Low RPM's on 18' G3 Pontoon 60HP Yamaha

hbulle13

Cadet
Joined
Jul 12, 2009
Messages
7
Hello,

I have a new 2009 18' G3 Pontoon boat with a F60 Yamaha 4 stroke.
Usual load = 3-4 people, 20Gal gas, 100lb's gear

From the dealer it came with a 10 5/8 x 12 Prop (3 blade alum.).
On dead calm water, it ran about 19MPH(spd gauge) at 4200 RPM WOT

The dealer checked and my throttle is correctly set.

I replaced the prop with a Turning Point Hustler 12 1/2 x 8 (3 blade alum.) and my numbers came out to 20MPH at 5000 RPM's WOT ( in reverse it is VERRY slow now. my trolling motor is faster.)

The dealer said that the motor is supposed to run between 5-6000 RPM, and the ideal point in my setup is about 5700 RPM.

Of course I would like to have as fast speed as possible , but my main concern is getting it to the correct RPM's before I get too many hours on the engine.


Any suggestions as what prop to try next, or anything else I may have missed.
 

hwsiii

Commander
Joined
Jan 25, 2009
Messages
2,639
Re: Low RPM's on 18' G3 Pontoon 60HP Yamaha

Bulle, welcome to Iboats prop forum and we will try to help you as much as we can but without more information no one can help you and I will tell you I need more information than anyone else. But if you would like my help fill this form out and I will help you as much as I can.

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
If you don?t know the ratio, you need to pull the plugs out and put a piece of tape across the prop and the lower unit and then cut it between the prop and the housing and turn the motor until the tape lines up with each other, it is easier if two people do this, so one can watch the prop while the other counts the revolutions of the motor
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
 

hbulle13

Cadet
Joined
Jul 12, 2009
Messages
7
Re: Low RPM's on 18' G3 Pontoon 60HP Yamaha

Iboats Boat and Motor Info
1. Year, make and model of boat 2009 G3 Pontoon
2. Length, width and base weight of boat, look for boat decal on back of boat 18' x 8' Dry Hull Weight 1340lbs, package weight 2370lbs2a.What is the recommended HP for your boat Max 75HP
3. Number of people and gallons of gas normally on boat 4 People, 20 Gal
4. What do you use the boat for Fishing, Tubing
5. Is it a Deep Vee and if so how many degrees of deadrise NO
6. Year, make and model of motor 2009 Yamaha F60LTR 60HP
7. HP and gear ratio of motor IMPORTANT 60 HP 13:24
If you don?t know the ratio, you need to pull the plugs out and put a piece of tape across the prop and the lower unit and then cut it between the prop and the housing and turn the motor until the tape lines up with each other, it is easier if two people do this, so one can watch the prop while the other counts the revolutions of the motor
8. Manufacturer?s recommended Wide Open Throttle (WOT) range 5000-6000
9. Anti-ventilation Plate height above keel of boat if it is an outboard in inches ? how do I figure on a pontoon?
10. Is it a bass boat or does it have a pad bottom NO
11. Does it have a hydrafoil, dolefin or trim tabs NO
12. Make, model, diameter, pitch and whether SS or aluminum prop Aluminum turning Point Hustler 12.5" x 813. 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 4700 RPM 19MPH on board gauges14. Are you at sea level or a higher elevation, give us the elevation in feet 3000ft
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 New engine, dealer says throttle is correct
16. How long has this prop been on the boat and why, at this time, do you think it is the wrong prop 2 weeks, still not getting correct RPM. Original Prop was 10 5/8" x 12 aluminum (4100 RPM 18 MPH)17. Does the prop show any damage that you can see NO
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
Want the RPMS around 5600
 

hwsiii

Commander
Joined
Jan 25, 2009
Messages
2,639
Re: Low RPM's on 18' G3 Pontoon 60HP Yamaha

Is this the high thrust motor from Yamaha.


H
 

hbulle13

Cadet
Joined
Jul 12, 2009
Messages
7
Re: Low RPM's on 18' G3 Pontoon 60HP Yamaha

No,

It is the standard mid range 4 stroke.

Brian
 

hwsiii

Commander
Joined
Jan 25, 2009
Messages
2,639
Re: Low RPM's on 18' G3 Pontoon 60HP Yamaha

Brian, will you be running the boat at this altitude all the time and how many people were on the boat when you got these speeds.


H
 

hbulle13

Cadet
Joined
Jul 12, 2009
Messages
7
Re: Low RPM's on 18' G3 Pontoon 60HP Yamaha

The three lakes I usually go to are 3400, 3652 and 4200 ft.
A little higher than I thought.

The numbers I gave were at the 4200ft elevation.
I was the only one on the boat with those numbers.

With 5 people the same day it ran 4400rpm and about 14-15 mph.

I will usually have 3-4 people on board.

Thanks,

Brian
 

hwsiii

Commander
Joined
Jan 25, 2009
Messages
2,639
Re: Low RPM's on 18' G3 Pontoon 60HP Yamaha

Brian I have not forgotten you, I am just pondering.


H
 
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