Prop for 1993 Wellcraft Excel - help please

[Greebo]

Hi there,
This is my first post.
I have searched the forum but can't find an answer to this problem.
I own a 1993 Excel 18SX I/O which is fitted with a 2.3L Volvo Penta sterndrive. This boat is a direct import from USA (including an Arrow trailer) and no-one in Australia seems to know much about it.
Volvo would be happy to sell me a new motor and leg, but that is simply not financially possible.
I am very disappointed with it's performance, the boat struggles to get to 30MPH at WOT and 5 000 RPM and doesn't accelerate well at all. It wouldn't pull the skin off a custard let alone pop a skier out of the water.
I thought that was normal, until I did an Internet search and found the Wellcraft site.
According to this site I should be getting about 27 MPH at 3 000 RPM and in excess of 43 MPH at 5 000 RPM. I just wish.
I am presently running a 15X17 prop.
I have drained the fuel and replaced the fuel filter, I have changed to premium ULP (98 octane)to see if that would help.
I am having the carbi checked and overhauled by an expert, and am fitting a electronic ignition, new coil, plugs and HT wires.
Compression seems OK.
Before I water test it, I would like to know what prop was fitted to the boat from new.of that size I would like to fit a prop to start with, assuming the boffins at Wellcraft knew what they were doing when they designed the boat.
Can anyone help?
Does anyone in the forum own this combination who can advise what their experience with this rig is?
Any help at all would be greatly appreciated.
Greebo

 

[steelespike]

Re: Prop for 1993 Wellcraft Excel - help please

I'm sure someone will be along with more spercific info but speaking generically.
Be sure the throttle is opening all the way.Be sure it is running on all cylinders.
Hopefully the work your having done will solve some of these suggestions.
You might weigh the boat and compare it to the manufactured weight.
Do you know the gear ratio?We will need that.Based strictly on the size of the boat,the small displacement and the 5,000 rpm rating my guess is the 17 is about right.You should check your speed by gps.regular speedo could be off 5 mph either way.You should confirm your tach is accurate.Its a little puzzling poor performsance but reaching max rpm yet only 30 doesn't add up.Are you trimming out for best speed?Trimming in for hole shot?Bottom clean?
Go back to regular gas.

 

[hwsiii]

Re: Prop for 1993 Wellcraft Excel - help please

Greebo, I ran some preliminary numbers guessing weight and other factors including motor HP and I could only come up with a maximum of 38 MPH, but if you will fill out this form I will do what I can to see what prop and speed you should be running. But you also need to follow all of Spike's advice to be sure there are not other problems.

You also might try reading this for a better understanding of changing props for better performance.

http://forums.iboats.com/showthread.php?t=365653"]http://forums.iboats.com/showthread.php?t=365653"]http://forums.iboats.com/showthread.php?t=365653

Welcome, I will try to help you as much as I 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 humanly possible, if you would prefer to not go to this much trouble there are other people who will gladly help you. My expectations are that you are willing to expend as much time and energy as I will to find a better prop for your boat.

Just copy this form to your computer and paste it into a word processing program and fill it out, then paste it into your post.

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, 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 the bottom of the transom of boat if it is an outboard in inches, use a straight edge or a board under the keel and sticking out to the anti ventilation plate for a reference, and take about 4 pictures for us to see.

10. Is it a bass boat or does it have a pad bottom

11. Does it have a hydrafoil, dolefin or trim tabs

12. Manufacturer, model, diameter, pitch, number of blades and whether SS or aluminum props.
IMPORTANT
1.
2.
3.

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 Tiny Tach for less than $ 50
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 only using the control on the console, checked compression, looked at the plugs and checked spark, is the bottom of the boat clean and barnacle free, and have you checked the Tachometer against a mechanics tach, 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.
1. 3000 RPM
2. 3500 RPM
3. 4000 RPM
4. 4500 RPM
5. 5000 RPM
6. 5500 RPM
7. 6000 RPM

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

 

[Greebo]

Re: Prop for 1993 Wellcraft Excel - help please

Thanks, I'll do all this. I will need to wait until I get the boat back in the water after making all the other adjustments.
It might take a week or so. That is why I was hoping to at least find out what prop the manufacturer fitted to the boat to give me a baseline to start from.
Greebo.

