Zero Off

[Skihack]

There is a lively discussion going on over on the waterskiforum website about none other than our most favorite topic: Zero Off.

I have never really had the chance to experience it until this week. I do not ski it and it is very rare that I drive a boat with it.

First thing I noticed driving a 2009 SN with ZO installed and a PCM 343 engine was how incredibly responsive it is. I normally drive a 98 SN with a GT40 engine. Path straight down the middle of the course, maybe a slight turning of the nose when the skier switches edge not much though since the skier is only 100 lbs. and runs mid 32 off's. So, all in all pretty much right down the middle. What I have noticed with the ZO powered boats is that if you deviate from a direct center line the boat will lurch forward with the nose coming upward. And it doesn't take much, maybe a couple of inches. This would make sense to me since I believe the course is mapped and GPS is insuring that the boat goes exactly that speed from point a to b. So, it seems to me if the boat driver does not drive perfectly straight, he or she will cause the boat to surge more than it normally would. Amazing to me that a slight deviation could cause such a drastic increase in speed. Thus, this is why the heavier skiers are getting hammered. The drivers are trying to counter only to cause much more acceleration. I think the SN 200 design is trying to address this with better tracking and higher rpms. Hopefully, some tournament certified drivers will chime in on this and give their expertise and opinions on this subject. 

[Drago]

A little too hot over there, but: I'm fairly heavy and ZO is the best thing that ever happened to my skiing. Consistently 4 buoys better in tournament performances and practice. Ready for this? I think ZO let me go to a shorter ski/ deeper fin setup,  and I can now maintain speed through the turn without dragging around like I did behind Classic, or being pulled slow until the boat gasses me immediately after the 3 ball with SG. Gotta say, though, timing and rhythm rule, and the gates are dramatically different, so I empathize with the skiers out there that don't have modern club boats.

Less is more, 

Drago

[clemsondave]

I assume at 6'5", CP is close to 200#. Imagine what he could do if ZO was not 'faulty'! I too, sympathize for those that have no access to ZO, but cringe when I hear words like 'faulty', 'sucks', 'flawed', etc. The '1' settings seem pretty smooth to me (I prefer 2s and 3s). The only way I can see it being smoother is if you let the speed really dip when you pull, which is against the rules.

[ForrestGump]

I've driven a lot of ZO boats and I've never noticed the boat lurching forward as you say.  It will definitely give rpm input when the skier  loads. But I've never experienced it raising the nose even if you're a foot off.  It uses differential gps to determine speed so it doesn't matter which direction you point it. You can pull a skier outside the course and it will still time and give you correct speed.  Where you will git lurching and surging is if there's any chop or if driving over rollers. 

[Skihack]

It was very, very rolly. Worse I've ever seen, sort of like being in a pool. Boat moving around by rollers. Come to think of it, the MC TT never lurches forward but the lake it is on doesn't have rollers.

[ForrestGump]

That's what it is, then. The ZO has an accelerometer built into the head unit. It's pretty sensitive and picks up the velocity changes as the boat goes over the roller and the end result is a small surge.  

[LeonL]

I agree with Shane.  It wasn't a direction deviation that causes a surge.  The boat will accelerate at the end of the course when you swing to drop a skier (if you haven't already pulled the throttle somewhat) and that takes a good bit of direction deviation prior to that happening.

[east tx skier]

The first version or two of Perfect Pass SG used to surge if you didn't disengage it in the turn.  Fixed with a software update.  Is there really an accelerometer in ZO?

[thager]

Yes, 2 I believe if I read it right.

[Steven]

I have to agree with the roller comment. We see that alot here in Canyon Lake. We share an area with the Wakeboard club. They ride up stream from us and are supposed to turn around before a dog leg in the lake. If the Wakeboarders turn around past this point they'll send rollers into the course and then you'll get the surging you're talking about. In calm waters the only rpm change is from skier load.