high.
 

CharlieB

Vice Admiral
Joined
Apr 10, 2007
Messages
5,617
Re: Clonflicting information on how to pick prop.

Merc's opinion is that the MAJORITY of boaters USUALLY only run their boats with two people on boat, thus they recommend sizing the prop for the AVERAGE boater.

You are correct in sizing your prop to YOUR average boating loads.

A number of boaters carry two (or three) different props, and change the prop to match load conditions for that weekend.
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,771
Re: Clonflicting information on how to pick prop.

Merc is correct in that "average" is two people plus stuff. You are also correct that when you have 6 people you will have decreased hole shot and speed. So only you can determine how often two people will be normal load and how often 6 people will be average load. You can't have it both ways. If you prop for two it will suffer on hole shot and top end. If you prop for six it will perform as well as that prop can with the given load. However when you have only two aboard, you'll need to watch the tach as it will likely over rev. Yes -- prop selection is a crap shoot so many folks have two. Light load pitch for cruising, and another with less pitch for towing water toys or cruising with a heavy load.
 

wca_tim

Lieutenant Commander
Joined
May 28, 2007
Messages
1,708
Re: Clonflicting information on how to pick prop.

Like said above. It's kind of a catch 22... and is about comprimise. IF you prop for wot with two on board and put it near the top of the recomended range, you'll probably be ok with more on board. if you prop for wot mid range with a full load, you'll likely overrev when running light if you're not careful.

I like having a 4-blade that's a couple inches in pitch lower than I can turn to redline - for general use, towing boarders and skiers, taking a load for a ride, etc... I just know if I'm by myself or just my daughter and I, that I have to watch running out at wide opne throttle.

Then for those days when I konw it's going to be just me or me and the kiddo, I've got another prop that will go the fastest on wot.

That's the best plan anyhow. However, I'm beginning to think I'm some sort of addict or something. I stopped counting at 10 stainless props the other day...
 

lrdchaos

Petty Officer 1st Class
Joined
Feb 11, 2008
Messages
265
Re: Clonflicting information on how to pick prop.

Thanks for the help guys that's what I was hoping for...As I have a great 2 person prop and now with the high five 17 pitch, I have a great pulling prop for 5-6 people and a couple of skiers.
 
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