Here's the torque curve overlay I was thinking of:
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| Ballast has me stumped???? Boat can't get out of its own way http://www.axiswakeboardboats.com/viewtopic.php?f=15&t=3651 |
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| Author: | shawndoggy [ Mon May 23, 2016 10:01 am ] |
| Post subject: | Re: Ballast has me stumped???? Boat can't get out of its own |
WayneTuttle wrote: Size Matters, and bigger is not always better. The larger diameters apply more torque loading on the shaft, but have better RPM-to-Speed relationships. But we all have cruise control, so it is not that critical. I would drop your diameter to free up the RPMs and the additional slippage will not be an issue. My prop shop came up with a 13.5 X 14 for me that works great for me on my '14 A22 w/330. Tons of punch out fo the hole, and surfing and boarding is great. I never go above 30 MPH anyway, but that is about 3700 RPM. We can surf/Wakeboard/Ski all day (6 or 7 hours of towing) and still have more than 1/4 tank of gas. I could not be happier. BTW surfing and wakeboarding all are in the mid 3000 range. Unless we are skiing or tubing all tanks are full. We have the big Arrow sac in front (1,100?) and 750's in the rear. Wedge only used for surfing. YMMV Haha, dude you are at sea level! If you have ever gone backwards in diameter (say from a 15" prop to 14.5" or smaller) you would know that size definitely DOES matter. I tried going backwards from a 2315 to a 2079 for exactly the reasons you state -- to get the rpms up. Problem being in practical application, yes the rpms came up, but forward thrust was not improved (all slip all the time). Boat went to feeling like a camaro with bald tires in the snow. That was on a 2011 MB 23, but I don't see why the result would be different on a different boat. |
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| Author: | shawndoggy [ Mon May 23, 2016 10:50 am ] |
| Post subject: | Re: Ballast has me stumped???? Boat can't get out of its own |
Here's the torque curve overlay I was thinking of:
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| Author: | r33pwrd [ Mon May 23, 2016 11:22 am ] |
| Post subject: | Re: Ballast has me stumped???? Boat can't get out of its own |
Really I think the best thing you can do is call one of the prop builders and explain them your situation. I'm sure you are not the first person with this problem. Sent from my SAMSUNG-SM-G925A using Tapatalk |
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| Author: | 2016A22inCO [ Mon May 23, 2016 8:35 pm ] |
| Post subject: | Re: Ballast has me stumped???? Boat can't get out of its own |
Boostedsled wrote: What RPM's are you pulling full throttle and no weight? What speed exactly is this? Thanks for the videos. Helps a lot. The 350's need to be 5000rpms wide open. I believe the 6L is around 5200rpms. You are way short of being there. Check the codes in the main menu as suggested too. Make sure it comes back empty/clear. No codes in the computer - I checked Check out the video I just recorded tonight. 35mph top speed. 5600-5700rpm running full throttle at top speed. https://vimeo.com/167829070 |
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| Author: | 2016A22inCO [ Mon May 23, 2016 8:39 pm ] |
| Post subject: | Ballast has me stumped???? Boat can't get out of its own way |
shawndoggy wrote: Here's the torque curve overlay I was thinking of: these are helpful I appreciate seeing the power curve differences in the motors. Kinda makes me wonder why didn't they do the 1.72 Trans for all motors?The plan is now that I have all of the answers I think I need for Eric at OJ I'll give him a shout tomorrow and get his take. Guys know that I REALLY APPRECIATE the help. |
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| Author: | Walter [ Mon May 23, 2016 10:09 pm ] |
| Post subject: | Ballast has me stumped???? Boat can't get out of its own way |
I agree with waynetuttle, I'd think a smaller diameter prop may help, the engine can't make enough torque to push the prop past 3500 rpm at that weight, a smaller diameter prop would give you more slippage at the same speed giving you a little more rpm and maybe the engine can horsepower past the hump you're hitting, see if your dealer can loan you a 2079 or 1615 to try out, if nothing else it's worth a try to find out, hopefully your prop guy can swap it for ya |
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| Author: | WayneTuttle [ Tue May 24, 2016 3:57 pm ] |
| Post subject: | SIZE MATTERS |
[quote]Haha, dude you are at sea level! If you have ever gone backwards in diameter (say from a 15" prop to 14.5" or smaller) you would know that size definitely DOES matter. I tried going backwards from a 2315 to a 2079 for exactly the reasons you state -- to get the rpms up. Problem being in practical application, yes the rpms came up, but forward thrust was not improved (all slip all the time). Boat went to feeling like a camaro with bald tires in the snow. That was on a 2011 MB 23, but I don't see why the result would be different on a different boat.[/quote] There is always more to it than just changing the diameter, the pitch is also critical. To go from a 15 X 12 to a 14 X 12 would not be ideal since the water being thrown is not increasing. a 14 X 14-1/4 might have been a nice balance between reduced shaft load and increased thrust. At these speeds and weights, I have never been convinced that the cup is as critical as pitch, since we are always going to have significant [b]slip under heavy load. As the boat is unweighted for the drive home, the cup can help the upper speeds.[/b] |
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| Author: | shawndoggy [ Tue May 24, 2016 5:54 pm ] |
| Post subject: | Re: Ballast has me stumped???? Boat can't get out of its own |
Wayne, I had run that exact prop (acme 1433, and it's 14.5" counterpart, the venerable 1235) on the boat before the 2315 and 2079. 2315 was night and day better for hole shot running heavy, and the 2079 was still better than both of the taller props as well. A small diameter prop definitely has more top end, but for pushing weight at wakeboard and surf speeds, especially at altitude, diameter matters. a lot. in my real life experience, anyhow, running at 4-5000'. |
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| Author: | 2016A22inCO [ Tue May 24, 2016 6:40 pm ] |
| Post subject: | Re: Ballast has me stumped???? Boat can't get out of its own |
shawndoggy wrote: Wayne, I had run that exact prop (acme 1433, and it's 14.5" counterpart, the venerable 1235) on the boat before the 2315 and 2079. 2315 was night and day better for hole shot running heavy, and the 2079 was still better than both of the taller props as well. A small diameter prop definitely has more top end, but for pushing weight at wakeboard and surf speeds, especially at altitude, diameter matters. a lot. in my real life experience, anyhow, running at 4-5000'. This essentially was echoed when I talked to Eric today at OJ. He told me that absolutely going to a smaller diameter would increase the RPM but to your point Shawn the size is really what gives you the push to move the weight. The resolution that we came up with is to ship the prop back to him and he's gonna take some cup out of the prop. That will add some RPM and hopefully get me to the sweet spot I am after for max power + torque in the 6.0 I went out tonight and filled the bags to full then drained the rears until the boat would plane. When enough weight was out that it would allow the boat to tip just a little and the RMP to climb to above about 3800 the "grunt in the motor" and its ability to move the boat was night and day and it planed quickly thereafter. My hope is after getting the prop worked over and adding some bow weight I may have it figured out. Fingers crossed. |
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| Author: | r33pwrd [ Tue May 24, 2016 7:41 pm ] |
| Post subject: | Re: Ballast has me stumped???? Boat can't get out of its own |
Want to sell your 2419? Sent from my SAMSUNG-SM-G925A using Tapatalk |
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