Zero Off

[G-man]

I had an early edition PP and the pitot was only used for Trick mode. It had the rpm sensor for slalom mode. There was no wakeboard mode because who cared then.

[Laketexoma]

Yeah G-Man like you care about us wakeboarders!!! Yellow_Flash_Colorz:

[NCH2oSki]

PP speed is based on engine rpm, not from a speedo pitot tube. You have to set the rpm values making passes thru a slalom course with magnets to be the most acurate. Then you set the rpm for each speed, it takes a while but it is pretty accurate.

This is true now, but in the early days of PerfectPass, it was pitot based. It was a much different pull at that time and took a lot to get used to.
Dave

That is interesting, I didnt know it ever used the pitot. I guess that was version 1.0? How long ago was that?

[skiinxs]

Hard to remember, but I think it was around '95.
Dave

[ClemsonDave]

Continued from another thread....

Ok, so how did those times show up then? How does ZO measure times? I thought all ZO did was to set up the gas such that the boat went the speed that was asked for. Times have to come from something else...

OP- sorry for the continued thread jack, it really is a good lookin boat and I'm sure you'll have a lot of fun.

As I understand it, when visiting a new site, you place the boat at each gate and mark that point. The computer then calculates where the other buoys should be. Then you drive it as normal. When the boat gets close to speed, it locks the SPEED in. As it passes the gate, it activates a timer. It ends the timer at the exit gate.

One cool feature that I have heard but not seen is that it will automatically know which site you are at (assuming you have previously marked the gates) based on GPS position. So, you dont have to recalibrate everytime you visit a lake you have already been to.

[tomdarcy]

For free skiing, speed over the water may be the important factor and in that case I would think the speed based PP would be your best option. Our club has a slalom course in an environment where there is both wind and current on occasion. In theory, the GPS based system would turn driving into even more of a no brainer. I'm looking forward to checking it out!

By the way, I wonder how many marriages were saved by PerfectPass...

[skisix@38]

Continued from another thread....

Ok, so how did those times show up then? How does ZO measure times? I thought all ZO did was to set up the gas such that the boat went the speed that was asked for. Times have to come from something else...

OP- sorry for the continued thread jack, it really is a good lookin boat and I'm sure you'll have a lot of fun.

As I understand it, when visiting a new site, you place the boat at each gate and mark that point. The computer then calculates where the other buoys should be. Then you drive it as normal. When the boat gets close to speed, it locks the SPEED in. As it passes the gate, it activates a timer. It ends the timer at the exit gate.

thanks for the response. that's some of the best info I've heard yet. My question now is that I get my boat and go over to the start gate and get close and click a button... then I go to the end gate and get close and click a button- how do I know if I was close enough when I clicked setting the way points? We got rid of hand timing a long time ago because we knew the error of that method now we are basing our GPS system on the same error?

I'm not dissin you CD, just asking questions here because I'm not getting answers anywhere else. I appreciate your efforts to explain.

One cool feature that I have heard but not seen is that it will automatically know which site you are at (assuming you have previously marked the gates) based on GPS position. So, you dont have to recalibrate everytime you visit a lake you have already been to.

[ClemsonDave]

Everyone still has much to learn about the system. I have not calibrated it myself yet. I have skied several sets and driven several sets. I do not have a specific answer to your question, but I will ask those that have done it. They told me that it is quite easy, but didnt go into details. My GUESS is that you pick a spot on the hull and put that next to the entry gate buoy. Use the same spot on the hull for the exit gate buoy.

I think the biggest adjustment we need to make is that the TIMES do not matter. It is all about the SPEED. Times were mearly a measurement to get accurate speed. This thing goes directly to the source and gets accurate speed. I forsee when we dont even record the times anymore. Yes, it is that accurate and no, I am not affiliated with ZO. Of course, it will take time for it to prove itself.

I was a skeptic until I heard of the results from the Trophy Lakes tournament with 40mph winds and seeing it myself at a local site. I will tell you that I enjoyed driving and skiing it so much that I am selling my '03 196 and joining the promo team. I expect to have an '08 with ZO in December.

[SGY]

skisix, I read some place that setting the way points at or around the exit gates is not and does not have to be an exact science. I'll see if I can find it.

[east tx skier]

Continued from another thread....

