2004 5.0 20ft Maxum

Listed the boat the prop is a 145 X 19. Only had the boat for a couple weeks, engine runs strong love the boat but..... I'm only getting 3900 RPMs. The prop is slightly dinged, I definitly run worse on my 19 ft Bayliner. Just curious, what things would be keeping me form getting close to my WOT RPM's of 4300 to 4800. It gets on a plan fairly quick, pulled 2 people tubing haven't pulled a skier yet. Doesn't seem to jump out quick enough for a skier. I can think of 3 things that would keep me from max. Boat bottem, prop or engine.

I was thnking of going to a 4 blade prop but that would lower my RPM's so I'm struggling with the prop being the problem. Help please.

Re: 2004 5.0 20ft Maxum

post some pics of the prop...and the boat.

Re: 2004 5.0 20ft Maxum

You appear to be defnitely over propped but we need more information.
Iboats Boat and Motor Info
1. Year, make and model of boat
2. Length, width and base weight of boat, look for boat decal on back of boat
2a.What is the recommended HP for your boat
3. Number of people and gallons of gas normally on boat
4. What do you use the boat for
5. Is it a Deep Vee and if so how many degrees of deadrise
6. Year, make and model of motor
7. HP and gear ratio of motor IMPORTANT
7A If you have a mercruiser and don?t know the ratio get your serial off the outdrive and go here http://www.sterndrives.com/mercruisersterndrives.html
8. Manufacturer?s recommended Wide Open Throttle (WOT) range
9. Anti-ventilation Plate height above keel of boat if it is an outboard in inches
10. Is it a bass boat or does it have a pad bottom
11. Does it have a hydrafoil, dolefin or trim tabs
12. Make, model, diameter, pitch and whether SS or aluminum prop
13. WOT RPM and speed from your current prop and how much gas and how many people were in the boat for the test data and is the speed by GPS. If you do not have a tach you can buy a Tiny Tach for $ 50
14. Are you at sea level or a higher elevation, give us the elevation in feet
15. Has your motor been tuned up lately and have you checked that the carburetor butterfly is opening all the way, checked compression, and looked at the plugs and checked spark, all of the forgoing could be the reason your prop is not attaining full RPM
16. How long has this prop been on the boat and why, at this time, do you think it is the wrong prop
17. Does the prop show any damage that you can see
18. What problems are you trying to cure or what are you looking for the boat to do that it is not doing the way you think it should or to your expectations

REMEMBER, The numbers I give you will be NO better than the information you give me

The only thing I ask of you is to come back and give me a report of WOT RPM and speed for my database.

H

Re: 2004 5.0 20ft Maxum

hwsiii said:

You appear to be defnitely over propped but we need more information.
Iboats Boat and Motor Info
1. Year, make and model of boat
2004 Maxum SR3
2. Length, width and base weight of boat, look for boat decal on back of boat
20ft 8ft beam 4,000 lbs
2a.What is the recommended HP for your boat
220
3. Number of people and gallons of gas normally on boat
2 people gas 30 gallons
4. What do you use the boat for
5. Is it a Deep Vee and if so how many degrees of deadrise
I would say medium vee
6. Year, make and model of motor
2004 MercCruiser 2 barrel
7. HP and gear ratio of motor IMPORTANT
7A If you have a mercruiser and don?t know the ratio get your serial off the outdrive and go here http://www.sterndrives.com/mercruisersterndrives.html
220 HP Gear 1.62:18. Manufacturer?s recommended Wide Open Throttle (WOT) range
4300 to 4800
9. Anti-ventilation Plate height above keel of boat if it is an outboard in inches
N/A
10. Is it a bass boat or does it have a pad bottom
N/A
11. Does it have a hydrafoil, dolefin or trim tabs
Just the standard trim on the outdrive
12. Make, model, diameter, pitch and whether SS or aluminum prop
Aluminum prop 145 X19
13. WOT RPM and speed from your current prop and how much gas and how many people were in the boat for the test data and is the speed by GPS. If you do not have a tach you can buy a Tiny Tach for $ 50
WOT 3800 RPM 38 MPH 35 gallons 3 people
14. Are you at sea level or a higher elevation, give us the elevation in feet
Sea Level
15. Has your motor been tuned up lately and have you checked that the carburetor butterfly is opening all the way, checked compression, and looked at the plugs and checked spark, all of the forgoing could be the reason your prop is not attaining full RPM
Tuned recently before I bought the boat
16. How long has this prop been on the boat and why, at this time, do you think it is the wrong prop
Probably stock prop, just curious about not being able to reach WOT
17. Does the prop show any damage that you can see
Paint worn, and a little bit of nicking and small bends at end of blades
18. What problems are you trying to cure or what are you looking for the boat to do that it is not doing the way you think it should or to your expectations
Just want to get the maxium performance out her.

REMEMBER, The numbers I give you will be NO better than the information you give me

The only thing I ask of you is to come back and give me a report of WOT RPM and speed for my database.

H

Click to expand...

Let me try this again.

Re: 2004 5.0 20ft Maxum

Powder when you have the ends of the blades on a prop there is no way to know what that is doing to the RPM. Can you borrow a prop from someone to try, so we can have a good baseline.
With the information you gave me I show you should have a 17" pitch prop instead of the 19" you have now. Theoretically this will only increase your RPM by about 460 RPM. That will only bring your RPM up to about 4,350 RPM, and I have to assume that you will gain more RPM with a prop that doesn't have any bent blade tips.
Here are my numbers.

Prop Picker




Prop Change





H

Re: 2004 5.0 20ft Maxum

Thank you sir, I apreciate the info you have given me as well as the effort you have put into this, a lot of hard work and thought, and I can tell you are a true boating afficiando. Thanks from me and all before and after. I will try to get a new prop this morning. Going out today will keep the old on. Want to get times for getting on a plane, first. Will try the new prop tomorrow and get the info back to you next week. Thanks again.

Re: 2004 5.0 20ft Maxum

That sounds very good and we will run some numbers when you have the new prop RPM and speeds.


H