prop problems

[fish 4 life]

I have a 1985 Ranger 335 Comanche with a 1978 140 HP Evinrude outboard that runs and sounds fine when running on land with the garden hose and motor flusher, but when in the water the RPMs go up to only about 2000 RPMs and would not get out of the hole. I did finally get the boat to plane out and was able to go about 50 MPH, but I was only able to plane the boat out after me and my brother sat at the very front of the boat while my father drove the boat. I weigh about 300 lbs and my brother weighs about 160, and my father weighs about 300 lbs. I thought maybe there was to much weight for the 13" X 19" stainless steel 3 blade prop. Do you know what could be the problem or problems? Do you think the prop is spun or not enough pitch or both?

 

[steelespike]

Re: prop problems

Motor performance on a hose means nothing except the motor runs.
Can you tell us what a 335 Comanche is;length,weight.
Was the speed by gps? Did it actually feel like 50mph.50 is pretty darn fast for any boat.Did you trim in all the way?Is the prop in excellent shape.Bottom clean?Based on your top speed I would say the boat may have absorbed water in the flotation foam under the floor.This usually concentrates extra weight right near the stern.You may want to put it on a trailer and weigh it.Compare to the manufactured dry weight.

 

[fish 4 life]

Re: prop problems

A 1985 Ranger 335 Comanche is a bass boat and it is 16.83 feet and should weigh about 1043 lbs dry and empty. I don't know exactly how fast the boat was going because the speedometer does not work, but trust me, we must have been going at least 45 mph. I use to have a 97 bayliner that was heavier and had a slightly smaller motor that would do 44 mph. We had to be going at least as fast as my old bayliner. The prop appears to be in great shape with no chips, digs, or unusual bends. My next move was going to be to take the prop to a prop specialist to see if it was spun. The bottom of the boat looks great. Where would I go to weigh my boat?

 

[hwsiii]

Re: prop problems

Fish, your problem is NOT a spun hub or you couldn't reach those speeds. You problem is the wrong blade geometry and/or pitch for the load you are carrying.
If you will fill this form out I will help you.

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 maximum 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. manufacturer 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 then do the same thing on the flywheel and turn the motor until the tape lines up with each other on the prop, 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, use a board under the keel and stiking out to the anti ventilation plate for a referene
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, number of blades 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. Make sure you trim the prop up until it starts ventilating and then just trim in until it quits ventilating. If you do not have a tach you can buy a digital tachometer and hour meter here: http://cgi.ebay.com/ebaymotors/Tacho...Q5fAccessories $ 35
RPM _________ Speed ______ GPS ______ No. of people ______ Gal. Gas ________
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 by just pushing the throttle at the helm and not at the carburetor, checked compression, and looked at the plugs and checked spark as well as timing and advance, all of the foregoing 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
19. If you are trying to attain a better cruising speed and fuel savings or trying to attain a faster speed I will want you to take your boat and run it with 1 or 2 people and give me the RPM and speed readings starting at 3,000 RPM in 500 RPM increments all the way to WOT.

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

 

[fish 4 life]

Re: prop problems

Thanks for the reply. I will try to answer all the questions to the best of my ability.

The WOT RPM is about 5,200 and the speed is about 50 MPH.

1. 1985 Ranger 335 Comanche bass boat
2. Length = 16.83. Width = 82 inches. dry weight = 1045 lbs
2a. Maximum Recommended HP is 140
3. 3 people, 770 lbs of people, and 20 gallons of gas normally in boat
4. boat is used primarily for fishing
5. boat is not a Deep Vee
6. Outboard motor is 1978 Evinrude 140 HP
7. unsure of gear ratio at this time
8. unsure of manufacturers WOT range
9. unsure of anti-ventilation plate height or what a anti-ventilation plate is
10. boat is a bass boat
11. boat does not have hydrafoil, dolefin or trim tabs
12. unsure of make and model of prop. prop diameter is 13. pitch is 19. 3 blade SS

13. WOT RPM = 5,200, Speed = 50 MPH. 3 people with 20 gallons of gas
14. 2,000 feet above sea level
15. motor was just tuned up with new carbs and stator. compression was good at 120. spark plugs and wires were good.

16. unsure of how long prop was on boat and why. I do think it is the wrong prop

17. no damage to prop from what I can see
18. I am trying to fix the problem of the boat not getting out of the hole properly without having to put over 450 lbs of people on the very front for the boat to plane out

 

[hwsiii]

Re: prop problems

Fish, if you will buy a Solas Amita 4 blade aluminum prop in a 19" pitch you will find that the boat will get on plane much faster. The 4th blade will help stop the cavitation and pick the stern of the boat up so the bow won't rise so high and make the stern dig a hole in the water. Since you have the extra blade it will also help prevent the cavitation you are experiencing trying to transition to plane, because of the extra blade surface area.