 

[Tail_Gunner]

Re: Prop for 1993 Wellcraft Excel - help please

http://www.wellcraft.com/owners/infoguides/1993/EXCEL_PIG_18SX_IO_Bowrid_93.jpg

Prior to any prop changes a few things....Make sure your engine is fully tuned...verify your tach is accurate....finally verify your speed with a gps system .

The very fact your readings give you 5000 rpm @ 30 mph would indicate a spun hub..... aka slow out of the hole (hub over spinning) and yet pushes the boat to 5000.(healthy motor) slip shows 27% slip @ WOT way to much for that hull.

http://www.go-fast.com/Prop_Slip_Calculator.htm Use a gear ratio of 1.98 or 2.0 pretty std for a smaller 4cyl motor.

So verify the rpm gauge and the true speed and if there correct find a temporary prop and do another run.

http://maps.google.com/maps?hl=en&s...code_result&ct=image&resnum=1&ved=0CAwQ8gEwAA

Your @ sea level dont worry about elevation.. But do check and clean your hull thourghly

 

[Greebo]

Re: Prop for 1993 Wellcraft Excel - help please

Well, you are definitely right about about the slipage. I managed to get the boat on the water today and have 'spun' the prop. One difficulty with shallow water running I guess.
I have finally got the motor running as it should. I've had the carby reconditioned, put in an electronic ignition system with new coil, HT leads and plugs and replaced the timing belt.
That was interesting. The timing belt was about 40 deg out. When I had the boat serviced and tuned by an 'expert' he mentioned in his account that he had changed the ignition timing 40 deg. It's a shame he didn't try and find out why.
Anyway, I get the prop fixed and then will be in a position to try again.
It is so nice to have the benefit of you guys advice.
I'd still like to find out what ratio prop was orginally fitted, or what is a success with other boats.
I'll get this sorted yet.
Greebo

 

[Greebo]

Re: Prop for 1993 Wellcraft Excel - help please

These are the figures I came up with yesterday. The boat is running well on the second prop and jumps onto the plane readily.

1. Year, make and model of boat
1993 Wellcraft Excel 18SX I/O Bowrider

2. Length, width and base weight of boat, look for boat decal on back of boat
Centreline 18 ft
Beam 7?2?
Base weight 1,900 lb (from manufacturer)

2a.What is the maximum recommended HP for your boat
Boat was ?turnkey?. Is fitted with a Volvo Penta AQ230A (120hp at crank, 110 at prop)

3. Number of people and gallons of gas normally on boat
4 persons ? 20 gallons US

4. What do you use the boat for
Cruising, pulling ?tubes? and a little skiing

5. Is it a Deep Vee and if so how many degrees of Deadrise
Not a deep V : deadrise is 18 deg

6. Year, manufacturer and model of motor
1993 Volvo Penta AQ230A

7. HP and gear ratio of motor IMPORTANT
110HP at prop : ratio 2.15
8. Manufacturer?s recommended Wide Open Throttle (WOT) range
4,800 to 5,000 RPM

9. Anti-ventilation Plate height above the bottom of the transom of boat
pretty well flush



10. Is it a bass boat or does it have a pad bottom
Don?t know what you mean ? seems to be a easy planning hull if that helps

11. Does it have a hydrafoil, dolefin or trim tabs
No

12. Manufacturer, model, diameter, pitch, number of blades and whether SS or aluminum props.
IMPORTANT
1. Make unknown, but possibly Solas brand 16x17 aluminium
2. Volvo Penta 14x19 aluminium


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.

RPM 5,800 both props Speed (GPS) Prop 1 - 31 MPH Prop 2 - 38 MPH
No. of people: Prop 1 - 2 people Prop 2 - 3 people
Gas about 15 gal US

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 by only using the control on the console, checked compression, looked at the plugs and checked spark, is the bottom of the boat clean and barnacle free, and have you checked the Tachometer against a mechanics tach, all of the foregoing could be the reason your prop is not attaining full RPM.

