Skytrak distances

[Jon]

I've been a little concerned(ok, a little more than a little concerned) about the distances that I see when using the ST. I'm not huge off the tee but I can get it out there pretty good, averaging maybe 270 yards on softer than average courses and occasionally poke one out there more than 300 yards. I have only had my skytrak for a few weeks and I have been somewhat disappointed by certain aspects of the ST performance and pleased by others. One area that has been a constant source of concern has been distance reported by the ST software. I have been consistently seeing carry distances in the 225-240 range and total distances from 240-260 range with only a few drives beyond 260. Right off the bat, my thinking was that this thing was 30 yards off on drives. Then I got to think about environmental aspects of distance. I use my ST in an attic (the only spot I have access to without 7 foot ceilings). If I'm hitting balls at a good pace, I might feel warm enough to take my sweater off. But even though I have a small space heater up there with me, the reality is that the temp doesn't climb above the low 40s in that space at this time of year. Cold golf balls are not happy golf balls. I googled how distance affects ball flight and found a variety of discussions that made all sorts of claims about distance loss as a result of cold air. I did find a chart that was copied and pasted from the pga manual of golf into a golf forum. To me, this chart explains a lot about the concerns that I have had about the numbers that I'm seeing out of the skytrak. Only spring weather can unveil the truth but I was encouraged when I saw these changes in distance at different temps.

[Clevited]

Jon,

There are many Skytrak early adopters on here that have seen these types of concerns come up over and over again and the causes explained. I don't mind being the echoer of these truths as I asked many of the same types of questions when i first got mine a year ago. Here are some things to know about your Skytrak and about hitting indoors and even in the cold.

1) Our bodies just don't fire as fast in the cold. Can be due to extra clothes, or just from our muscles being colder but low temps definitely effects performance.

2) Cold temps definitely make a difference with golf balls. It can be a loss of a few mph in ball speed, and even changes in spin. The durability of the ball goes down as well. I keep the golf balls in my pocket and rotate them out every couple of hits to help with this. This could be a portion of the problem you are seeing.

3) Cold temps "could" effect the Skytrak. It even says it somewhere in their product information. It doesn't say how or to what extent, and I haven't been able to for sure see an issue but its something to keep in mind.

4) Indoor swing. This is a big deal. Only way to know for sure is to compare ball speeds on good strikes to when you hit outdoors and to when you hit indoors. For instance, on Trackman i can tag some and achieve ball speeds in the mid 180s hitting outdoors, but in my confined bay, I rarely get higher than 175. A portion of that descrepancy is likely indoor swing.

5) Skytrak does seem to more often then not, under report carry distance with longer clubs. Its not usually a ton, and I feel it does depend on ball speed and spin numbers quite a bit, but regardless, its better than over reporting most of the time.

6) Over estimating our abilities. Skytrak is a humbling machine. It shows us where we are really at. On the course there is roll, elevation change, wind, humidity and temperature that can all add to our club distances. Hitting indoors in a static environment really makes that clear and shows us what we really hit it.

There are other little things like direct sunlight, and too much white on shoes, clubs and the tees we hit off, but those aren't the most common offenders I think. I suggest you keep practicing, then take it to the range when spring comes and see if Skytrak is jiving with what you see. I think you could be very surprised what you find out.

Edit: I forgot to mention that the chart you show is likely including effects of air density on carry distance. This does not apply to Skytrak measurements. Only a physically cold golf ball can cause a change in this instance which I noted in point number 2.

[skytrakali]

I agree completely with Clevited. Indoor Swing is likely to be a factor, as well as cold bodies and coefficient of restitution of balls. On other threads I have given references in the literature to CoR as a function of temperature - this makes a definite difference (but not a vast one).

On longer shots it's much harder to "know" one's normal carry. For a pitching wedge on the course I will often know that the target is (say) 115 yds away and I can get a good idea of my carry by seeing where the ball pitches. I can use my GPS to measure the distance to the pitchmark. So I know that ST gives me the correct distances for the shorter clubs. But it's much less clear with my driver and much harder for me to know my normal carry. One round this June on the course I hit a driver 289 yards (note: I'm 60 and I play off 18 and my knee hurts - I'm no DJ) but I have little clue what the carry was. It could only have been 210 - but a hard fairway, a good bounce and an optimal roll got me out to 289.

