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Lateral Thrusters High Speed Video Completely Out Of Water

Sbrown

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So you're telling me if I can recycle the water from the jets back into the jets... and add wings.. I can fly with my boat? @swatski is this on your mod list yet?
I think all you have to do is recycle Redbull into your jets, 'cause it gives you wings (at least the ads say so)
 

haknslash

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Yes and this is why things like the flyboard actually work. Notice none of the water from the jet is shooting into the water but rather the forces from the jet are pushing the rider/board.

 

AZ Native

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Well I’m glad God invented Physics, otherwise jetboats wouldn’t be much fun, just another hole in the water.
 

adrianp89

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I've always wanted to try those things. I am more curious what the guy in the back is doing... doesn't look he has a wake to follow.
 

Sbrown

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I've always wanted to try those things. I am more curious what the guy in the back is doing... doesn't look he has a wake to follow.
Good catch, I didn't even notice him.
 

seanmclean

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Oh that guy? Don't mind that guy. He's just scooting along on his back to the future board.
 

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The guy is actually riding a jet propelled surf board I see those occasionally.
 

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But, no life jackets?? :hungover:

This has been bugging me for a day now, but I think I figured out how the nozzles turn my boat even though they are out of the water. It must be the impact of the jet water stream hitting the side of the deflected nozzles like undisturbed air hitting the deflected rudder on the tail of an airplane, basically pushing it to the right or left (or not). I don't have an articulated keel with a rudder to enhance turning or fixed fins sticking down in the water. I showed Will's video to some of my staff today and they were also blown away.
 

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Cobra Jet Steering LLC

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Those have been around for quite some time actually, they are difficult to operate and I was advised they were also very expensive as well.
 

adrianp89

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About 10k. Not worth it.
 

Cobra Jet Steering LLC

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As far as what the original video is showing and the obvious reason for it seems to have been lost in the wind.
Obviously lateral thrusters were intended to move the back of the boat sideway when the boat is being used in reverse therefore not on plane and they would then be in the water and the hull would also be traveling backward so this device would certainly be creating drag while backing the boat as it would be the leading end of the boat .
The function of this part obviously utilizes the raw reverse thrust exiting the bottom of the nozzle to move the back of the boat sideways.
So why show this video ?
Obviously to prove that while the boat is on plane these parts are in no way creating any drag or reducing the top speed because they are shielded by the hull so if someone noticed a dramatic positive increase in top speed using my steering and mega fangs on a boat in comparison to using the thrust vectors and lateral thrusters on the same boat, the lateral thrusters by design could not be responsible for any reduced top speed.
I agree with that and I have said this in the past, obviously no drop in top speed could possibly be caused by this component.
So if there is a loss of top speed it would need to be from some other cause.
That should pretty well sum up the video.
Now as for the picture of the back of the boat on plane posted by swatski.
Now that is impressive because it shows the huge amount of force being dealt with by the nozzles and the rudder, those are some seriously tough nozzles but it also shows us how high up the nozzles are when the boat is at planning speeds .
If you take a look at the location of the nozzles and the rudder and you compare these to the location of my fins on a nozzle you should find it easy to understand that even my fixed fins have an automatically varied influence as the boat gets up on plane the influence is reduced simply by removing a portion of the fin surface from contact with the water because the boat needs less contact at speed but it still has sufficient contact and influence to allow you to steer the boat as you rapidly decelerate in a turn. Or during water sports and to keep the boat handling correctly in rough conditions or just tracking straight on plane. So that picture certainly does speak a thousand words.
 

seanmclean

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Man, you're right. Those LTs must create HUGE drag in reverse. Wonder how the boat even moves adding a few square inches of surface area drag in comparison to you know.... the rest of the boat.
 

CAM212SS

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Man, you're right. Those LTs must create HUGE drag in reverse. Wonder how the boat even moves adding a few square inches of surface area drag in comparison to you know.... the rest of the boat.

No doubt. So annoying some of the posts being written against his competitors products.
 

MattFX4

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Man, you're right. Those LTs must create HUGE drag in reverse. Wonder how the boat even moves adding a few square inches of surface area drag in comparison to you know.... the rest of the boat.
lol yeah. I don't plan to add any steering enhancements to my boat, but if I do it will be from @JetBoatPilot for sure. The lateral thrusters are a genius idea, and IMO work differently in a better way compared to a fin or fang or whatever the hell you want to call them.
 

