HydroJet Pro EXPLAINED

[HydroJet Pro]

Can you post videos of the tests you did that prove your system turns faster at idle and slow no wake speeds? I assume you must have done something to prove your system given that you are entering a market with 2 well established products already in place. Sorry if this seems a little like the "shark tank", but I for one am a little skeptical that fins in a raised position will have a better rudder effect than fins below the boat. I also think your diagrams don't do a good job of visualizing laminar and turbulent flow. At a no wake speed, I agree that water flowing under the boat will be laminar, but almost immediately upon passing the transom this flow becomes turbulent. So you need as much surface area as possible in this flow to effect a turn. Which brings up another question-can you provide the square inches of surface area of your fins vs TVs and Cobras? I'm curious to know how much more surface area they have.

We appreciate everyone's interest in our product, and I believe that every question is a fair question.
I apologize for the quality of the diagrams. We will work on providing a better way to help visualize the flow described.

You also stand correct. As the boat accelerates the flow directly behind it becomes turbulent. However, the intensity of such turbulence is very minute at low speeds. So even though the fins don't see 100% laminar flow between 3 and 6 knots they redirect the thrust from the nozzle much more effectively, improving the overall steering.
We will provide an area comparison, along with other test data on our website hydrojetpro.com ASAP.

 

[0627Devildog]

they redirect the thrust from the nozzle much more effectively, improving the overall steering.

Can you provide an illustration of this point?

 

[HydroJet Pro]

Can you provide an illustration of this point?

When on low throttle our system will be directing the flow as illustrated below. Without fins, the flow leaving the nozzle dissipates much quicker, especially at low speeds when the impeller is not producing as much thrust. By having the fins directly behind the nozzle we can enhance the steering ability of the actual jet.

*This picture is an illustration. Not an actual underwater photograph.

 

[swatski]

@HydroJet Pro
IMHO it's one thing to come here with a new idea that you are testing, or trying to improve an existing product or mod. It's another thing all together to come here to push a commercial product that blatantly encroaches on well developed ideas and (in all likelihood) patents of individuals who are highly regarded members of this forum.

Your illustrations, artistic renditions of flow, thrust, etc. are quite pretty and captivating. To the untrained eye. But, for anyone who has actually put time and effort into improving these systems - these are flawed to the point of being amusing.
Case in point: the rudder effect idea of your system (operating in forward). No matter how you draw it in your schematics - in boat models where your system could be employed the gates (and the fins) are out of the water at any forward speed. That has been discussed in the thread cited above, so it is a waste of time here. Or - the idea you illustrated above (with the fins directing the flow) - is just another gimmick. The fins out of the water don't influence anything in these boats.

I do not mean to be rude. But, all joking aside, I find your conduct here to be poorly suitable (not cool) in the circumstances
Again, this is MHO only.

--

 

[4x15mph]

@HydroJet Pro , if the fin bangs against a beach bottom or object, since it is attached to the throttle assembly (gate cable), wouldn't any shock create force on the cable and bucket/gate? We would probably all welcome a comparison video including a Rotax entry that uses their own directional/steering aid (nozzle).

 

[Speedling]

What i understand from this whole this is basically instead of making "rudders" below the hull he is making it more of a jet director making the jet more effective at turning.
At slow speeds when you are below 8-9 mph the fins also are getting water from under the boat because at that speed (no wake mode) the water comes up over the pumps and the fins are effective.

@HydroJet Pro don't let them get into you too much, there have been billions of fin discussions that have left many with a bad taste in their mouths. I am always glad to see innovations come around and your product does something a little different.

That being said, i am not taking off my fins to put on another brand.

 

[Gym]

I also have come to understand, as @Speedling, what is going on here. It's like the barrel of a gun (not rifle) focusing the thrust of a bullet to give it more range. The thrust from the jet nozzle is similarly being focused to increase resulting effect increasing steering response. I also will be keeping my current fins as I need fins in the water all the time due to chop, tidal action and boat wake.

 

[jlcj7]

I am not one to slam anyone for trying to invent a product or innovate something... I also have appreciated the debate of what is better on certain fins... For me, this is all noise until there is an independent test (video) of your product versus the other products under different situations...

