Redneck Perfect Pass

eric lavine wrote: I would think you wont need a paddle since you have sensor on the prop shaft, the unit should sense the load on the shaft and automatically compensate with more throttle, i think it will be pretty accurate at keeping the boat to speed, even if your running ballast

You could put more or less magnets on the shaft to give better/worse resolution too.

Tim

Yes we ride with ballast but that is not what really makes a difference. We pull so hard against the rope doing certain tricks that I can pull the boat off plane if I want to. My buddy is really big and built and when he pulls or rails the motor has to gain 400-500 rpm's sometimes just to maintain the same speed. A shaft sensor doesn't compensate for prop slippage and that's why a good perfect pass unit uses a GPS speed signal to maintain speed. My boat pulling wakeboarders can run anywhere from 12- 26 mph at the exact same rpm, it depends on the rider's weight and how hard they pull against the line. I agree it doesn't change much pulling slalom skiers but your not close to your planing speed when pulling them like pulling a wakeboarder which is usually around 20-23 mph. I can keep my boat within 3 mph but that feels like a big difference when your riding unlike skiing where a few mph is not that noticable.

Ballast does make a difference because it changes the angle of attack that your boat rides in the water. Once that angle of attack reaches a certain point your boat essentially stalls and looses plane and is now just pushing though the water. Couple the extra weight with some hard pulls and the ballast makes a difference.

Tim

eric lavine wrote: Doc, i have you beat, i drove a 1972 pinto around for 2 months that i paid 60 bucks for, the floor was a no parking sign, and the cable broke to the carb so i tied a string to carb linkage and brought it thru the firewall and it was hand operated from that point

Funny story. Thread jack for a min...

My uncle, who was driving a '78 Pinto, was stopped for not wearing his seatbelt. He asked the state patrol officer, "Would you strap yourself into a '78 Pinto?" Obviously the officer wasn't amused and wrote a ticket.

Had I been the officer, I would have let him go!

As far as the "cruise control" I'm really curious about the system. I've learned enough at work to barely be dangerous with controls. I'd like to see the trigger wheel installed on the shaft (pics please). Also, is the system tunable? For example, can the PID gains be adjusted?

I'll strongly consider installing one if I can get more info. I could really benefit from one. If the price is right I might go for it!

Matt

The easiest way to describe PID gain is the speed at which the controller makes adjustments. For example...think about pulling someone skiing. If you are running 1 mph too slow and you push the throttle up the boat might increase in speed by 2 mph (just for example). You pull back and the boat decreases speed by 2 mph. As you keep doing this you can never hold the correct speed. You are trying to run 26 but the boat is at 25. Push down...27...pull back...25...push down 27...this continues and you never reach 26. Another example...as above boat is running 25 and you want to run 26. You push down just a little and the boat runs 25.1 ... a little more and 25.2 ... a little more and 25.28 ... a little more and 25.30 ... a little more and ...25.31 ... at this rate you will never get to 26.

P=porportion, I=integral, D=derivative. Typically D=0. P and I values are tuned to prevent the conditions above.

I hope this makes a little sense.

If you want RPM control you should be able to use the tach signal (or ignition trigger signal) as it is a magnetic trigger! The distributor runs 1/2 crank speed so there are 4 triggers per rpm, assuming you are using a magnetic trigger which most electronic ignitions do. It should work with a points trigger also as they basically do the same thing. In other words, you might not even need the trigger on the output shaft, which it sounds like you have had some trouble with! The engine and shaft RPM's are 1:1 or whatever your trans ratio is.

I'm using a "crank trigger" on my race car. It has magnets in the "wheel" that trigger a pick-up thus triggering the ignition system. The magnets are installed by drilling parallel to the crank centerline so they don't come out. Maybe this design will help with your installation.

I'm all about some redneck-rigged-up-stuff that works and everybody says, "How'd you do that?" Then you can say the famous last words, "Hold my beer and watch this!"

Matt

BD will it hold the RPMs on a incline?

Raindog, I'd like to look at the output of the gps unit your speaking of and compare to what the Cruise module likes to see. Billy do you know resolution capabilities of the cruise? And what the differential needs to be before it decides to make a correction? You guys might have invented a 350.00 gps based perfect pass.

I printed the instructions of the internet and started looking through them. I have little doubt this kit will work, and I bet it can be massaged to work really good!

For the money (I think you said ~$100) it could be a dream come true for us "red necks."

I have some ideas how to make a rope operated switch (like the one on perfect pass) work.

It appears the gains are not adjustable on the unit with the exception of a coarse adjustment. The kit has 3 levels of "sensitivity." However, this might not be a problem because the servo could be installed in such a way as to change the mechanical advantage it has on the carb linkage therefore fine tuning the "gain."

This is a really neat kit and could work well on our boats with some fine tuning.

I'm definately interested!

One precaution. ANY TIME you start fooling around with the carb linkage be VERY CAREFUL as they can hang open if everything is not perfect. Test it a few times with the engine off and know to turn off the key if it hangs open. I've seen some really bad things happen from linkage hanging open!

Heres some pics that Doc sent me of his set up.

I applaud your effort Doc! You saved a few pennies and your foot.

Matt,the last pic shows the location in the upper front corner of the motor area. Directly behind the drivers seat.
The description of the "pull to open" as "slip linkage" and a good desriptive. Spent more time there than on the wiring and install on the rest of the parts.
As far as using it in the "slower mode" I have used it from 1000 to 3500 and see no difference in setting nor holding any given rpm.
Hard turns seem to have little effect maintaining a set speed.More testing will be done again comr the weekend.....Boat dr

A brick on the pedal wouldve done the same thing

The servo is indeed vacuum , your cam cannot be "wilder than mine. The tech said all it needed was 9" of vacuum and if the motor cannot hold that, a canster seems to be an easy fix. Some smaller 4 cyl. cars do not have enough at cruise so this was the fix.
I saw several of the motor drive type servo's , but chose the vacuum type for ease of install and the dependability factor.
Water and drive motors do not mix...................Boat dr

eric lavine wrote: A brick on the pedal wouldve done the same thing

This is divorce insurance.

Steve and fellow CCFans.....Got it going now.
Just got off the lake and everything works great, much better than expectations.
Seems as if the last round of glitches was due to the "Brake interupt" was not grounded properly. After several hours of checking and re checking that was all that was left.
Set the PPM at 2000 turn #3 and #7 dip switches to on all else to off.All functions work fine,speed up is about 75 rpm's per bump in both the up and down modes.
1500 rpm's hold rock steady, have not tried a skier but hard turns yeild no drop in speed.I have spent a lot of time and less than $150.00 to get the desired results.............Redneck Perfect Pass