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So - FWIW - here is one of my favorite jet boat pics - that (I think) @Williamsone46 posted some time ago - showing a 2015+ 240/242 hull/stern/jets at planning speeds:


Pretty cool!

--
This is the ONLY acceptable use for a selfie stick!!! hahaha
 

Cobra Jet Steering LLC

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Haaaa well hopefully a few people had the ability to see that I was trying to make you see the obvious and do a little thinking as for your choice of parts I say do what ever you want but here is the real point of my last post.

The obvious issue with boats being difficult to back and control is due to the resistance in the hull design.
Obviously the back of most boats was never meant to lead the hull so you are dealing with a huge amount of drag , thus needing more power or thrust to move the hull backward in the water and obviously the hull is completely in the water experiencing the full drag effect including current resistance when it is being driven backward.
So having the water shoot out and spread out from the bottom opening as Yamaha does has never been an effective way to get a jet boat to steer in reverse.
You obviously need a lot more thrust to move the boat in that direction and you need more focus of the jet water to steer the boat accurately not to mention deal with wind ,current, waves etc. encountered when operating in the real world.

This is why I chose to handle the situation in a different manor , back when I offered the fangs to utilize more of the existing thrust already available to get the job done in a way that people are accustom to as opposed to reducing the forces available.
Also adding in the power steering effect in and enhanced steering in forward as well as reverse to obtain the most features and benefits .
Jet boats are and always have been a challenge in any direction, their lack of steering in all situations has been their Achilles heel .
Most jet boat manufacturers went under due to people not liking the JET BOAT FEEL !
Currently I see that people are purchasing jet boats for a variety of reasons just like prop boats only with less maintenance & less up front cost .
I believe these are a lot more fun once you can steer the boats and feel comfortable behind the wheel once you eliminate the fear in the pit of your stomach from loosing control of the boat unexpectedly while towing skiers, or enjoying water sports or cruising around with total confidence that the boat will respond to your input in the helm allowing you to drive the boat like any other boat .

Jet boats are now being taken seriously by a lot more people And after 16 years of building aftermarket steering for them I believe I have made a contribution to the evolution of the jet boat market.
Also please remember I offer special side force stabilizers for people with my Ultimate steering who want to go the lateral thruster direction, my magnum A K system and my next release will also be cross compatible with my mega fangs or lateral thrusters for your convenience, so I don't have a problem with people wanting those.
That being said I just think the mega fan setup is more for less.
Now please understand I totally expect the trolls to come out when I post things and I usually don't see most of their posts thank s to the ignore option offered on this web page .
I would suggest if you do not agree with my posts perhaps you should put me on your ignore list .
 

haknslash

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"Most jet boat manufacturers went under due to people not liking the JET BOAT FEEL !"

I am not so sure that is why the other brands stopped making them. Kawasaki pulled out because nobody took the Jetmate serious, and how could they when it was basically a bath tub with a jet pump controlled by a joy stick lol. They were going through an identity crisis back then experimenting with all sorts of weird models like the TS and SC PWC's and the Jetmate boat. Other lesser known brands popped up but didn't have the sales base to survive long. In the mid 90's SeaDoo began making sporty "boats" but pulled out a few years after because of lack of sales and sold off their design to Scarab later on. Most of the SeaDoo boats were very small and not really family-friendly, more so buddy-friendly for ripping about. It wasn't until the Islander, Challenger and similar larger models did they start to attract 'boat folks". Those larger models along weren't enough to carry the boat lineup. The rest of their lineup was something more closely resembling a "PWC w/ storage" and seemed to attract mainly the youth but was out of their budget compared to a PWC. Yamaha came along in the mid 2000's and has been there ever since. Chaparral came on a few years back and seems to be making nice boats. Chaps nor Scarabs have a keel or rudder and are still selling today.

Point is that the boats that seemed to not last were boats that were itty bitty, rode like crap, lack of storage, practicality, etc. Once manufacturers began taking things more seriously with larger and more mature designs in mind, the sales have shown them to be successful.... fins, keels or none at all. None of that mattered IMHO. It wasn't until recently that Yamaha even began putting a keel on the boats, so I am not a believer that older boats died because of "jetboat feel".
 