Ok, so how did those times show up then? How does ZO measure times? I thought all ZO did was to set up the gas such that the boat went the speed that was asked for. Times have to come from something else...

OP- sorry for the continued thread jack, it really is a good lookin boat and I'm sure you'll have a lot of fun.

As I understand it, when visiting a new site, you place the boat at each gate and mark that point. The computer then calculates where the other buoys should be. Then you drive it as normal. When the boat gets close to speed, it locks the SPEED in. As it passes the gate, it activates a timer. It ends the timer at the exit gate.

One cool feature that I have heard but not seen is that it will automatically know which site you are at (assuming you have previously marked the gates) based on GPS position. So, you dont have to recalibrate everytime you visit a lake you have already been to.

For 2008, Zero Off is required to separately record times as indicated by an alternative backup magnetic timing system. I'm not sure if that is just to double check it due to its experimental status or what, but it seems that the AWSA isn't rock solid on using GPS coordinates as the sole timing system yet.

Here is the AWSA 2008 Blanket Exception for using Zero Off in record tournaments.

http://www.usawaterski.org/default.asp?Display=51

For free skiing, speed over the water may be the important factor and in that case I would think the speed based PP would be your best option. Our club has a slalom course in an environment where there is both wind and current on occasion. In theory, the GPS based system would turn driving into even more of a no brainer. I'm looking forward to checking it out!

At one point, PP recommended speed mode for free skiing. I tried it on v 6.4 and found the speed input to be a little too sensitive to skier pull. In other words, it was overcorrecting for skier pull and speed was inconsistent. I've found rpm mode to be better for free skiing. In 6.5 ng, you can set up a memory for free skiing and just add rpms to compensate for the 28% rpm ramp up of skier weight at the one ball. Since there's not timer trigger when free skiing, it might feel a tad slow otherwise.

[ClemsonDave]

For 2008, Zero Off is required to separately record times as indicated by an alternative backup magnetic timing system. I'm not sure if that is just to double check it due to its experimental status or what, but it seems that the AWSA isn't rock solid on using GPS coordinates as the sole timing system yet.

Here is the AWSA 2008 Blanket Exception for using Zero Off in record tournaments.

http://www.usawaterski.org/default.asp?Display=51

My understanding of the exemption...

there are two reasons that I have heard for using the secondary.

1. Just like you said, to double check that the ZO system is pulling good times. There have been many tournaments pulled with ZO now, so I'm sure they are computing all the data.

2. All of the current rules for AWSA revolve around TIMES from buoy to buoy (fixed points). Since ZO calculates theoretical all buoy timing, it does not meet the CURRENT rules. I expect that to change the next time the rules committee gets together. Again, see my previous post on TIME versus SPEED.

I am certainly hoping that the rule gets changed before next year. I dont really want to have to pay for both PP and ZO in my promo.

[east tx skier]

My understanding of the exemption...

there are two reasons that I have heard for using the secondary.

1. Just like you said, to double check that the ZO system is pulling good times. There have been many tournaments pulled with ZO now, so I'm sure they are computing all the data.

2. All of the current rules for AWSA revolve around TIMES from buoy to buoy (fixed points). Since ZO calculates theoretical all buoy timing, it does not meet the CURRENT rules. I expect that to change the next time the rules committee gets together. Again, see my previous post on TIME versus SPEED.

I am certainly hoping that the rule gets changed before next year. I dont really want to have to pay for both PP and ZO in my promo.

Thanks, Dave. I'll reread the post you mentioned. My understanding is that PP will have an rpm based system with GPS input soon that I believe is an upgrade to their present system and will work on both TBW and older wired throttle boats. I think the competition from Zero Off is having the nice side effect of accellerated R&D on their part. I have not used Zero Off yet, but hope to soon.

All that said, I'm still a loyal Perfect Pass customer. I am a huge fan of their customer service.

/edit. Regarding time versus speed, as I understand your point (and as I understand the system), the waypoints in ZO are for timing, and the engine ECM monitors speed based on a signal from the GPS and adjsts to maintain speed without regard to timing.

For purposes of the rules, assuming the waypoints are accurate enough, instead of using theoretical all ball timing, couldn't waypoints for each ball could be added in addition to end gates?