Yes ? appears all OK

16. How long has this prop been on the boat and why, at this time, do you think it is the wrong prop.
(1) Prop 1 - a couple of years ? the motor was always low on power and that has just been resolved (timing belt was about 40 deg out). Now have much more power than previously
(2) Prop 2 is a new prop

17. Does the prop show any damage that you can see
(1) Prop 1 -Some minimal wearing from striking sandy bottom, but otherwise AOK
(2) Prop 2 - new

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:
Poor performance overall. The manufacturer stipulated 43.5MPH @ 5,000 RPM and 27.3 MPH at 3,500 RPM ? boat has previously been unable to achieve 30 MPH @ 5,000 RPM WOT using 16x17 and 15x15 props.
The motor was found to be in a very poor state of tune (about 40 deg out). Now has had a carbi overhaul ; new HT leads, plugs and coil; electronic ignition and timing has been corrected. Now runs well.

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.

Prop 1 (2 people) Prop 2 (3 people)
1. 3000 RPM 13 MPH 9.9 MPH off plane
2. 3500 RPM 22 MPH 18.5 MPH
3. 4000 RPM 25 MPH 24.8 MPH
4. 4500 RPM 27 MPH 28.9 MPH
5. 5000 RPM 29 MPH 33.2 MPH
6. 5400 RPM 31 MPH 35.7 MPH
7. 5800 RPM (WOT) 31 MPH 38 MPH

I guess the question I now need to answer is do I stick with the 14x19 prop, or go higher.
Volvo Penta states that a 14x19 has a speed range of 31 - 37 MPH (and I'm slap in the middle of that). But as you can see from my performance figures, I can pull about 800 RPM over the recommended operating range with this prop.
Volvo brochures have this information for this motor/leg.
a 15x17 is good for 30 - 36 MPH
a 15x19 gives 36 - 42 MPH and
a 14x21 gives 38 - 43 MPH.
I still want to be able to plane fully loaded, and perhaps pull a single skier or a tube.
I'm thinking keep this prop, and perhaps also get a 15x19.
Robj has an identical boat. He uses a 15x17 (uncupped for skiing, cupped for cruising).
Any advice would be appreciated.
Regards
Greebo

 

[hwsiii]

Re: Prop for 1993 Wellcraft Excel - help please

Peter, I have questions when I see you have a 16" diameter prop with 17" pitch turning the same exact RPM as a 15" diameter 19" pith prop doing the same thing. The difference can be because of the difference in diameters, as there is a 1" difference in diameter and there could be differences in blade geometry as well.

But my first question is do you know positively that your tach is right, because I am showing MAJOR prop slip for such a small light boat with a 16" diameter prop. I am showing your prop slip to be 29% for the 17" pitch prop and 22% for the 19" pitch prop. My thoughts are running the same as Tail_Gunner, in that I QUESTION the RPM reading and are these numbers by GPS. You should NOT be having prop slip anywhere near those numbers with these props.


Numbers

Prop Slip

charts

By looking at the above charts it appears to me that you have a slipping hub in the 17" pitch prop, and the reason I say this because you can see that the prop slip starts going up again even after you get the boat on plane, and it should be going down normally, like it is on the 19" pitch prop.

Effective Prop Pitch

Please verify the tach is right using a mechanics tach on the motor when you are running it on the water, and if this is not GPS readings we need true GPS readings to find the problem. I find it very hard to believe you are really experiencing prop slip that high with this boat.

If you will look at the effective prop pitch for both of your props you will see that the 17" pitch only has an effective pitch of 12" and the 19" pitch only has an effective pitch of 14.9" and that is because of the high prop slip you have.




H

 

[Greebo]

Re: Prop for 1993 Wellcraft Excel - help please

Thanks.
I see what you mean.
I'll try another tacho (in a fortnight unfortunately) and see if this changes my figures. I was using a GPS but found it very hard, almost impossible, to hold revs accurately for any length of time.
I was surprised that the motor wouldn't pull more than 5 800 RPM with either prop. I knew that that was over reving the motor but it didn't seem to be valve bouncing or over stressed. As this is basically a car motor I feel these revs should be OK for a short time.
The 17" prop could be slipping as you say, it's had a hard life.
I have a new 15 x 15 available to try - I didn't because it was such a low pitch. But if I use this will it give you meaningful figures to work on?
Thanks again for all the help.
Regards
Peter

 

[Greebo]