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2kwik4u

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Honestly, I've held back responding to this thread because I'm trying to avoid arguments. But I can't not answer your question either. In the simplest terms, all of the force that makes your boat move happens inside the pump. The reason it turns when you change the angle of the nozzles is due to something called "thrust vectoring" which simply means that when you change the angle of the center of the low pressure area (the water escaping the high pressure of the pump), the center of the high pressure area (inside the pump opposite the nozzle) changes as well. And for the record, boat propellers, airplane propellers, helicopter rotors, aircraft wings and our jet pumps, all work on the same physics principles and to a certain extent, yes, it actually is rocket science. It really works off of two simple principles. 1: Any gas or liquid will flow from a high pressure area to a low pressure area. 2: All actions have an equal and opposite reaction. As an answer to your last question, yes the pumps are pushing the boat, just the jet of water is not pushing the boat directly. You could put your boat 20 feet in the air, and if you feed your jets water, the boat will move forward, turn, etc. Hell, you could put the boat in a vacuum and it would still work if you fed the jets water.
Sort of......a pump without a nozzle is just a water mover. The nozzle or "jet" in this case is what causes the boats movement. The pump itself creates a pressure differential that moves a high volume of water. Accelerating that volume of water through the jet nozzle is what creates the thrust. The water is accelerated rapidly through the nozzle due to the decrease in volume (actually integrated area) from the inlet to the outlet. Mass balance must be maintained, so in order for a high volume(mass) of water to traverse from a large opening to a small opening, it must accelerate. That ratio (in the AR190 case 155mm inlet and 85mm outlet or ~3.3:1 ratio) is what dictates the magnitude of the acceleration in the water.

Due to the equal and opposite reaction principle, we get a net result of a force on the hull, moving us forward. This is why things like the L13 cone work........This only works at high pump flows, otherwise the net force from the water acceleration is LESS than the net force from simply running a mass of water into another.....which....is why at low speeds this dynamic changes, and that is exactly what happens.

Flow rate, and given time interval greatly affect how these two principles play into one another. Slow speed is literally a "push on the nearest water" scenario, and use the pump flow to propel/move the boat around. Like what happens with a garden hose in a pool (except that wild movement has more to do with the significant lack of rigidity in the hose itself and it's inability to maintain a column shape under a light load).

A pump without a nozzle does nothing but move a bunch of water. A nozzle without a pump is just a parachute with a hole in it. The combination of the two in close proximity can create significant forward thrust.

Interestingly enough in a jet engine, because gasses are compressible, and there is combustion happening, the pumping action is actually a minor player. The expanding gasses from the combustion exit the nozzle fast enough to create thrust. Same concept as our water pump/nozzle interaction, but with an added element.

Yes and this is why things like the flyboard actually work. Notice none of the water from the jet is shooting into the water but rather the forces from the jet are pushing the rider/board.
This same concept is a great example of how the pressure differential in the pump moves the water, and the nozzle creates the thrust. The surrounding water is just acting as a big reservoir for the pump. Check out the relative sizes of the hose vs the nozzle outlets. Keep in mind every inch in diameter is worth ~3in of area (and subsequent volume per unit time)!!!

......This has been bugging me for a day now, but I think I figured out how the nozzles turn my boat even though they are out of the water. It must be the impact of the jet water stream hitting the side of the deflected nozzles like undisturbed air hitting the deflected rudder on the tail of an airplane, basically pushing it to the right or left (or not). I don't have an articulated keel with a rudder to enhance turning or fixed fins sticking down in the water. I showed Will's video to some of my staff today and they were also blown away.
You're close........Think of the nozzle as creating a "line of action" that has a force associated with it. You can use your finger and a small box on the table as an example. Push on the box (your finger is the jet nozzle and thrust) such that your finger lines up with the center of the box in all dimensions, and is perpendicular to the side you're touching. The box moves forward and in a straight line. NOW, don't move where you touched the box, but change the angle of your finger, the box will start to spin because you have now moved the line of action to direction that is no longer in line with the center of mass of the box. This induces a force moment around the center of the box, and it spins.

In rocket science there is a center of pressure and a center of thrust. So long as the center of thrust is kept behind of the center of pressure the rocket goes straight. There is a REALLY REALLY good explanation of this concept in the move "The Worlds Fastest Indian" where the main character sticks a toothpick through a cigar and blows air across it. This same concept applies to our boats, but in a smaller magnitude.

ALSO.....I found my books, but haven't dug through them yet to get you guys the cool formula's to play with :D
 
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