[ClemsonDave]

I'm sure the waypoints could be added, but why? I had the same questions you do, until I spent more time with it. Buoys are not important to speed. IF you accept that ZO will always pull a skier at 34.2, then why does time matter? Yes, it needs to be proven that it works, but after that, why does time matter? It will be a big leap for skiers to accept, but I think it will head that way.

Think about it this way, non skiing related... Do you accept that a 1' is always 1'? Or do you always measure that 1' with 12.00"? You probably have faith that a foot is a foot and don't bother to measure it with inches.

Now, if the rules committee comes back and says that over 1,000 passes were pulled with ZO under various conditions and skiers and EVERY pass was within 0.03 seconds. Would you accept that it is accurate and times will eventually be irrelevent?

Interesting about PP and GPS, I heard that they were working on a system that only uses the paddle wheel, not RPM or GPS. Who knows... :grin:

edit: one more thing... I seam to remember that GPS position (at least the non military version) is not accurate down to inches. However, speed IS accurate.

[skisix@38]

Everyone still has much to learn about the system. I have not calibrated it myself yet. I have skied several sets and driven several sets. I do not have a specific answer to your question, but I will ask those that have done it. They told me that it is quite easy, but didnt go into details. My GUESS is that you pick a spot on the hull and put that next to the entry gate buoy. Use the same spot on the hull for the exit gate buoy.

I think the biggest adjustment we need to make is that the TIMES do not matter. It is all about the SPEED. Times were mearly a measurement to get accurate speed. This thing goes directly to the source and gets accurate speed. I forsee when we dont even record the times anymore. Yes, it is that accurate and no, I am not affiliated with ZO. Of course, it will take time for it to prove itself.

I was a skeptic until I heard of the results from the Trophy Lakes tournament with 40mph winds and seeing it myself at a local site. I will tell you that I enjoyed driving and skiing it so much that I am selling my '03 196 and joining the promo team. I expect to have an '08 with ZO in December.

Thanks again Dave.

Speed is the derivative of time and distance. So, for a given distance time is the only true way to derive the average speed through that distance- I don't believe we'll ever get away from time. I don't agree with your argument, there is no conclusive measurement for speed, the only conclusive measurement we can make is a time through a known distance.

Even using the same spot on the hull you could be +/- 4" overall and that's not taking into aaccount that the course requirements are +/- a few inches too. I don't know if that makes a difference but it could put things into question.

[east tx skier]

I'm sure the waypoints could be added, but why? I had the same questions you do, until I spent more time with it. Buoys are not important to speed. IF you accept that ZO will always pull a skier at 34.2, then why does time matter? Yes, it needs to be proven that it works, but after that, why does time matter? It will be a big leap for skiers to accept, but I think it will head that way.

Think about it this way, non skiing related... Do you accept that a 1' is always 1'? Or do you always measure that 1' with 12.00"? You probably have faith that a foot is a foot and don't bother to measure it with inches.

Now, if the rules committee comes back and says that over 1,000 passes were pulled with ZO under various conditions and skiers and EVERY pass was within 0.03 seconds. Would you accept that it is accurate and times will eventually be irrelevent?

Interesting about PP and GPS, I heard that they were working on a system that only uses the paddle wheel, not RPM or GPS. Who knows... :grin:

edit: one more thing... I seam to remember that GPS position (at least the non military version) is not accurate down to inches. However, speed IS accurate.

Checks and balances. That's all it is. From my brief time in the cockpit, I was instructed to not trust my gauges. If the fuel gauge said full, we still got a stick an stuck it in the tank on the wing to see how much was wet. If someone tells me something is a foot, I measure twice.

I think the "error" was removed from GPS recently, which is good for these purposes. But when GPS gives you speed, like Greg said, I think it's still just doing very fast calculations of distance over time. So unless I'm sure of the accuracy and degree of error in the GPS signal and how it's read by the receiver (as I can't imagine even with WAAS that we've got military grade accuracy in Zero Off), I'd support the checks we can get from a timing system.

Of course, even when we have cars that will steer themselves, I'll still have one hand hovering above the steering wheel and the other on the override button. :grin:

Now I'm just a hack. I get into the course, but am neither a tournament driver, nor a tournament skier. I am interested in the system though as well as what PP's take on a GPS system would be. I'd heard paddle wheel initially, too. But last rumor twice removed was RPM. Time will tell, of course.