One side note though, i am not a lawyer and i have not read anyone's patents, but i still struggle to understand how this doesnt infringe upon @JetBoatPilot product... (maybe it is simply method of attachment...which you are clearly trying to differentiate from the others...hence the debate)...

Anyway, if you are here to participate, like the other members, Welcome...

 

[subysti]

@HydroJet Pro I currently have thrust vectors and I would be willing to give these a try if you want to send me a set. The only take a few minutes to change out so why not give it a shot. I can also video the results and post. But I believe you don't have set for 2016 do you?

 

[BigN8]

I am a die hard "finless" jet boater so I have no dog in this fight. I know and understand both the Cobra design and the Thrust Vector design because I have watched and participated in the fin debates for the last 6 years. To me you are stepping on toes with this design and using smoke and mirrors to step around some patent issues. I understand flow characteristics having studied "Thermodynamic heat transfer and fluid flow" while I was in Naval Nuclear Power School and yes I know what a freakin knot is. I spent a good portion of my life cruising "3 knots to nowhere" on that guided missle cruiser that is my avatar! I still don't buy it. And no video demonstration will make a difference because we all know that there are so many variables that can skew the demonstration to benefit one fin over another. My opinion you have 3 major flaws with this design.
1. You ripped off another guys patent
2. The fins are plastic. Water and UV will drive the plasticizers out of their molecular bond and turn that plastic brittle, then force will be put on them and they will crack or break. 99% of the boating world here store their boats out of water either on a lift or a trailer, so these plastic fins will be exposed to UV most of the time. Unless you can show that the plastic you are using has a high amount of Elvaloy polymer or has undergone 10,000 hours in an accelerated weathering test, I would be suspect of using plastic.
3. The shape of the fin is a safety hazard. The lounge area design of the Yamaha jet boat is one of the most appealing aspects of these boats. It invites a social interaction at the rear of the boat with people lounging on the back of the boat and others in the water. If anyone kicks their foot wrong while in the water at the rear of the boat with your fin installed it is going to result in an injury. Basically that is why the thrust vectors and cobras have rounded designs.

 

[0627Devildog]

I am a die hard "finless" jet boater so I have no dog in this fight. I know and understand both the Cobra design and the Thrust Vector design because I have watched and participated in the fin debates for the last 6 years. To me you are stepping on toes with this design and using smoke and mirrors to step around some patent issues. I understand flow characteristics having studied "Thermodynamic heat transfer and fluid flow" while I was in Naval Nuclear Power School and yes I know what a freakin knot is. I spent a good portion of my life cruising "3 knots to nowhere" on that guided missle cruiser that is my avatar! I still don't buy it. And no video demonstration will make a difference because we all know that there are so many variables that can skew the demonstration to benefit one fin over another. My opinion you have 3 major flaws with this design.
1. You ripped off another guys patent
2. The fins are plastic. Water and UV will drive the plasticizers out of their molecular bond and turn that plastic brittle, then force will be put on them and they will crack or break. 99% of the boating world here store their boats out of water either on a lift or a trailer, so these plastic fins will be exposed to UV most of the time. Unless you can show that the plastic you are using has a high amount of Elvaloy polymer or has undergone 10,000 hours in an accelerated weathering test, I would be suspect of using plastic.
3. The shape of the fin is a safety hazard. The lounge area design of the Yamaha jet boat is one of the most appealing aspects of these boats. It invites a social interaction at the rear of the boat with people lounging on the back of the boat and others in the water. If anyone kicks their foot wrong while in the water at the rear of the boat with your fin installed it is going to result in an injury. Basically that is why the thrust vectors and cobras have rounded designs.

 

[HydroJet Pro]

We really appreciate all of the input from this community. It was one of our first customers who directed us here with regards to the discussion over our product. The reason we created this thread is to simply help explain the reasoning behind our design.
While we believe we have changed the approach to a known problem and come up with a different design solution, we strongly agree that the competition works. Our team has owned various jet boats for many years and all of us had both systems installed. They have worked great on all our boats and we have had no reason to complain. Our founder, who has a strong Aeronautical Engineering background, initially approached the maker of one of the other products with suggestions for improvements, but they simply didn't seem interested in pursuing it. Since then, with his engineering and manufacturing capabilities he continued to refine and perfect his ideas, resulting in HydroJet Pro.

