Physics behind the low and 

high speed

 G-Force turns  

Why is The PowerSki JetBoard™ the one and only high performance G-Force motorized surfboard, capable of out performing all the wannabes on the market?

Some of the Inventor's design notes from early 1990's explaining the physics behind the revolutionary PowerSki JetBoard invented by Bob Montgomery. These calculations included g-firce effect and unbeatable performance (great turning on low and high speed, with or without thrust)    based on fixed directional drive, hull-rail design and low center of gravity like no other craft ever invented.

The PowerSki JetBoard™

with a forward mounted engine utility patent

 There is no other motorized water craft that turns   simply on speed, thrust, weight, rail-hull design     and a balanced central placement of fuel and mechanical components such as engine, battery, fuel and exhaust. 

 What I, Robert E. Montgomery, the inventor, have researched, designed, and developed over the course of many years is a motorized surfboard  that outperforms in low and high speed turns while giving the rider more stability than all other motorized surfboards, or personalized watercraft   that have a directional, or non-directional axial flow jet pump. 

There is no other motorized surfboard, that has   this kind of horsepower, that can deliver the   proper amount of thrust for low and high speed     g-force turns, giving the rider stability based on inertia   and low center of gravity of the Patented PowerSki JetBoard


I, Robert E. Montgomery, accomplished this with a more stable, sophisticatedly designed personal watercraft with no mechanical jet drive directional nozzle. 

  This was achieved with a low center-of-gravity rail-hull design, a proper balance of weight, thrust for stability and performance to formulate or calculate a perfect (center-of-gravity pivot area point or envelope) for low, as well as    high speed maneuverability. 

The design characteristics are similar to those employed in aircraft design and, ultra-light hang gliders.

Before he takes off, an Aircraft Pilot needs to calculate the Center of Gravity (CG), a formula for weight and balance:



Before a pilot can calculate these formulas he needs to   know the manufacturer’s designated balance calculations of the empty weight of the craft, and the “Datum Line”   supplied   by the aircraft’s manufacturer.


The first steps in the Aircraft formula to find the Center of Gravity is:


  1. Empty Weight of Craft =
  2. (Gallon of Fuel) =  6 lbs. Weight of Fuel, Baggage and Passengers

100 lbs. wt locations

“Datum Line”  0    1    2    3    4    5    6    7    8    9

ARM is the distance from the measuring point or distance from datum    line

The question is does the teeter totter balance? Only if forces on the   left side are equal to forces on the right side then it will balance.

  1. 100 lbs. on the far right is more effective thanks to the weight of200 lbs. on the left side

  1. So, it is only important how much the weight is on the teeter totter, but where the weight is located, particularly, how far from the center line of the teeter totter.

  1. Center of Gravity: The point at which the entire weight of the body may be considered as concentrated so that if supported at this point, the body would remain in equilibrium in any position 

  1. Center of Mass:  The point in a body or system of bodies at which    the whole mass may be considered as concentrated.

The watercraft I, Robert E. Montgomery, designed has similar design characteristics to an aircraft or an ultra-light aircraft. From pure physics logic, it is a combination of the total mass of mechanical parts, such as   the engine, gas, battery, pump, drive train, and other parts, strategically  placed by calculating the weight balance, and the body weight of the rider can leverage his weight, and pivot the balanced and properly placed mechanical parts’ mass weight in the craft. 

The formula works with a cantilever action involving the rider’s  center of mass weight properly leveraged, or distributed on the end of the deck’s tail and by the rider leaning left or right .

Viewed from the bottom of the hull, the watercraft will pivot on the center point of gravity with ease. The watercraft invention, THE MOTORIZED WATERSKI/MOTORIZED SURFBOARD, PowerSki JetBoard™, was   not achieved without many years of research, testing, and development    to find and calculate the envelope of the center balance of the  pivoting point,or area, to turn this craft correctly at high and low   speeds. 

The center of gravity’s sweet point in my   motorized surfboard design, or area in aircraft terminology, is called the C.G. ENVELOPE. 

