hwsiii
Commander
- Joined
- Jan 25, 2009
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Kenny?s Prop Tests and an Analysis
I took all of Walleyehed?s ( Kenny Sanderson) prop test results and ran a complete analysis of his results to see what kind of information I could extract that might be useful to all of us. I tried to do the analysis in most cases by using the props that were only run in one day and in the same general conditions as each other as that is the way he did it and I believe it is the right way. I left some of the props out as I couldn?t find the exact model to be able to know which exact prop it was. In my opinion we can take this data and create some overall theories about the differences in the props that he ran and this will be helpful when we are trying to get every last MPH out of our boat and motor, or need to increase the RPM up to our recommended WOT operating range without losing any speed or decrease the RPM to fall within our recommended operating range or find the right prop that will decrease our Prop Slip and thus give us an increase in speed. These can only be generalizations but they are excellent generalizations as I doubt very many people have the exact same setup that he had on his boat. BUT everyone of these props was used on the same boat and motor combination which definitely gives us an advantage in that we are comparing apples to apples as far as the boat and motor setup goes. He refilled the tank after every test and jacked up all the motors on the jackplate until they started to ventilate too much. He also added extra weight to test the lower pitch props and try to help simulate heavier cruisers, he added less weight the higher the pitch range he was testing.
From my understanding of reading his post this is the setup on his boat that he used:
Brand, Year Model of Boat Best guess from TG is Starcraft Sportsman
If anyone knows please send me a PM so I can post it I used 1809 FS
Length 18?
Hull Form Deep Vee
Hull Material Aluminum
Allup Boat Weight 2,400 pounds My best guess without any added sand tubes
Motor Modifed 242 HP Evinrude 1.86 Gear ratio that can handle RPM over 7,200
Jackplate 6? setback on jackplate
Trim Tabs Nauticus Mobster Tabs
The following is my analysis and interpretation of his tests and how they can help us in determining what prop and pitch we need for our boats. By using the same platform for his tests it does give us a basis for comparing one propeller to another in the same pitch and tells us what we can expect in the differences in Theoretical Speed, RPM and Prop Slip. I did my analysis by running the numbers for Speed, RPM and Prop Slip and then making charts so it is easier to see the differences instead of just looking at numbers and trying to remember them. In some cases we find that props having the exact same RPM do not have the same speed because of Prop Slip differences and in other cases we find that props with lower RPM actually are faster than the one with higher RPM because the prop slip is not near as much as the higher RPM prop. In theory if you have a boat with a prop that turns too many RPM you an change to another prop of the same pitch but different blade geometry and decrease your RPM while at the same time increasing your speed, and the exact opposite can be true too. These correlations can be very helpful to us in fine tuning our boats to maximize our recommended RPM range to the top of the range and thus improve fuel consumption and put less strain on the motor overall as well. These theories will only work on the exact props designated in the following charts and you have to remember as well that a lot of props have much of the final finish work done by hand, so you can experience results that are unexpected at times, in cases like this I would recommend trying another exact pitch prop of the same make and model and check the results again. To have the props come from the factory exactly the same would require that all props be tested and lab finished and reconfigured to the exact specifications that the manufacturer designed the prop at and you do not get that when you buy a prop but they are very close in almost all cases.
My analysis of the different props and the comparisons starts below. I also will insert Ken?s comments on each prop as his observations are very meaningful to the testing. I sent Ken a PM awhile back to try and gather more information from him diretcly about his boat and his testing but evidently he hasn?t been here in a while and I did not hear from him, but I feel his tests are very important to all of us and so I decided to post the charts without waiting any longer. Hopefully he will test some of the newer models of props and we can do some more analysis to add to these results. In theory the following results and analysis will have a more direct relationship to deeper vee boats, but by Ken adding the mobster tabs to the boat the results created a more universal hull form than just deep vee boats.
15? Pitch Props
I took all of Walleyehed?s ( Kenny Sanderson) prop test results and ran a complete analysis of his results to see what kind of information I could extract that might be useful to all of us. I tried to do the analysis in most cases by using the props that were only run in one day and in the same general conditions as each other as that is the way he did it and I believe it is the right way. I left some of the props out as I couldn?t find the exact model to be able to know which exact prop it was. In my opinion we can take this data and create some overall theories about the differences in the props that he ran and this will be helpful when we are trying to get every last MPH out of our boat and motor, or need to increase the RPM up to our recommended WOT operating range without losing any speed or decrease the RPM to fall within our recommended operating range or find the right prop that will decrease our Prop Slip and thus give us an increase in speed. These can only be generalizations but they are excellent generalizations as I doubt very many people have the exact same setup that he had on his boat. BUT everyone of these props was used on the same boat and motor combination which definitely gives us an advantage in that we are comparing apples to apples as far as the boat and motor setup goes. He refilled the tank after every test and jacked up all the motors on the jackplate until they started to ventilate too much. He also added extra weight to test the lower pitch props and try to help simulate heavier cruisers, he added less weight the higher the pitch range he was testing.
