How to prop a boat at altitude

[jacksonmj]

Looking at buying a boat this weekend and want to know what prop I should go with, I’m in Denver and roughly around 5,000 ft with the area lakes. The boat is a 94 BassCat Eyra with a 2016 Mercury Pro XS

[jarhead175]

Take it to the lake full of fuel and fill the livewell full of water. Keep notes of rpms during hole shot, WOT rpms, water pressure, and prop to pad measurement. Post that on the setup page. I wouldn't make any changes till you know what you got unless you just got lots of money.

[jacksonmj]

Jarhead thanks for the advise! I’ll be sure to run it and see what it does and go from there. It’s got a high 5 prop now and don’t think that’s what I want to run

[FES313]

Is the boat local? if it is, it may already be propped right. I have a couple of lakes that are above 3000 feet and my motor seems a little sluggish on those lakes. I run mine from sea level to 3300' with the same prop and if I went any higher I might consider a prop that is 1 pitch lower.

[martyd]

I run a 21 pitch on a 496 charger with a 255 yamaha 4 stroke up at spinny and 11 mile. 23 pitch at pueblo Boyd and horsetooth. Change to a 25 when I go back to Missouri.. Runs good at all places..

[fishnfireman]

Try posting this on the Bass Cat page and maybe someone with your general setup can get you going. They will need to know which XS motor you have... As you know getting on plane is the big problem at elevation and for sure that 5 blade can do that.
I've heard the BC / 2 stroke XS work well with the Fury props. Might have to go as low as a 21 depending on which mtr and the load you carry...
I fish Navajo (6000ft) on occasion and keep a prop that is 6 pitch lower than what I run at 1200ft.

[21XDC]

Merc don’t offer a 21p Fury.

[Finlander]

I would say a 25 Tempest plus at sea level and would bet is the prop already on it. I would guess 23 but Jarhead called it. Get the actual numbers for what you have first.

[Boondock]

Horsepower helps
pro xs could be 150-250
What prop is currently on it?

[OldTimer57]

The ONLY thing that matters is how fast can you spin the prop. Most motors have an RPM range (say 5000-5750). You want to prop it so that it won't exceed that upper bound during the year. This usually means propping it to 5750 in the coldest air you plan on running in. If, in the summer it drops below the lower limit for the RPM, you need to reduce pitch to get it back up into the power band. What others are using doesn't matter, it is your exact circumstances that will dictate the proper prop type and pitch...