pitch range?

[scottbeef]

I do not have all the info needed so I am not looking for the perfect prop. Just a general range. We have a new to us bass boat and are working out the kinks. it is
1 1986 winner zz580
2 17.5' 950lbs
2a max hp 150
3-2 people and 24 gallons gas
4 used for recreational fishing/skiing
5 not deep v it is a bass boat
6 1977 Johnson140 hp

That is about all the info I have with me. Currently it has a 21 pitch ss prop. The boat has a hard time getting up on plane. one up on plane it does about 37. Should be high 40s to low 50s. YES the motor is mounted at the right height. It does throw up a heck of a rooster tail. It is almost like the motor powers right through the prop. If that makes any sense. I just want to see if we are anywhere near the typical pitch prop or if it should be more like a 25 or 15/17?
Thanks
Scott

Or maybe we are in the correct range already?

 

[hwsiii]

Re: pitch range?

Scott, i show that motor to have a 2:1 gear ratio and recommended WOT RPM to be 4,500 to 5,500 RPM, please verify this. If that is true and you are turning about 5,400 RPM at WOT with a 21" prop you are showing a prop slip of 31% and that is ridiculous for that boat. I have my opinion of your problem but I need more information first.

Prop Slip

If you would like more help please fill in the following form.

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

 

[scottbeef]

Re: pitch range?

Like I said it is a work in progress. We have not been able to get a tach to work on the motor yet. The motor does not sound like it is overrevving. The motor looks like it is mounted where most dealers would have set it up back in the 80s. Mounted as low as it can go on transom. More than likely it should be raised up a little. But it should work just fine where its mounted. It sure seems like the motor is to powerfull for the prop that is on it. As it seems to shoot up a rooster tail 15 feet behind the boat. It lifts the front of the boat up easily and then plows water. Then it either takes a long time to finnally plane out or it looses traction and starts blowing water up in the air 15 ft behind the boat and reving up. I know there must be a million bass boats with 115-150 hp motors on them. I am just asking what is a typical range of props for this type of set up. I can't believe some of them come with 11 pitch and some come with 26 pitch props? I would think there might be a pretty common starting point with this set up. Maybe 15 pitch or 21 pitch or 24 pitch. Thats all Im asking? Is the prop that I have on there within the typical range for a bass boat with a 140 hp Johnson? When we finnally get to a point of buying a prop I will take an afternoon and round up all the correct info needed as I think your program is absolutally awesome and it drives me nuts to see everyone ask for the perfect prop for their boat and only give you half the info needed.

Thanks
Scott

 

[hwsiii]

Re: pitch range?

Scott, if you will get a tach and hook it up I will see what I can run with some numbers for you.


H