My opinion you have 3 major flaws with this design.
1. You ripped off another guys patent
2. The fins are plastic. Water and UV will drive the plasticizers out of their molecular bond and turn that plastic brittle, then force will be put on them and they will crack or break. 99% of the boating world here store their boats out of water either on a lift or a trailer, so these plastic fins will be exposed to UV most of the time. Unless you can show that the plastic you are using has a high amount of Elvaloy polymer or has undergone 10,000 hours in an accelerated weathering test, I would be suspect of using plastic.
3. The shape of the fin is a safety hazard. The lounge area design of the Yamaha jet boat is one of the most appealing aspects of these boats. It invites a social interaction at the rear of the boat with people lounging on the back of the boat and others in the water. If anyone kicks their foot wrong while in the water at the rear of the boat with your fin installed it is going to result in an injury. Basically that is why the thrust vectors and cobras have rounded designs.

1.We are engineers, not lawyers. However, our patent attorney has already done extended research and is confident that we are not infringing and that we will be eventually granted a patent on our improvements.
2.The fins are plastic indeed. A very specific type of plastic however. HDPE Marine Seaboard, which is a high density polyethylene sheet formulated to meet the specific requirements of marine and other outdoor environments. In addition, special post-production treatment enhances its ability to withstand the effects of salt water, moisture and direct sunlight. You can check out the ASTM standards and material specifications here: http://www.aetnaplastics.com/site_media/media/attachments/aetna_product_aetnaproduct/61/Seaboard.pdf
3. We would have preferred a much more aggressive shape for more efficiency and effectiveness. However, like you said, sharp corners may be dangerous, so we compromised. Safety was a major concern during the design process of the fin. .We made sure our edges and corners were safe and that no harm will come if someone accidentally bumps into these. Due to the possible damage to people or objects, when backing the boat on a trailer, material selection was also an important safety concern. We looked at various types of plastics and metals, along with different kinds of finishing and radii. After testing a variety of prototypes, we believe we have found the best compromise.

Thank you again for all your feedback. We hope to be able to keep answering all your questions.

 

[HydroJet Pro]

@HydroJet Pro I currently have thrust vectors and I would be willing to give these a try if you want to send me a set. The only take a few minutes to change out so why not give it a shot. I can also video the results and post. But I believe you don't have set for 2016 do you?

@subysti our 2013 and above models are still being tested. We will let you know as soon as we can get them into production. Thank you for your interest!

 

[M@__]

The reason we created this thread is to simply help explain the reasoning behind our design.

1.We are engineers, not lawyers. However, our patent attorney has already done extended research and is confident that we are not infringing and that we will be eventually granted a patent on our improvements.

I'm hard core finless also. Honestly I don't see the difference between TV or Cobras so if this is a copyright issue maybe that is too, unless they are licensing this to one or the other. Legally I could care less, and I suspect a good lawyer could make a case for either side.

As a professional engineer with a PhD and actually teaching fluid mechanics to college students I can tell you two claims are not scientifically correct, and one is just completely wrong.

Technically what you are calling "turbulent flow" is actually "ineffective flow." There are special conditions that need to exist for water to behave in a laminar way, and that depends on the Reynolds number. In almost all cases water behaves as turbulent flow. The effect that you are describing is valid, but not the correct vocabulary for a fluid mechanics engineer to be using.

More importantly there is no way that this system enhances the jet action. Jets work on the principle of increasing velocity which causes an increase of "momentum" of the water, which drives the boat forward. Comparing the velocity of the water leaving the jet with the velocity of the water between your fins we see that the velocity in the jet is higher, therefore the jet on it's own has a greater thrust than the fins could have. Additionally, the speed of water leaving the jet indicates that it wouldn't actually contact your fins at all. So essentially you are left with a fin that acts as a rudder at some speeds and not at others. Even your own illustrations discount any amount of jet thrust being redirected. I'm not sure you are actually making this claim, but other posters have, and it's not correct. None of the systems interact with the jet or improve or reduce the jets effectiveness.