From my understanding of reading his post this is the setup on his boat that he used:
Brand, Year Model of Boat Best guess from TG is Starcraft Sportsman
If anyone knows please send me a PM so I can post it I used 1809 FS
Length 18?
Hull Form Deep Vee
Hull Material Aluminum
Allup Boat Weight 2,400 pounds My best guess without any added sand tubes
Motor Modifed 242 HP Evinrude 1.86 Gear ratio that can handle RPM over 7,200
Jackplate 6? setback on jackplate
Trim Tabs Nauticus Mobster Tabs
The following is my analysis and interpretation of his tests and how they can help us in determining what prop and pitch we need for our boats. By using the same platform for his tests it does give us a basis for comparing one propeller to another in the same pitch and tells us what we can expect in the differences in Theoretical Speed, RPM and Prop Slip. I did my analysis by running the numbers for Speed, RPM and Prop Slip and then making charts so it is easier to see the differences instead of just looking at numbers and trying to remember them. In some cases we find that props having the exact same RPM do not have the same speed because of Prop Slip differences and in other cases we find that props with lower RPM actually are faster than the one with higher RPM because the prop slip is not near as much as the higher RPM prop. In theory if you have a boat with a prop that turns too many RPM you an change to another prop of the same pitch but different blade geometry and decrease your RPM while at the same time increasing your speed, and the exact opposite can be true too. These correlations can be very helpful to us in fine tuning our boats to maximize our recommended RPM range to the top of the range and thus improve fuel consumption and put less strain on the motor overall as well. These theories will only work on the exact props designated in the following charts and you have to remember as well that a lot of props have much of the final finish work done by hand, so you can experience results that are unexpected at times, in cases like this I would recommend trying another exact pitch prop of the same make and model and check the results again. To have the props come from the factory exactly the same would require that all props be tested and lab finished and reconfigured to the exact specifications that the manufacturer designed the prop at and you do not get that when you buy a prop but they are very close in almost all cases.
My analysis of the different props and the comparisons starts below. I also will insert Ken?s comments on each prop as his observations are very meaningful to the testing. I sent Ken a PM awhile back to try and gather more information from him diretcly about his boat and his testing but evidently he hasn?t been here in a while and I did not hear from him, but I feel his tests are very important to all of us and so I decided to post the charts without waiting any longer. Hopefully he will test some of the newer models of props and we can do some more analysis to add to these results. In theory the following results and analysis will have a more direct relationship to deeper vee boats, but by Ken adding the mobster tabs to the boat the results created a more universal hull form than just deep vee boats.
15? Pitch Props
All of the 15? pitch props in these tests had 800# of sand bags, 400# in stern, 200 # in bow and 200 # in the passenger seat added to the boat to try and simulate a heavier cruiser and provide more realistic results in that category
So the theoretical Allup boat weight was approximately 3,500 # + 800 = 4,300 #
The Michigan Wheel prop is model number 013052
The other two are the Solas Lexor and the Mercury Mirage+
The Michigan Wheel prop provided the highest speed, highest RPM and had the same prop slip as the Mirage+ with the lowest speed the Mirage+
The Lexor has a midrange speed with lowest RPM but the lowest prop slip of the three
In theory if you have a boat with a Lexor Prop and it was producing low RPM you could change to a Michigan wheel to get your RPM and speed up to the top RPM range and maximum speed
The inverse of this is that if a prop were turning too many RPM you could change props from the MWC or the Mirage+ to the Lexor and lose very little speed but decrease your RPM to a better range
There is a 300 RPM range difference in these props but yet very little difference in Speeds because of prop slip.
