Articulation Keel Help With Water Sports?

[d_coyne1984]

So I've seen a decent amount of discussion regarding the articulating keel design, most of it not in favor of it. I think most people like the idea of thrust vectors or Cobra steering enhancments that lift out of the way at speed. One thing I haven't really seen discussed or mentioned is the inherent drawback jet boats have with watersports, the back end likes to pull off course when a skier/boarder pulls hard and how the articulating keel might make a big difference with that. This effect is far more muted on an inboard, I/O, and outboards because of the rudder/rudder effect, and prop.

I am really curious if the major intent of the articulating keel, particularly with the 24'ers where there is a pronounced keel rib that runs the length of the running surface, was to dampen this effect? Otherwise why not just buy the patents for the steering enhancements to keep them out of the hands of the competition and skip the engineering/retooling costs? Can anybody attest to the difference of skiing/boarding behind the boats or driving them while towing with the articulating keel vs. without?

 

[OperationROL]

I can attest to the fact that the back end does not get pulled around like before. I pulled my son last year a few times and could not tell when he was cutting out unless I was watching him. He is 185 or so, but the true test will be when I get to ride behind her. I am significantly more than he is , so if it will slide, it would slide with me behind her. Till this point I have not been pulled behind my boat since no one else in my family knows how to pull me without some sort of speed control. I have Perfect Pass sitting at home. I am waiting for @JetBoatPilot to be finished with the bezel that PP will sit in before installing. Then I will be able to give it the true test........oh yeah, then I have to wait for the water to heat up to bearable.

 

[d_coyne1984]

I can attest to the fact that the back end does not get pulled around like before. I pulled my son last year a few times and could not tell when he was cutting out unless I was watching him. He is 185 or so, but the true test will be when I get to ride behind her. I am significantly more than he is , so if it will slide, it would slide with me behind her. Till this point I have not been pulled behind my boat since no one else in my family knows how to pull me without some sort of speed control. I have Perfect Pass sitting at home. I am waiting for @JetBoatPilot to be finished with the bezel that PP will sit in before installing. Then I will be able to give it the true test........oh yeah, then I have to wait for the water to heat up to bearable.

Thanks for the input! And by the way, I almost like boarding in my wet suit more than without it. I'm what some might call a wuss when it comes to cold, but early and late season boarding/skiing is the best because no one else is on the water. I have an O'neil 3/2mm suit. I highly recommend it!

 

[Cobra Jet Steering LLC]

The design has what I believe to be obvious drawbacks, as you mentioned a large keel will resist turning quickly at speed , the rack and pinion steering doubled the wheel input to reduce the rudder resistance felt by the operator at speed "THEY GEARED IT DOWN" this reduces the response by increasing the amount of input the operator needs to put into the steering wheel to turn the rudder.
The cost of changing the hull design and the increase in the draft of the boat may also be considered slightly undesirable. I also noticed that using a single tie rod to operate the rudder from only one steering nozzle and steering cable would place some uneven stresses on that nozzle and cable. The reason I designed the magnum AK steering was to help with the" SLOW AND FAST " steering response.

 

[d_coyne1984]

The design has what I believe to be obvious drawbacks, as you mentioned a large keel will resist turning quickly at speed , the rack and pinion steering doubled the wheel input to reduce the rudder resistance felt by the operator at speed "THEY GEARED IT DOWN" this reduces the response by increasing the amount of input the operator needs to put into the steering wheel to turn the rudder.
The cost of changing the hull design and the increase in the draft of the boat may also be considered slightly undesirable. I also noticed that using a single tie rod to operate the rudder from only one steering nozzle and steering cable would place some uneven stresses on that nozzle and cable. The reason I designed the magnum AK steering was to help with the" SLOW AND FAST " steering response.

I like how you reinforced the rudder. The first time I saw the factory design I thought that seemed like a little bit of a cheap-out not to have the weight of the push/pull on the rudder shared between nozzles.

 

[Cobra Jet Steering LLC]

As for using the single engine 19 foot boat he currently owns for water sports, to avoid it being pulled all over by a slalom skier or other water sport . His boat would not resist the side pull at any speed . Unless it has a different steering system on it.
I designed the ultimate steering so it can be set to have the fins held down in the water at speed to provide a bite and add quick response to the helm.
Although I often notice people incorrectly referring to that function as locking the fins down, In reality the water exiting the jet nozzle actually provides the force to hold down the fins at speed, the spring is a backup in the event that the engine is shut down and for reverse since the water stops exiting the back of the nozzle when the controls are placed in reverse. But in either case the fins are capable of flipping up if they contact a fixed object or the ground. The factory rudders are fixed if they strike something hard enough it can damage the boat. as posted in this thread

https://jetboaters.net/threads/sank-my-boat.7567/