HWIs

Before reading on I would like to say, for some people, figuring out these numbers is half the fun. So if you would like to do the work yourself, do not read the HWI-page. No-one is stopping you from doing it yourself. In fact, I will just applaud you for it.

So here are the infamous HWIs. Let me just say if you come here to just download these numbers and use some different method to calculate and it does not work and you end up complaining, then I will just laugh at you ;>
Also, do not be scared away by this list. It is really simple to use.

Here is the list of HWIs as image with an explanation of all the terms below, you can download it as table in Excel and OpenOffice format here!!! (download at your own risk!)

(Click image for enlarged view)

So we see three sets of columns here. The first set is for Tomahawk, the second for Backspin and the third of elevation adjustments. I will only explain one of the first two since they are the same.

Starting from left:

Pin

(Pin = Hole by the way)

NB!!! PLEASE NOTE, PIN DISTANCE IS NOT EQUAL TO THE DISTANCE YOU NEED TO HIT THE BALL TO GET TO THE HOLE BECAUSE ELEVATION IS IGNORED IN HWI SELECTION. GETTING YOUR FINAL POWER IS PIN DISTANCE +/- WIND +/- BALL EFFECT +/- ELEVATION !!!

The method of calculating I use here is called “pin method” (There are other methods with the same or very similar formula, but I am not very practiced in them, so no point in trying to explain them). This means, we take the HWI that represents that pin. NB: Only WIND and BALL EFFECT (98%, 95%, 90%, etc) will change the pin distance. When doing your shot, there will be distance to the hole displayed on your screen. For example:

The pin is 240yards away, the elevation 0, Ball effect is 0 (meaning 100%) and you have a cross wind (meaning the pin distance will not change, more about that later in thorough examples) and you want to TOMAHAWK.
You do this: take the list, look at the “pin column” and go to 240. In HWI columns (third column that is!) you will see the HWI for that pin which is 3.34 Powerbars in this example (explanation of powerbars just below). Take it and put it into the formula. Easy, no? Obviously we have not calculated anything yet…

Power

Pretty self-explanatory. The Power tells you how far the shot will go. This is not 100% correct if you have paid attention. Because the maximum for 250y drive Tomahawk with no wind effects is 264.7yards. This list is just a reference for you. They are not 100% accurate values. You can see some values that are higher than 100% club power. This is because the method we use here takes the HWI for the Pin distance. We will sometimes get pins that are 270yards away for example, but circumstances such as negative elevation and tail will allow us to reach the hole anyway even though the maximum for 250y drive tomahawk is only 264.7y. The same goes for pins that are lower than the actual minimum. E.g. 195 pin with +8m elevation. 195y is not in your power range, but with +8m Elevation it is.

Moving on. What is an HWI?

HWI

As mentioned before, HWI stands for Horizontal Wind Influence. It is the Horizontal (90 degree angle) effect on the ball in 1m Wind. For our example above, the HWI was 3.34 Powerbars. Now lets say the wind is 6m at a 90 degree angle. The HWI will still be 3.34 Powebars, but as a result if we were to calculate it out, it would be 6 TIMES 3.34 Powerbars (because the Sin of 90 is 1, so 1x 6 x 3.34 Powerbars) which is 20.04 Powerbars or just 20.0 Powerbars (we refer to Powerbars as “PB”).
How do we see powerbars on the screen? Like this:

(Click image for enlarged view)

50% of your the entire bar is considered 0, so when aiming your shot you centre the the 50% line on the hole, but more about that later. Each 10% step to the left/right is 1 Powerbar. So the maximum you can move at once using the bar is 5 to each side (Well, as you can see, 6 to the left, but I do not use that). You do this by hovering with the bottom part of your mouse cursor over the bar selecting a distance and the tip of the cursor on the green. If you then click, it will move the selected distance. How this is done can be seen in pretty much any video on the Video’s page.

Slope

I am only going to explain how to use the slope numbers here and not go into too much detail. When we do not get a flat ball slope, we can see line breaks on the ball. Depending on the distance we multiply the number of lines with the Slope modifier. As mentioned in the Formula section already, it looks liked this:
(Number of Breaks x Slope modifier x HWI)

Taking the example of 240y again. Lets say we have 2 breaks, then it looks like this:

(2 x 0.25 x 3.34) which is PLUS or MINUS 1.67pb to your aim, depending whether the slope is leaning with or against the wind. The slope modifier increases as the distance increase. Actual calculation examples with slopes can be found here.

Elevation Mutliplier

NB !!!!MOST IMPORTANTLY, THOSE NUMBERS ARE ONLY FOR POSITIVE (MEANING +X meters) ELEVATION ONLY. NEGATIVE ELEVATION FOLLOWS A DIFFERENT RULESET WHICH IS NOT COVERED IN THIS GUIDE!!!

As tonycheese explained in his guide. Elevation effects the distance of your ball. If you have a high elevation at a very low distance. For example:

Pin distance: 210yard. 0 Ball effect. 0 Wind effect. +6meter elevation. You have to hit the ball harder than just 210+6. This is where the elevation multiplier comes in. For this example: Distance 210yards. Go to the list. Look at the elevation multiplier for 210 yards, which is 1.58.
So you do:

6meters x 1.58 = ~9.5.

So the real distance you need to hit the ball to reach the whole is 210yards +9.5, or just 220y. You don’t have to be that fussy about the decimals. The list is just there to indicate that the modifier changes depending on distance. After a while you will just know how many yards to add to your power without having to look in the list and without calculating it every time. This is also NOT perfect. It’s just to give you an Idea. Some holes work different with +20m or something. The multiplier may not work here!

Elevation Modifier/Adjustment

From my experience, these Elevation Modifications work for all drives. I play 260y on Korea right now, and this works.

The last set of columns is the needed modification for your HWI depending on elevation. tonycheese and I already explained that if you have a negative elevation at a certain distance, the ball drops -> more wind effect on ball. Vice versa for negative elevation. Lets take the 240y example again:

Three scenarios with the same conditions except for elevation: 0 Ball effect, crosswind, no slope. So we have:

1)240y with 0 elevation
2)240y with -5m elevation
3)240y with +5m elevation

1) There is no elevation effect, so the HWI will still be 3.34

2) The ball drops 5 meters -> bigger effect on ball -> HWI has to be adjusted (increased in this case). Go to the list, look where you see 5m in the “Elevation” column and add the corresponding value from the “Adjustment” column. This is 0.07 in this case. Therefore we have:
3.34 + 0.07 = 3.41
This is your hwi for the shot now.

3) Opposite case here. +5meters -> less effect -> decrease HWI. Resulting in:
3.34 – 0.07 = 3.27

Now that you have gone through all this, head back to the Examples page to go through some calculations.

Things to remember:
– HWI Selection is: Pin distance +/- Wind effects +/- Ball Effects (95%, 90% etc)
– Adjust HWI for elevation
– To calculate slope use the HWI after Elevation Adjustment
– Positive and Negative elevation follow different elevation rules
– Final power is: Pin distance +/- Wind effects +/- Ball Effects +/- Elevation
– The elevation multiplier is not perfect. Some holes may require manual adjustments