17? Pitch Props
All of the 17? Pitch props were tested with 800# of extra sand added to the boat 400# in stern, 200 # in bow and 200 # in the passenger seat added to the boat to try and simulate a heavier cruiser and provide more realistic results in that category
So the theoretical Allup boat weight was approximately 3,500 # + 800 = 4,300 #
The fastest Prop was the Turbo1 at 50.9 MPH and the slowest was the Lexor at 45.2 MPH
The Turbo1 and the Stiletto produced the highest RPM at 6,300 and the lowest RPM 6,150 was the Ballistic
The Turbo1 had the least Prop Slip at 6.7% and the Lexor the highest at 16%
The difference between the lowest speed and the highest speed is 5.7 MPH
The difference between the lowest RPM and the highest is only 150 RPM
The difference between the lowest and highest Prop Slip is 9.3%
The Turbo1 appears to be the best prop of the group with the highest speed, the highest RPM and the lowest Prop Slip of all the props
The Lexor appears to be the worst prop of this group with a top speed 5.7 MPH below the Turbo1 and only 150 RPM below the Turbo1 and the lexor has a prop slip of 16% the highest of all the props
It appears that changing between any of these props does not considerably affect the RPM much but it does appear to change the boats maximum speed considerably because of differences in the amount of prop slip experienced by each prop.
18? and 19? Pitch Props
All of the 19? Pitch props were tested with 200# of extra sand added to the boat in the passenger seat
So the theoretical Allup boat weight was approximately 3,500 # + 200 = 3,700 #
The fastest was the Enertia at 54.4 MPH and the slowest was the SST at 52.1 MPH and there is very little difference in speeds
The highest RPM produced was by the Stiletto and Rapture at 6,000 RPM and the lowest RPM was the Apollo at 5,910 RPM
The lowest Prop Slip was the Enertia at only 6.1% Prop Slip and the highest was the SST at 11.7%
All of the props were within 2.3 MPH of each other, the RPM were within 90 RPM but the prop slip varied from 6.1% all the way to 11.7% with the SST
The best prop of the group appears to be the Enertia 19? as the speed attained was 54.4 MPH and the RPM was at 5,990 with the lowest Prop Slip of all the 19? props tested. But the Enertia 18? at 53.1 MPH is only 1.3 MPH slower than the Enertia 19? and only a 30 RPM difference but has 2.4% less prop slip and is as fast or faster than all the other 19? props in this category.
The worst prop of the group appears to be the SST as the speed was 52.1 MPH at 5,960 RPM and the prop slip was 11.7%.
20? and 21? Pitch Props
All of the 21? Pitch props were tested with 200# of extra sand added to the boat in the passenger seat
So the theoretical Allup boat weight was approximately 3,500 # + 200 = 3,700 #
The fastest prop in this group was the Turbo at 55.4 MPH, but that is only a 1 MPH faster speed than the Enertia 19? and a 290 RPM decrease in RPM for the Turbo 21? as well as an increase of 3% in prop slip, so my assumption is the Enertia has a theoretical 2? increase in pitch probably created by more cup in the prop and is easier to turn. I believe that in most cases the Enertia 19? would perform better with higher RPM and thus less load on the motor and the prop slip is better than the rest of the props in this test of 21? props.
The Raker 20? is faster than all of the other props except the Turbo 21?, the RPM is only 100 RPM more than most of the other props, but the prop slip is very low at only 7.4%.
The worst prop in this test was the Ballistic as it attained only 53.2 MPH at 5,700 RPM and had a prop slip of 12.7% while the Enertia 19? has a prop slip of only 6.1% with a speed of 54.4 MPH and the turbo 21? only has a prop slip of 9.1%.
High Pitched Props
All of the 21? and higher Pitched props were tested with 200# of extra sand added to the boat in the passenger seat
So the theoretical Allup boat weight was approximately 3,500 # + 200 = 3,700 #
The fastest prop in this category is the Tempest 26? at 57.3 MPH and 4,950 RPM with a prop slip of only 12.6%, but the Scorpion 24? is a close second with a speed of 56.3 MPH and RPM of 5,250 with a prop slip of 12.2%.
The prop slip for all props with a pitch of 22? or more ranges from a low of 12.2% to a high of 15.4% in the higher pitches.
Heavy Load Props
I do not know how much weight was in the boat for these tests, if anyone knows please tell me so I can post it and everybody can have the information.
All of the props tested in this category are from 15? pitch to no larger than a 21? pitch and the RPM vary from a low of 5,500 RPM to a high of 6,550 RPM and a low speed of 41.9 MPH to a high speed of 49.1 MPH.
Without knowing how much weight the boat was carrying at this time it is hard to make an analysis of exactly how good these props are, though we can note the differences even without that knowledge.
The forum will not let me post more than 6 images at a time, so I will add the other data later.
H
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