Prop Selection

[BrentAshurst]

i just bought a 97 maxum 2300sr it has a 5.7 motor(not the mag just the regular 350) alpha 1 out drive. i went to the river and it topped out at 30 mph at 4000 rpms. i checked the prop it has a 15 on it and the guy i bought it from had a spare that was a 16. both are 3 blades, my question is with the boat loaded up full tank and 10-13 people could i still get the boat to plane out if i went to a 4 blade 19 or 20? i waisted alot of fuel running that high of rpm but it is a big boat and i dont want to have it lugging around. what do most people run(propeller wise) on a boat this size and whats the rpm and speed?

[BrentAshurst]

sorry i am new and didnt know there was already about 100 post on this same issue. having said that i still need advice i put the 16 on and plan on going back to the river this weekend

[rens914]

yep
there's a lot to read on this question
thing is that the best you can do is read and try
that's what i did
i have a 4.3 v6 on a 23scr
switched from 3 to 4 blade
the 4 blade brings you faster i plane but needs more power
so eventually the rpm and top end speed sufferd
perhaps youre set-up (5.7) is stronger but sometimes it is what it is
i found out that the original prop was the best one
and
these boats run best with only 2 people, not to much fuel/water and limited gear on board
rens

[ss3964spd]

Brent,

That boat with that engine and drive, correctly proped, should probably top out around 45 MPH-ish with 2-4 aboard, a half tank of gas, and smooth water.

Find out what prop was factory installed and then go from there.

13 people on a 2300? Man, that's a lot of bodies. Please be sure you're not over-loading it - there should be a decal listing max persons and weight. Obviously, with that much weight on board, performance is going to be hurt and handling as well.

[Jerryh3]

http://www.maxumownersclub.com/forum...re-you-running

[shrew]

Originally Posted by BrentAshurst

i just bought a 97 maxum 2300sr it has a 5.7 motor(not the mag just the regular 350) alpha 1 out drive. i went to the river and it topped out at 30 mph at 4000 rpms. i checked the prop it has a 15 on it and the guy i bought it from had a spare that was a 16. both are 3 blades, my question is with the boat loaded up full tank and 10-13 people could i still get the boat to plane out if i went to a 4 blade 19 or 20? i waisted alot of fuel running that high of rpm but it is a big boat and i dont want to have it lugging around. what do most people run(propeller wise) on a boat this size and whats the rpm and speed?

Where you running 30mph @ 4000 rpms with 10-13 people on board, or is this more of a theoretical question? How many people and approx. how much gear, fuel and water were on board when you were running those numbers? A Merc 5.7 (either carb or EFI) should have a max. RPM range of 4400-4800 RPM's.

going up in pitch is going to give you slower hole shots and be slower to get up on plane. It should allow you to run at higher speeds, or at slightly lower RPM's for the same speed as a lower pitch prop. There is, however a law of diminishing returns which applies here. You Don't want a situation where the prop pitch is so high that you run UNDER the Max/ RPM range at Wide open Throttle (WOT). If you were reaching 3800-4000 RPM's at WOT, then you'd really be overpropped and straining the engine. If Max RPM's at WOT are over 4800, you'd be underpropped and over-revving the engine. Either are not healthy for the motor.

These numbers are all relative to thea amount of weight that is on the boat. Think of trying to pull the boat and trailer with a Honda Civic, vs a Ford 350. I would first start with 1/2 fuel, 1/2 Water, minimal gear and 2 people and get the boat up on plane. The get it to WOT and see where the RPM's are running. proper drive trim and tabs will help. Keep in mind current, water conditions will also slightly impact the numbers. See where you are from there.

In my opinion 10-13 is too many for that boat. It would be too many for my 2800. I wouldn't expect the 2800 to get up on plane with that many people on board.

[BrentAshurst]

sorry were down to 8 people and 2 small children full of fuel cause were going on a long river trip. 16 prop on it now but i am taking the tools to change back to a 15 if need be

[seapuppy]

Wow...that many people onboard the boat with kids???..I doubt if you will hit WOT with that kind of load....


try WOT without all the baggage and with a half tank of fuel.....you should hit recommended WOT then...or pert near that....then adjust the prop pitch....might wanna invest in trim tabs if your going to carry that kind of load consistantly...

also ensure you have everyone wearing pfd's especially the little curtain crawlers!!!...(kids)...

SP

[BrentAshurst]

ok put the 16 prop on full of fuel 9 adults 2 children 2 med ice chests wot was 3800 at 31 mph plained fine we even wakeboarded no problem pulled out of the hole fine, i am confident with 2 people it might hit 40. what should my wot rpm be on a 5.7 i ve read 4000-4500?

[Jerryh3]

I think it should be 4400-4800.

[shrew]

Originally Posted by BrentAshurst

ok put the 16 prop on full of fuel 9 adults 2 children 2 med ice chests wot was 3800 at 31 mph plained fine we even wakeboarded no problem pulled out of the hole fine, i am confident with 2 people it might hit 40. what should my wot rpm be on a 5.7 i ve read 4000-4500?

Your problem isn't the boat, motor, or prop. Just because the boat has a lot of seats, doesn't mean that we should run around with that many people on board. It just means people have options. 9 adults, 2 kids, two full coolers pulling a wakeboarder on a 2300 is (please take not offense) unreasonable. You are grossly overloading your boat.