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Thrust Vectors or Cobra Fins?

Which is better - A = Thrust Vectors B = Cobra Fins C = none

  • A

    Votes: 26 41.9%
  • B

    Votes: 27 43.5%
  • C

    Votes: 9 14.5%

  • Total voters
    62

Art Traver

Jet Boat Lover
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Location
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Year
2007
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SX
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21
Well I got out on the boat twice this weekend, with and without fins. Unfortunately the second day out we had 23 mph winds and didn't get out into the river, just puttered around the canal. I really did not see a huge difference fins on and fins off. Right now the fins are back on. I might try out the Ultimate fins and see if they make a greater difference being they appear ride lower in the water and have a larger surface area.
 

Blenderhead

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Wow. I am amazed that you didn't feel the difference with line correction and steering at low speed. it was like night and day for me....especially when lining up for the boat trailer.
 

Art Traver

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Wow. I am amazed that you didn't feel the difference with line correction and steering at low speed. it was like night and day for me....especially when lining up for the boat trailer.
What model fins?
 

Blenderhead

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IMO both models provided the same steering at slow speed. The Cobra Ultimate AK's that I have now stay down all the time so as to not interfere with my Wake Wedge.
 

Art Traver

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IMO both models provided the same steering at slow speed. The Cobra Ultimate AK's that I have now stay down all the time so as to not interfere with my Wake Wedge.
On both days out it was windy. Saturday was the fins off day and the winds were around 10-15 mph. I managed to get out into the river and execute some higher speed turns, I liked the response / steering input without the fins at planing speed. Docking seemed to be just as difficult with or without fins, mostly due to offshore winds and downstream current. Sunday fins back on was far windier at 23 mph. So maybe not a good back to back comparison with weather differences. The Ultimate fins seem larger that what I have on the boat currently.
 

Art Traver

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Here is the system that I would suggest you install on that boat after you try it naked for a day.

The Cobra Ultimate steering system is our most popular steering system . It is built from aircraft aluminum, the fins are only 3/16 thick and tempered for exceptional strength.
This Patented system, U S Patent 8425269 issued in April of 2013, fits most Yamaha jet boats , the only exception is the newest 21 and 24 foot articulating keel models and yes we have a special steering system, the Magnum A K system for those models.
The ULTIMATE SYSTEM is plug and play. The fins are spring loaded .
The system provides you with exceptional slow speed control for docking and no wake zones.
The ULTIMATE system makes it very easy for guest or novice operators to operate your boat even in congested no wake areas, even handling the wakes of passing boats with ease. So here is where the ULTIMATE earns it's name.
This system is selectable, YOU decide if you want the fins to stay down in the water at speed for water sport activities or for the sake of having excellent control of the boat even in rapid deceleration situations like collision avoidance.
This set actually allows YOU to set the fin depth when in all time mode.
You also have the option of staggering the fins on twin engine applications. You can set the inside fins lower and the outside fins higher to get the exact amount of influence that suits your style of driving and your size boat, yes YOU can set the level of influence in high speed mode to precisely accommodate your boats hull size, this allows you to set the influence level to exactly what you feel your boat requires to meet your individual needs .
Keep in mind if your needs change from time to time all you do is change the settings, no need to go buy a different set of fins.
The Ultimate steering uses a special selectable and adjustable actuator that is NOT positioned in the water below the nozzle so it can't cause drag, get snagged or kick up water behind the boat.
This actuator uses the jet of water exiting the nozzle to hold the fins down at the setting you chose while operating at speed, with the benefit of a backup spring to cover any situation where the pump fails or the engine stall for any reason.
This same actuator can be set to lift the fins up at speed using the same thrust exiting the nozzle to perform that function if you so desire.
This function utilizes the same spring to bring the fins back down when the boat is off plane for enhanced slow speed steering assistance .
The ULTIMATE system also incorporates a special multi function side force stabilizer that eliminates the need to add any stabilizer bars or braces between the fins in the flow of water that can snag things, create drag or create any unwanted water spraying up behind the boat.
So with both the specially designed side force stabilizer and the special actuator we have a unique selectable, adjustable and versatile answer for most Yamaha jet boat owners. From the smaller early jet boats to the largest models available.
Making this system UNIQUE and very desirable!
3 us patents with a fourth pending. Making steering for jet boats since 2001
The M.S.R.P. on a twin set is $450 the buy direct from my web page discounted price for the twin engine ULTIMATE steering is $369.
Cobra ultimate can also be upgraded with fangs below is a picture of Ultimate with fangs courtesy of @Ronnie
Order has been placed for the Ultimate. If you see the comment I inadvertently typed in Ron, and I know it is Jeff. I was on the phone with a contractor named Ron while I was typing. I will try to do a back to back comparison of the older units with the new ones if time permits over.
 

Art Traver

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And by 1:30pm Sunday the new Ultimate's have been installed. Unfortunately we had some severe thunderstorms, so I could not test them out yet. Soon enough.
 

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Art Traver

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Location
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Year
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OK, new Cobra Ultimate's have had their no wake speed test. I am happy to report that the Ultimate's perform much better than the older model that came with the boat. I do have them set to rise out the water at speed, but for this evening we just puttered up the canal and watched a band at Gateway Harbor. I was getting steering response when going from no wake forward to neutral, and I was not getting this before with the smaller fins. What I did notice, and this have been some debris stuck near/in the pump when we were at 3,000 RPM, was a bit of a rooster tail on the port side jet. After we docked I poked my head under the swim platform and didn't see anything and the reverse gates seemed to function OK. Not sure at what speed the fins are supposed to lift out of the water, or begin to lift out of the water. Or if the fins at partial lifting would create this effect. It did not seem to alter the performance of the boat. Hopefully the weathermen are wrong about this weekend and I can get out and try the fins out at speed.
 

Mvold7

Active Member
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Year
2017
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AR
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Anybody try the cobra viper for single engine 19' boats?
 

Cobra Jet Steering LLC

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Art Traver

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As an update to my earlier post regarding the Cobra Ultimate fins. I have them installed to rise out of the water at speed and have tested them out at various rpm's. At idle speed you can definitely tell you have them installed as the steering response is greatly improved over being naked or finless. Without the fins I needed to bump the throttle a bit to get a decent steering response, with the fins I have found low speed maneuvering much easier, even with just running one engine at forward/reverse idle. Once you start to add some rpm's, say around 3,000 or so, you can tell you have fins on as there is some resistance in the steering wheel. I am going to do some further testing by adjusting the depth of the fins. This resistance disappears as you approach planing speed. Once on plane you can't tell you have fins. The steering wheel loosens up and steering is just the jets, allowing you to carve some fun turns.
 

Cobra Jet Steering LLC

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The fins are designed to allow you to change their function and their input , so if you choose the UP at speed setting they actually go up at the transition between slow speed and planning speed I accomplish this by not placing anything between the fins under the nozzle because this would cause drag, disrupt the water and cause annoying spray behind the boat.
So this keeps them in the water above idle speed and lifts them at planning speed however there is actually about 10 percent of the fins still making contact at speed so you still have just a small amount of extra steering when you are up on plane. Setting them to stay down all the time is more for water sports and people who like added steering for quick turns and continued control when rapidly decelerating and turning at the same time or in rough or heavy boat traffic conditions so the boat stays it's course in waver or wakes etc.
 

Cobra Jet Steering LLC

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Ok the first set of the VIPER N K II steering on a twin engine 24 foot Yamaha ready to go out and test.
 

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Cobra Jet Steering LLC

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I know my steering does especially important on the 21 foot boats
 
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