Re: Prop for 1993 Wellcraft Excel - help please

Thanks.
I see what you mean.
I'll try another tacho (in a fortnight unfortunately) and see if this changes my figures. I was using a GPS but found it very hard, almost impossible, to hold revs accurately for any length of time.
I was surprised that the motor wouldn't pull more than 5 800 RPM with either prop. I knew that that was over reving the motor but it didn't seem to be valve bouncing or over stressed. As this is basically a car motor I feel these revs should be OK for a short time.
The 17" prop could be slipping as you say, it's had a hard life.
I have a new 15 x 15 available to try - I didn't because it was such a low pitch. But if I use this will it give you meaningful figures to work on?
Thanks again for all the help.
Regards
Greebo

 

[hwsiii]

Re: Prop for 1993 Wellcraft Excel - help please

Peter, the main thing I am interested in is the RPM and speeds by GPS, just like you did last time except with a different tach.

I'll try another tacho (in a fortnight unfortunately) and see if this changes my figures. I was using a GPS but found it very hard, almost impossible, to hold revs accurately for any length of time.

I can understand the problem with the 17" and the hub slipping, but that doesn't make sense with the 19" pitch, can you explain exactly what you mean by not being able to hold the revs for any length of time.

I have a new 15 x 15 available to try - I didn't because it was such a low pitch. But if I use this will it give you meaningful figures to work on?

No, I don't need the results from the 15" pitch. But I would like about 3 pictures of each of the two props, and you are very welcome.



H

 

[Tail_Gunner]

Re: Prop for 1993 Wellcraft Excel - help please

verify the tach...That should clear a lot up..I not to sure that old motor can even hit 6000

 

[Greebo]

Re: Prop for 1993 Wellcraft Excel - help please

Once again you were right Tail_gunner and hwsiii.
The tacho was way out. I've replaced several instruments due to their age - I might need to replace the tacho as well.
I've run some more figures one-up using a mechanics tacho and a GPS. It was fairly choppy so there will be some variation in my figures due to the difficulties I had in maintaining a steady speed due to the water conditions. But to my inexperienced eye the figures seem to be much more consistent with revs/speed ratios.
These were taken with a brand new Volvo Penta brand 14x19 prop.
RPM Mph
3,000 18.6
3,500 22.7
4,000 26.3
4,500 31.5
5,000 37.1.
Broadly speaking, this seems to be about 3.6 to 3.7 Mph/500 rpm.
And you were right, the motor struggled to get much over 5,000 rpm.
It would seem to me that this is probably close to being the right prop, although I could possibly at a pinch try either a 15x19 or perhaps a 14x21 if I really want to achieve a slightly higher top speed. I am concerned, however, that if I do that I might well be 'over proping'.
Speeds quoted by the manufacturer when new were 43.5 Mph at 5,000 rpm and 27.3 Mph at 3,500 rpm. These look consistent to what I would expect with no slippage with a 19" pitch.
Anyway, I look forward to your expert comments.
Regards
Greebo

 

[Tail_Gunner]

Re: Prop for 1993 Wellcraft Excel - help please

So you can hit 5000 rpm with the 19...Was that with a load or just yourself..How many people were aboard.

 

[hwsiii]

Re: Prop for 1993 Wellcraft Excel - help please

Greebo, It appears that the prop you have on there right now is very good, your prop slip is at 11% which is fine. If you are having a problem with head seas and they keep slowing the boat down and you have to keep jockeying the throttle, then you might want to consider buying a 4 blade prop to stop that. I ran a couple of harts for you to look at.

Prop Slip

Effective Prop Pitch

H

 

[Greebo]

Re: Prop for 1993 Wellcraft Excel - help please

That's what I figured to.
Am very pleased with the new performance of this rig.
Thanks again for all your input.
It was much appreciated.
Now all we need is some more rain in the catchment areas of the Murray River so that I have more water to play with.
Regards
Greebo

 

[hwsiii]

Re: Prop for 1993 Wellcraft Excel - help please

You are very welcome Greebo, and I wish you luck with the water rising. LOL


H

 

[180shabah]

Re: Prop for 1993 Wellcraft Excel - help please

You can pretty much ignore the builders speed claims. They were done with a new engine, probably in perfect water conditions with minimal fuel and gear. Your speed now sounds pretty good for the "real" world.