I do personally believe this is an innovation. The ability to raise or lower the fins seems like it would be important to people. Most complaints that I hear are about low speed and about reverse, which this does seem to have a significant impact on.

If you are trained as engineers then I would suggest you doubling down on some of your figures and explanations. If you are not a graduate of an ABET accredited engineering school then I suggest you not make statements that you are engineers, unless you drive a train or something like that (this is a bit of a point of emphasis to me and I apologize for the soap box approach I'm using).

Respectfully,
Matt

 

[BigN8]

This kind of reminds me of the saying, "don't bring a knife to a gun fight"!!

I still stick to my belief that low speed handling is more greatly affected by load displacement inside the boat. When my teenage daughters sit in the bow I have way less control of the boat. The stern tends to over drift on sharp turns. When they sit aft I don't see the same drift characteristics. It must have something to do with changing the center of gravity or something. Next time y'all are out try it. Load the now with 350-400 lbs and nothing aft and make sharp turns. Then shift the weight aft and try the same turns.

 

[Shuck Water]

@HydroJet Pro Aren't you glad you joined this forum..... Side note, are you based up at Addison Airport?

 

[subysti]

I'm an electrical engineer so can I still chime in! You are a PhD engineer and driving a 2002 lx?

 

[Scuba_ref]

@subysti our 2013 and above models are still being tested. We will let you know as soon as we can get them into production. Thank you for your interest!

If you are sending them out to try then I'd take a set for a 2005 AR230. I had the original Cobra Fins with sharp as ginzu knife edges. I replaced those with TVXLs and the one on my port nozzle shakes like a bugger at speed increasing the noise of my boat and causing all sorts of spray. I'm not emotionally aligned to any fin product, I just want what works best for me and if that means more legal competition them I'm all for it!

 

[HydroJet Pro]

If you are trained as engineers then I would suggest you doubling down on some of your figures and explanations. If you are not a graduate of an ABET accredited engineering school then I suggest you not make statements that you are engineers, unless you drive a train or something like that (this is a bit of a point of emphasis to me and I apologize for the soap box approach I'm using).

Wow! Welcome to the forum @M@__ ! Not quite sure what ax you are trying to grind. We can assure you we are real, Aerospace Engineering professionals, graduated from real universities, like Embry-Riddle Aeronautical University, world renowned for its Aerospace Engineering program. In our comments in this thread, we are trying to provide information that is accurate and easily understood without overly esoteric technical jargon. NASA, along with every major scientific community, agrees that any flow with a Reynolds number above 4000 is described as turbulent flow. We decide to stick with NASA, but luckily we live in a free country and you are welcome to your own opinion. We do not think getting bogged down in the technicality of the vocabulary is useful to the audience of this forum. To the best of our knowledge all the information we provided is correct and true.
We would prefer, to stay out of this sort of conversation however, since it benefits no one in this community. We will do our best to keep answering any questions or doubts about our product, not fight for who is the "most accredited engineer". Our only interest is to make jet boating as safe and fun for everyone as possible and maybe one day join the train industry as well.

@HydroJet Pro Aren't you glad you joined this forum..... Side note, are you based up at Addison Airport?

We are glad to have joined this forum. Most people seem to have real valid questions about our product functionality and show as much love for jet boats as we do! And yes we are located at Addison Airport.

If you are sending them out to try then I'd take a set for a 2005 AR230. I had the original Cobra Fins with sharp as ginzu knife edges. I replaced those with TVXLs and the one on my port nozzle shakes like a bugger at speed increasing the noise of my boat and causing all sorts of spray. I'm not emotionally aligned to any fin product, I just want what works best for me and if that means more legal competition them I'm all for it!

Thank you for your interest. Simply email info@hydrojetpro.com if you would like to review our product and we will provide you with more information.

 

[Bennie]

@Julian @Murf'n'surf - Can we get a "popcorn" emoticon? I feel like I could use some watching this Maury Povich show

I'm an electrical engineer so can I still chime in! You are a PhD engineer and driving a 2002 lx?

You almost had it... then you forgot your question mark.... geez
(sorry @subysti , I had to)