HP, torque, geeks, PP and ZO, Nate and Bob

[gator1]

Been thinking about this for awhile, and the questions on 5.7 vs 6.2 needed to pull the big guys triggered the geeky again: When I was testing speed control back in the 80's, I had an o'scope on my electro speedo, recording the actual, no-lag reported speed (airguides had over a 0.5 second lag) as the top drivers in the world hand drove guys on the pro tour.

 

The monsters, like BL, experienced much larger variations in speed than the smaller guys. They all got good times, but the heavier you were, the more the drag down and overshoot.

 

In essence, the big guys were skiing "PP", while the small, lighter guys were skiing first generation ZO.

 

Two causes: hand driving was limited to "no gassing" because the response time of humans and airguide made it impractical, AND, the engines just didn't have the torque to hold speed.

 

Another interesting point (well, to me anyway) was that the big jumpers weren't getting 35 mph from the turn to the wakes. No matter how hard the driver hammered the throttle, they drug the boat down to below 33 in the most extreme cases, while Sammy and Geoff were seeing close to 35.

 

So, I think ZO and 350 hp + motors enabled Nate's dominance, and made it possible for Regina to whup most of the big dogs.

 

And this is to take nothing away from BL and any of the other stars of the past, they were studs of no small order. But, I think its interesting that tech MAY have altered the prototypical body type required to dominate the sport.

[A_B]

So adding weight over the last 5 years was the wrong direction? Now you tell me...

[gator1]

@AB; Um, I saw your snow ski pics. I'm pretty sure you missed the prototypical body type of both the hand drive and ZO era. But, good news! Now that you know you were just confused on the ideal, you can winnow yourself down to a Nateish degree of svelteness and watch your scores skyrocket.

[andjules]

Fascinating measurements/observations.

 

Maybe an ignorant question, but if

its interesting that tech MAY have altered the prototypical body type required to dominate the sport

is it also possible that it just levelled the playing field? Are heavy hitters really at a disadvantage or have they just lost their older 'weight vs boat' advantage? It's not like a Chris Parrish can't compete, right?

[gator1]

@andjules: Yep, that was what I was trying to say: My theory is that you are no longer required to be NFL linebacker to be a worldbeater slalom dude or dudette.

 

Doesn't mean you CAN'T be a worldbeater if you are a NFL linebacker.

 

I'm not prepared to say those of slender build are now at an advantage. But I think strength to weight ratio, at a given level of skill, is now the main predictor.

[ozski]

I would give Nate the edge in terms of power to weight ratio over CP. Another interesting point is that when you speak to a jumper that is on the lean side they feel ZO is not as good as PP because of the difference in the switch.

[Razorskier1]

While I wouldn't have said it the first year ZO was in boats, I do now believe that ZO will help any skier who takes the time to understand the system and what it does. What ZO doesn't do is let you just hammer on it and hope to get through the course (like I could do on PP or SG). However, if I understand that ZO will help me if I ski better, then its all good!

[Ed_Johnson]

I believe Revision R has really helped the 200 lb plus Guys...I know for me, at 6'4" @225, the Plus has been a life saver...I am enjoying skiing much more and ZEROING in on the shorter line lengths I was able to muscle through on PP.

[ntx]

@ozski A lean jumper who knows how to set up ZO does not have a problem with it or prefer PP. The problem is that too many skiers don't understand ZO for jump and try to apply the PP thinking. It does not work. First thing that most need to do is REDUCE the letter. Unfortunatly, many drivers, even at class L and R also don't understand the system. Not many drivers have the chance of driving practice for someone going over 180 feet. Just like slalom driving, practice make perfect. OK go ahead and flag it off topic. LOL fyi ZO still has a switch for jump. Same as PP

[ozski]

@ntx - This was feedback I got from a 60m jumper I was skiing with yesterday, his point was that heavy jumpers have an edge over him with ZO.

[ntx]

@ozski Sorry but I disagree. Nick Lang and Taylor Garcia both go 55 plus meters at 51KPH and are most likely under 68 kg. It is all in how you work the system and how you set it up.

WOW look at us. Talking about jump on BOS. Taylor has been close to 60 m (59.4) but at 54 kph. A pretty good poke.

[ntx]

@OB That's cold.

[Horton]

@ozski if you said stronger jumpers maybe. I understand the idea. The more you pull the boat down the more it rebounds but the more speed you can build with less effort the better.