One other thing: ST doesn't really know what club you are using. (OK you can tell it but I don't think that this really affects the ball flight algorithm). It just solves some equations using spin, ball speed and launch conditions. So there's no reason for it to be wrong. These equations are really very accurate and robust for ball flight. So despite having some initial concerns I am now very confident in the ST results that I get. BTW, in the UK we have quite a few ranges now with ProTracer (e.g. Silvermere in Surrey) and that makes it possible to compare ST and ProTracer for range hits. They are always close.

[Mirek_62]

You say you average 270 yards. Is it total or carry distance?

As has been said many times, it is impossible to compare the total distance achieved outside and inside.
No simulator can calculate exactly the run of the ball. That is why you MUST ALWAYS compare CARRY distance.

For good golf, you need to know your carry distance for each club.
Only consistency in carrying distance will bring significant improvement in golf.

[Jon]

Most people say that ST is short, at least on the driver. How many yards would you estimate the ST is short. As a training aid, it’s not such a big deal, but when it comes to sim play, it makes a big difference.

[Clevited]

For your numbers it could be 5-10 yards short, but it sometimes is a little long. It is however incredibly hard to decypher how different they are as there is no one number it can be short by. It depends on ball speed and spin, and spin axis. High spin, ST can be off nearer to 10 yards but this is when compared to flightscope trajectory optimizer. You have to get on Trackman along with your ST to know for sure. I have done that and my ST differs in ball speed by up to 8 mph which is the majority of my difference. I have however, higher than typical ball speed and I feel ST accuracy diminishes the faster the ball speed. I do however have screen shots showing 8 yards less carry compared to trajectory optimizer and 8 yards more carry compared to trajectory optimizer. If you want to see those, i can direct you to the thread i posted them in.

Essentially, I feel strongly from experience, ST more often than not is a little short on carry. It isn't a ton, and can be hard to pin point an actual amount as it depends on things. It can be different unit to unit, swing to swing. I suggest finding your nearest golf club that has a Trackman and do your own private head to head and record the differences you see.

I have been talking about driver, but this also pertains to irons. I have screen shots of pitching wedges that carry 155 or so, when I know, without a doubt, the launch numbers get me closer to 165 irl. Trajectory optimizer backs that up, as does my personal experience GPSing many shots. These are however spinning near 11k rpm, and launching with most peoples 7 iron ball speed so I think for most people, it won't be off by that much, more like 5 yards max.

[Morini]

There is a YouTube with a fellow who did a side by side with skytrak and gc2. He set up the GC as a lefty so he can measure the same shot. It was very similar, but for the longer clubs, the st was a bit low on carry. The ball speed was slower, so I think the issue is in the measurement end rather than the ball flight model. I will have to watch it again, but it was consistently 2 to 3 mph, so about five yards, sometimes quite a bit more.

[Clevited]

https://youtu.be/z5bifppIjq4

Is this the one?

[Morini]

Yes, that is the one.

[Rectur1942]

thanks people very much for all your answers and thanks a lot for the youtube video. i appreciate it very much!

[N54TT]

I’ve taken my skytrak to the range and it’s pretty spot on....both in distance and shot shape. happen to hit on a trackman for the first time and took my skytrak to compare. Considering the price I paid for the skytrak....I’m still pretty damn impressed.

[Clevited]

I guess it depends on your unit, and your ball flight characteristics. I think if given the opportunity, everyone should go test it against a Trackman.

A pretty extensive review was done here http://www.golfwrx.com/450552/review...aunch-monitor/

This person got data more in line with what I typically see. In the article the reviewer tests against a Trackman. Below is the data from his tests.

[Jon]

I'm hopeful that in the future, updates to the ball flight algorithm will close the gap in disparity between the ball speeds measured by the ST and trackman

[N54TT]

I'm hopeful that in the future, updates to the ball flight algorithm will close the gap in disparity between the ball speeds measured by the ST and trackman

Algorithms only impact calculated data like distance etc....ball speed is a direct measurement. So unless Skytrak improves the cameras, resolution and how many pictures are being taking....there will be no change in measured ball speed. But IMO not even taking the huge price difference into consideration. The Skytrak has already shown that it can be very close to Trackman.