H

 

[fish 4 life]

Re: prop problems

I noticed the Solas Amita 4 blade aluminum prop is a 12.5 inch diameter prop, which is 0.5 inches smaller than the prop I got on the boat right now. Do you think this change in a smaller diameter prop is OK? Do you think I should drop down to a 18 or 17 degree pitch to help me get out of the hole? Also, are you recommending an aluminum prop for a performance reason or, are you just trying to save me money? I have always been told that a SS props are almost always better for better performance.

Thank you for all your help.

 

[72SideWinderSS]

Re: prop problems

Before you run out and by a New Prop, might I suggest telling us what type of trim you have? Manual, Hydraulic
Where is the Trim Pin Located i.e first hole out from the transom, second hole ...
I just hate to see someone spend that amount of money when it my not be necessary.

 

[hwsiii]

Re: prop problems

Fish, a small change in diameter does not have as much effect on thrust as does blade surface area and blade geometry, and I picked this prop for performance reasons, as I know what it does. A 17" pitch prop in the Solas Amita will raise your RPM to about 5,700 RPM and that will work fine as Dhadley says, I keep forgetting the old looper engines like high RPM and the excess RPM will not hurt the engine. And you are very right it will help the hole shot more, and you will probably only lose a couple of miles per hour.
If you would like a SS prop, just type Dhadley in the thread topic and I believe he can help you pik the best SS prop for you.


H

 

[fish 4 life]

Re: prop problems

SideWinder, I have hydraulic tilt and trim and the pin is in the first hole out from the transom.

I called around and I did have a couple of more people tell me that the foam in the boat might be soaked with water that has flooded in the boat in the past, causing the boat to raise the bow of the boat high and making it hard to get out of the hole. I am having someone drill some holes in the boat to see if there is water to be drained out.

 

[fish 4 life]

Re: prop problems

Good news, no water was found in the foam. I will try a prop with less pitch.

 

[fish 4 life]

Re: prop problems

I tried a 4 blade prop with a 17 inch pitch and the boat is doing the same thing. It will not plane out unless my brother and I sit at the front of the boat. I measured the the distance from the cavitation plate to the very bottom of the boat and the cavitation plate is about 3 inches higher than the bottom of the boat.

 

[72SideWinderSS]

Re: prop problems

Fish,
Things I would do/Check,
Link & Sync the carbs, Making sure the carbs are opening horizontal, and pickup timing is correct. Check timer base, that it is not sticking part way, has to go all the way to the rubber stop, check Max advance and set if needed.
Good Luck.

 

[fish 4 life]

Re: prop problems

I just had the engine checked out. New carbs were put in. The mechanic ran it on the dyno and he says the engine is running like a top. As for the carbs opening horizontal, pickup timing, timer base, etc, etc.... I can't say if those things are working properly, because I am not a mechanic and I am not sure what you are talking about.

 

[fish 4 life]

Re: prop problems

Ranger boats says I should try a 3 blade 14 X 17 aluminum prop or drill holes in my SS prop for better ventilation. What do you think?

Attached is a picture of the height of the motor.

 

[fish 4 life]

Re: prop problems

I went to the local prop shop and I talked to him about going down in pitch on a prop. He looked at my boat and he said the engine is too low and needs to be raised about an 1 or 1 1/2 inch. I told him I thought it was to high because the anti-cavitation plate was about 3 inches higher than the bottom of the boat. He said that not as big a deal as the prop being about 5 inches below the boat. He said the center of the prop should be no more than 4 inches below the boat and 3 inches for a four blade prop. He said the reason for my excessive bow rise is because the motor is too deep or too low.

Does this seem accurate?

 

[steelespike]

Re: prop problems

Sounds extreme to me.If your not experiencing any ventilation(cavitation)
now it wouldn't hurt to raise it and see what happens.Just be sure it pumps water.My usual advise is raise the motor to a point just before venting becomes a problem.

 

[fish 4 life]

Re: prop problems

Sounds extreme to me.If your not experiencing any ventilation(cavitation)
now it wouldn't hurt to raise it and see what happens.Just be sure it pumps water.My usual advise is raise the motor to a point just before venting becomes a problem.

How will I know if or when venting becomes a problem?

 

[steelespike]

Re: prop problems

Venting is when the prop loses its grip motor revs boat slows or stops gaining speed.

 

[hwsiii]

Re: prop problems

Fish, exatly whih 4 blade prop did you try on the boat, I would like to know the manufaturer as well as the model.

I tried a 4 blade prop with a 17 inch pitch and the boat is doing the same thing. It will not plane out unless my brother and I sit at the front of the boat. I measured the the distance from the cavitation plate to the very bottom of the boat and the cavitation plate is about 3 inches higher than the bottom of the boat.

H