 

Heck I don't know. I quit jumping before Perfect Pass or big skis. I am a dinosaur in jump circles.

[ozski]

We started off talking PP - ZO slalom and it was just his point of view, for the same reason heavy slalom skiers can get smacked by ZO strong or heavy jumpers have an edge because they can induce a stronger reply out of ZO over a lighter skier. Seemed to make sense to me.

[Bruce_Butterfield]

@gator1, generally good observations, but I’m going to quibble with a few points.

 

Hand driving was limited by the slow response of the carbureted engines more than human response and airguide. Once the fuel injected engines hit, circa 1994, the good drivers would feel the pull and be able to respond in pretty good sync with the skier.

 

The technology definitely did alter the prototypical body type, but its due to the myopic goal of the speed control to keep “constant” speed, but gives a very different pull to different skiers. What happens in any feedback control system is that the control system must experience a change in speed and respond with throttle (acceleration). It’s that acceleration that creates a very different pull for the heavier skiers. So the admirable goal of providing the same pull to every skier fell short and actually created a disadvantage to the stronger/heavier skiers due to the increased throttle response that skier receives.

 

So it’s the big motors AND the ability to quickly apply throttle that makes a disadvantage for the stronger skiers by accelerating the boat while the lighter, smoother skier has an advantage.

 

If we can ever get to the proverbial tug boat - big turbo-diesel with a 48” diameter prop that doesn’t care who’s on the other end of the rope - we may finally get the same pull for BL as for the lightweights – then we will really have the same pull for every skier that we do not have today.

 

For max performance, I’ll take a GOOD hand driver over ZO or PP any time. The frequently overlooked point is the huge benefit that PP and ZO have provided for the 95% of skiers that don’t have a GOOD practice driver, the speed control offers consistent practice. I believe that is probably the single most dominant factor in the performance rise of the “average” skier.

 

[Skihack]

Maybe it may be more fair to do it like boxing and have weigh in. Have weight classes. I have seen weight gain from adolescents trim performances significantly and big time. If you want to ski competitively be ready to pay for a house (boat),and do not eat. It is just that simple. Otherwise, stay off the dock.

[Bruce_Butterfield]

OB, I wish I could blame something else, but as much as I fight it, it just sucks getting old!

 

For me, ZO is a harder pull than PP, which is harder than a good manual driver. The overriding factor is that skiers learn to adapt to change - whether its a new ski, speed control or a new line length - practice it enough and it becomes normal. The biggest thing speed control offers is consistency, which we did not have in the old days.

[gator1]

@bruce_butterfield: Depends how you define "max performance". If you define it as a 36mph pull, +/- 0.10 mph, a good manual driver cannot get close to consistently maintaining that pull.

 

If you want to define "max performance" as "how many buoys can I get around with the boat speeding up and slowing down while averaging 36 mph", then a hand drive will provide it. Just as a dream weave will get you a lot more "max performance" than a straight line pull down the center.

 

I'm pretty clear on how a closed loop feedback system works. With a high enough sampling rate, and sufficient response speed and power, the set point can be maintained to a point that the difference in speed is not perceptible.

 

Hell, my system, in 1986, was close to your diesel tugboat. EVERYBODY hated it. Just taking the airguide lag out of the system, taking the human response time out of the system, and cranking the sampling rate up got me close to a tugboat. But that took about TWO passes off everybody's PB. O'scope traces showed I was damn close to 36 at all times.

 

I quit because I didn't want to fight the battle presented by admitting all scores prior to speed control needed an asterisk.

 

The dirty secret (which drove all the development time invested), is that PP and ZO coupled with a 350 hp motor and FI are perfectly capable of providing your tugboat pull. It'll knock about two passes off yours and everybody else's PB. Ready? Lets do it!

 

So, the industry spent years trying to create a system that will protect our egos with A1+ to C3-, which is actually just letting you induce some error between set point and actual speed at different, consistent points in the pass (instead of where Jack Walker's need to take a piss and a break caused him to miss set point).

 

We've now boiled the frog to the point that the big guys don't have an advantage. We have the tech now to crank the damn thing up, and run everybody at set point. Take all this BS about ZO A+ setting out of the discussion. But we'd all have to face a big decrease in our "max performance". I'm in big favor of doing that, since longer line lengths minimize the effects of dream weaves.