[Jon]

I agree completely. What I meant to say was that I hope Skytrak will be able to interpret the ball flight data more accurately in the future(mostly in regard to ball speed, particularly with the longer clubs). Whatever is needed to make that happen. The numbers stated in that article comparing the ST with trackman weren't that far off. As a whole, however, the article read like an incognito advertisement for ST. The data posted in the article may or may not have been cherry picked. The side by side comparison data would have been a lot more compelling if it included a link to video recording the actual testing and not just a spread sheet that displays results. However the numbers displayed in that spreadsheet do seem to ring true for the most part.
-Assuming the data gathered is legit: (I have a feeling the difference between trackman and ST is a bit more substantial) A 10 yard difference in carry distance on a driver is large enough that it gives a significant advantage to the trackman user when competing in a sim based tournament.

[Clevited]

Jon,

I personally own a Skytrak and I have no problem backing up the numbers I have seen in any video or review. There are indeed times where Skytrak will differ from Trackman, or Flightscope or Gc2/Quad,but it definitely holds its own.

I have tested it against my local Trackman a few times and I know at higher ball speeds it starts to deviate ball speed wise. That is completely hardware related I believe. Faster the ball, the more blur in the image it takes, the more possibility for error (I am guessing this is how it works). I assure you Skytrak is a very very good device for the money. It is accurate and repeatable enough to be able to test the difference between balls and clubs.

You also have to remember that every device is going to have error. Often, Trackman is COMPLETELY wrong with certain perameters. Its best ability is tracking ball carry, and ball speed. There are inherent flaws with this though as weather can make a huge difference. Often weather is not accounted for with the Trackman and that can ruin a comparison. The arricle I posted and Skytraks own numbers are completely believable. The reviewer in the article tried his best to account for weather even, to make the best possible comparison. I see differences very similar to his in ball speed and carry, but others have tested and see no appreciabke difference. The largest difference one usually sees is caused by our own inconsistent abilities. We are not robots.

I truly recommend you find a Trackman, make sure you capture shots simultaneously, turn normalization on, on the Trackman and hit away. I think you will come out vwry satisfied with the Skytrak but perhaps disappointed in your own abilities. That is usually how it goes.

[jut111]

Well said. people compare stuff to trackman forgetting that even track man has a + - tolerance on measuring data. It is not infallible.

[Clevited]

Just to make or reiterate a few more points.

1) Skytrak is rarely considered too long with its representations of our shots, usually it is right on or a tad short. Most on here find it very close, some find it a tad short (like me). It does seem to be consistent that it reads slower ball speeds at high ball speeds, im talking 160 mph +. It can deviate some at lower speeds as well as shown by the review.

2) Most often, the reason for major descrepancies is player incorrect perception of their abilities and swinging indoors. Those are proven facts and it plays like a broken record on these forums, over and over again. You also need to remember that hitting off a mat can make a large difference in launch characteristics of a ball vs hitting off the ground. There are a lot of variables that can make a person perceive that Skytrak is overly inaccurate.

3) Yes there could be a small disadvantage with Skytrak's tendency to be a tad short. It depends on your unit, depends on your launch conditions. Yes, some tweaking to their ball flight model could be done (namely fixing spin decay or lack thereof) but they can't add some flat percentage of ball speed because its a hardware limitation and it isn't a consistent number of mph off. It differs shot to shot, and really is only a problem like I said, at high ball speeds which most peoplw don't have.

4) Again, only way to know if YOUR particular Skytrak has less or more deviation from what is real, is to go head to head with a Trackman and make sure it is on normalize mode if hitting outdoors.

I might spew some more later on this forum to clear this issue up, but for now, phone needs to charge.

[JiggaFresh]

The indoor swing is the most difficult for me. Wedges are perfect distance, everything from 30 to about 115 is absolutely spot on with what I see on the course. When I get into the PW through the 8 iron, I see a little bit of decay. My 5, 6, and 7 irons can be anywhere from 20 to 40 yards short. Can't make much of a comment on the driver, it's tough to clear your mind and swing free.

I'm really hoping I can either figure out the setup or get over the inside swing. It pretty much renders JNPG useless since I'm hitting shots that are no where near what I would see out on the course.

[Clevited]

Driver is super tough even after a year for me. I have a pretty large bay, but a car right next to my hitting area. One really bad hit is all it will take for me to dent it or brake a window. My netting is also wearing out, I have several holes through my net, and two layers of mesh tarp. Some dings in my garage door show the result of that. All of this keeps me from feeling comfortable swinging the driver. I really get to see just how much I hold back when I occaisionally use the Trackman at a nearby golf course. Its significant!