Oil Pattern Depletion
Oil pattern depletion (breakdown) is much different with today’s high flaring balls versus the low flaring balls of the past. Oil pattern depletion also happens much quicker and much more with today’s bowling balls.
When bowling balls had essentially balanced weight blocks, or differential Rg values of .010” or less, the ball basically rolled over the same place every revolution. When this happens, the ball picks up all the oil it can within the first couple revolutions and oil pattern depletion only happens in the head area, or only in the first 16’. The rest of the oil pattern remained intact, but not with today’s high differential Rg weight blocks.
Most bowling balls today have differential Rg values in the .040” to .060” range. The maximum differential Rg value is now .060”, according to USBC specifications. These high differential Rg values create a dynamic imbalance within the bowling ball. When a ball is drilled to maximize this imbalance, this causes track flare and results in the bowling ball rotating on a fresh part of the cover every revolution. This erases oil off of the lane every revolution, causing oil pattern depletion throughout the entire length of the oil pattern, instead of only the heads as when bowling balls were more dynamically balanced.
Kegel performs many tournaments every year and one of the things we are constantly measuring is oil pattern depletion. We do this because the main goal for the laneman in tournaments is to try and create a playing condition that has the best opportunity for fair play; in other words, give as many styles a chance as possible. If massive oil pattern change continues to make this task difficult, we need to find ways to help Lanemen do their job better.
How much oil is erased with today’s balls?
During a recent seminar tour, we got a group of bowlers’ together and measured oil depletion after 10 minutes of practice, and then every three games of play. At the end of this test, we had 9 games per lane. To put it in comparison, a 5 person team bowling a 3 game league has 15 games per lane.
To follow are the results of that test:
The greatest amount of depletion occurs during the early stages of play because the ball creates a larger footprint within the oil pattern. In the head area, there were 80 units of oil before bowling. After 9 games, there were about 35 units in that same head area. The move left by the players was not the lack of head oil; it was the ‘spark point’ being reached in the mid lane and the back part of the pattern causing the ball to hook more and forcing the players left.
Now we show why this massive depletion of the oil pattern can affect fair play. The following graphics are a comparison on how different styles of players break down oil patterns.
The event was the 2009 European Bowling Tour Masters featuring the top 16 players, men and women, from the 2008 European Bowling Tour point list. Both groups had 3 bowlers per pair and they played 8 games. So the lanes had 12 games per lane plus 10 minutes of practice on them. There was also an equal amount of lefties and righties on both the men’s side and the women’s side, and every player bowled on each pair of lanes twice within the block, so it was a very good comparison.
The fresh oil pattern was 44’ in length with the same pattern used for both the men and women. Below is the graphic of that pattern:
The first depletion example is the women’s side of the event. They were bowling by themselves and as with most lower rev players, because of the decreased motion on the back end, these type players tend to play in the same area on the lane and in a tighter line to the pocket.
As you can see in the above graphic, the women essentially started at the slope of the oil pattern, the rise from the least amount of conditioner to the greatest amount of conditioner, and broke the oil pattern down in a very logical manner. When oil patterns are broken down this way, scoring pace can increase greatly.
The men played on lanes right next to the women players. Here we had players like Jason Belmonte, Osku Palermaa, Dominic Barrett, and several Scandinavian players with fairly high rev rates. Below is the graphic of how the men broke that same fresh oil pattern down.
Because of the great amount of potential hook we have in the game today, and especially with the higher rev players, the slope of the oil pattern is not always followed as it used to be when bowling balls hooked less.
What is interesting, is the area where the bowling balls roll throughout the pattern, both groups depleted the same amount; over 60%. Testing has shown depletion is not significantly greater with higher rev rates, depletion is only more spread out. Towards the end of the pattern where all balls meet, both groups depleted the same amount, over 60%.
Here is the tape data and depletion percentages at comparable distances throughout the above patterns.
Most bowlers still believe “the heads” breakdown the most and therefore affect ball motion the greatest. This was the case with balls that did not flare, but that’s not the case with balls that flare.
When flaring balls are rolled over an oil pattern, the oil pattern is erased near the same amount,percentage wise, from the lay down point to when the ball exits the end of the oil pattern. The most oil is depleted where the footprint is the greatest, but at each distance, the percentage of depletion is essentially the same.
Once the oil pattern is depleted enough for the ball to reach the “spark point” in the mid lane and back part of the pattern, players start moving inside. And they move until the modern practice of lofting the gutter cap comes into play.
If depletion continues to happen at such a rapid rate, lofting could become the modern way to play the game. After all, we have yet to see a ball hook while it is in the air.