 

But, right now, I'm just a drunk, old, bald engineer, so I'm happy enough to be able to compete with a 6'2" 220 pounder on close to equal terms.

[Dusty]

I can agree the boats probably did not have the necessary torque compared to these days, but most of the good hand drivers of my acquaintance were not really driving off the speedos, except to set up the boats maybe. They did respond too slowly- We used the tachs- and did add throttle to maintain constant rpms under load- sort of an early version of PP Classic ?...

[A_B]

Back when I was somewhat skinny around 200 pounds, and a 38 off threat, and pre-PP, I didn't have a preference between a driver who would bump throttle above speed at gates and let me work it down between buoys or hot sticking the whole way through. PP seemed more like the one bump method, so just helped keep times dialed in. The big difference that I see is that I could lean on either method and end up a tad slow at the end time, as not many drivers would know how much to adjust after a huge pull vs a normal pull, whereas ZO hammers me as hard as I hammer it. The additional 50 pounds from not skiing or working out just exacerbates it.

 

[gator1]

@dusty: Yep, you are exactly right. The best drivers could hold RPM constant (hot stick as @AB calls it) once they determined what rpm they needed to get the airguide centered up, based on that boat load, prop, skier weight, headwind, etc. PP classic was a look-up table driven, high update rate version of the human driver.

 

But at a steady rpm, the big guys pull the boat down more than small guys due to prop slippage under load. And, as @AB says, a sudden change in one of the parameters (him hammering it) made the prop slip more, which threw the drivers fuzzy logic control loop out the window and resulted in a much greater deviation in speed during hammer time.

 

With a no-lag speedometer, his spatial knowledge of when the pull was going to come, and familiarity with the boat and skier, the best driver could hold SPEED almost constant, given a strong engine at sea level and a semi monster or less at the end of the rope. Airguide made a no-lag speedo for awhile (my patent). Anybody who got pulled constant speed hated it. It meant a lot more throttle movement (and more for a big guy than small), and a lot "harder" "no mercy" pull. It took about two passes off your PB.

[kdeupser]

I'm sorry guy's but I have to stop lurking and throw the BALONY flag here. Horsepower has been available since the 50's. And I've seen just as wicked throttle response from carburetors as anything. We just like to live in the land of pretend for some strange reason?

 

I was raised with a father that drag raced in the late 50's and early 60's. I've seen 289 ford's that you would not want to get behind. For the life of me I've never understood why we pretend that only this "new" crop of motor's is the only available horsepower around and or the only motors that can manage a torque curve? Our boat's run either 34 or 36 mph which is a consistent RPM piece of cake for a real motor. It's the RPM band that's the tricky part(and still is). I've seen and done either advancing the cam or retarding it to move the RPM band not a big deal. For a real motor to hold 3,000 RPM or more, c'mon piece of cake! You just probably wouldn't like to ski behind it for the same reason's Bruce and Gator mentioned above.

 

I'm just an average skier, due to I just cannot afford water time much anymore. My PB is only 2@35 not earth shattering. I weigh about 180lbs. In 06' or 07' I skied behind a Malibu with a 385hp Hammerhead motor with Perfect Pass. I was thinking that it would rip my arms off, the swim deck was pounding at idle but the pull felt just like the 340hp Monsoon of another friend of mine.

 

Gator nailed it, when it all comes down to it we do not want a "Dead on" pull. We want ZO to give us 12 different mapping options to cheat/feel the pull of the boat. Don't mis-understand me I want them as well, but horsepower and or torque has never been the problem.

 

I wish I could afford the water around here once again, and I with all of you want that old hand driver from years past as well, but at the end of the day we are not looking for a stronger motor, we want to manipulate the pull. oh yeah, and stay in tollerance. :)

[JonB]

@kdeupser Interesting discussion and I agree with most of your motor & horsepower comments.....however in my humble opinion "prop slip" is the major difference in this discussion. You don't change the pitch & diameter of the prop or the horsepower for each skier thus the different loads will effect the slippage of the prop and the resulting speed of the boat. My 2 cents!

[Drago]

Pp had lag, more than a driver. Good-great drivers did not use gauges, they had organic accelerometers.thats why they couldn't ever really explain how to drive.they were Actually more like ZO, with empathy. And they drove differently for big hitters.

I have to disagree with the "pp helped the big guys". To me, pp was like a bad driver= go in hot and let the skier pull it down"

[kdeupser]

@JonB, I agree. @Drago, I agree as well. Good points. My question is and Jody Seal can probably answer this one, but why do boat's use "stock off the shelf" motor's? Remember a few year's ago when skiflying was a deal they had that SN with the blower on it. I heard horsepower number's of 500 floating around. That's very conservative for a blower motor, but it shown that for that event they were willing to do pretty simple hp upgrade.

 

There are several way's to make cheap, reliable horsepower & torque way above the stock engines used in our boats yesterday, today, and future. And without blowers or turbo's, I just for the life of me can't figure out why we don't leverage it if it's truly needed? Hence the Malibu Hammerhead option. Which if I remember correctly was a simply stroked 350 to a 383 with a mild came. Cheap and easy.

[DW]

I will bet that the hand drivers used sound and butt feel as the calibration for speed, you could probably cover over the speedo and tach once they calibrated themselves to that speed. As for the strength of the pull, I'll venture a guess that the prop is a huge part of the equation, the new CNC props all have a lot more blade area and better holding capability than the older stainless and nibral variants.

 

@kdeupser: correct, I upgraded a 265 Merc to 400 hp very easily with heads/cam/exhaust changes and as you note it is still carbed and very responsive. It will pull your arms off it you desire and makes one heck of a footing boat.

[DooSPX]

I agree with @DW. And about the props, when I upgraded to the new OJ CNC 4 blade over my factory yet mint stainless steel 3 blade 14x18 it turned my MC into a completely new boat! speed holding was night and day as well very minimal prop slip.

[Dusty]

Re: the PP being 'pulled down' by the big people. If the driver was familiar with it, and the boat was set up correctly, I just didn't see it much if at all. The measured all-buoy times were normally within 0.01 seconds of actual- that doesn't seem much give or take either way. If anything, a big skier who chose an aggressive Kx/Px setting would get hot times until the driver 'caught up' with them.

[gator1]

@dusty: The drag down/overshoot happens 6 times during a pass. Maybe 6.5 times depending on if you are late to 6 ball and have to grunt for the exit gates.

 

You can run the boat 46 mph past a set of guide balls, then slow it down at a steady rate to 26 mph as you pass the next set and get a perfect time.

 

Its what the boat speed is doing on an instantaneous basis throughout the pass that creates the feel, and advantage for a big guy if the instantaneous speed is varying more in his favor.

 

Hand drive somebody through the course, and have somebody watch ZO digital speed (Does ZO let you do that, ah, I guess if you set it for 36 and pull 34 it does). Drive by the tach, gassing it when they pull and backing off when they don't to hold RPM (@AB's hot stick method). If you are good, you can get a perfect time. Congratulations. You are a PP.

 

But even with a perfect time, the instantaneous speed as reported by ZO will vary A LOT with every pull and preturn. And if you use the same method with a big strong guy vs a small weak guy of roughly the same ability you will see that the peak vs minimum speed difference is a lot larger with the big guy.

[A_B]

It would probably easy enough to "see" the ZO constant speed differences between a light skier and heavy skier at the same speed and rope length. Build a little weighted pendulum and put it on the floor of the boat and watch how far it moves back and forth during the pass for each skier.

 

I drove PP for the same skiers, same lake, for 12 years, and the first time I drive ZO for a 240 lb skier, my head was going back and forth due to the speed up and slow down, without a doubt in my mind it felt like heavy handed hot sticking. You could feel the LACK of a constant speed.

 

I don't think it was horsepower or torque, as it was 330 hp SN and my brain dead PP was with 3 different SN's with GT40's, so 310 hp. I would bet the GT40 torque would rival the Chevy 330, or best it.

[kdeupser]

Guy's, there is a much simpler solution here and officer friendly can help solve. Simply put a radar gun on the boat. Problem solved, this would show ANY speed variance through out the course. Forget about timing zones, I think it's absolutely ridiculous anyways for the boat to race to the next timing buoy just to keep time.

 

I personally don't believe it's ever been a horsepower, torque, transmission, and or prop issue to maintain speed. We all are searching for that feel. Maybe since ZO has helped us zero in on our tolerances we are ready for a radar/lazer speed tracking system? Then the scorer could have a readout with them as well just like a policeman running a speed trap.

[A_B]

Just don't issue tickets!