In order to fly the plane balanced for a safe flight, before takeoff, the pilot needs to calculate the proper Center of Gravity because with the added weight of the passengers, baggage and gas the C.G. might move out of the C.G. envelope

I, Robert E. Montgomery, designed a watercraft with a bottom hull  and rail shape that has a specific area, or envelope, of proper placement of balance of the mechanical parts’ mass weight, and the physical placement of the rider’s body weight to create necessary leverage for a perfect, cantilevered, center-of-gravity pivot point for low and high speed turns that are smooth and stable for the watercraft rider without the use of a mechanical swivel, or   directional jet-drive nozzle.

From a physics standpoint, the watercraft I, Robert E. Montgomery, designed, a novice rider’s    coordination is optional.  

Designed with a low center of gravity, the rider stands on the craft’s deck area just behind the central pivot point, or center of gravity, toward the center of the rear hull bottom of the craft.  The rear of the craft and the  rider remain stationary and the front of the craft moves left or right.

One of the first of several forces that play a major part in any design is a designed low center of gravity rider deck area coupled with a hyper-parabolic (curved) rail and bottom hull shape.

BELOW: First time rider, novice taking off on the Patented PowerSki JetBoard
BELOW: First time rider's coordination is optional. As you can see she makes her first turn slow and easy by simply leaning slightly to the left

The designed low center-of-gravity riding deck gives the rider stability    and a better sense of balance, because the rider is closer to the water surface, and the hyper-parabolic or curved rail and bottom hull shape,     are designed for several important reasons. First, to add stability with a  low C.G., if the novice rider unintentionally leans left or right on a take    off, he, or she, will simply glide into a turn. There is no abrupt, unstable, side-to-side tipping, or unstable sliding of the craft’s tail area that could throw the rider side-to-side.  The curved rail, coupled with a low C.G.     and central pivot point,  won’t allow any abrupt movement other than a    smooth gliding turn.

BELOW: Chad Montgomery makes a high speed g-force turn on the Patented PowerSki JetBoard. Rider cannot pull this kind of G-Force turn with his/her body laying  flat inches above the water without my patented designs which include, the proper horse power, thrust, Center of Gravity Design and my monolithic hull-rail design.
The second reason for the hyper-parabolic rail and    curve shaped bottom and rocker of the PowerSki JetBoard™ hull is to insure that when the rider leans at low and high speeds, the craft’s proper angle, or turn direction will be instantly set without the need for a mechanical jet drive directional nozzle attachment.
I, Robert E. Montgomery, designed the hull bottom of   the PowerSki JetBoard™ to give a rider multiple   choices. The first choice is the stable, no-rocker straight, flat area coupled with the balanced placement of mechanical parts and fuel weight.  This stable no-rocker straight flat area is located at the rear-hull bottom tail section that gives the rider a takeoff free from   porpoising, or rocking.

The jet pump thrusting the craft forward, causing a fast, forward   movement creates this. This flat stabilizing area, coupled with the center   of gravity area, resists the porpoising, and stabilizes the craft without       the rider leaning his weight forward to help compensate for the take-off    inertia of the watercraft/surfboard.

BELOW:  First time rider taking off with inertia   showing how the bottom of the hull design stabilizes the novice rider.

BELOW: First rider stable ride, going full speed    without purposing because of the bottom hull design    and placement of  riders feet and weight for proper Center of Gravity

This very important stable flat area, without any rocker or curve, is approximately 6-10 inches wide inline, and flat with the overall bottom    hull depth and center of the craft.

The next choice from the bottom area a rider can make is the V bottom located on both sides of the stable bottom flat area flowing into the entire bottom hull rail area. For more leverage, this V area increases in     degrees of angle toward the tail section area, and this angles the   watercraft to set the course direction or turn for the watercraft, the PowerSki JetBoard™, that I, Robert E. Montgomery, designed.

The next area of the designed shape incorporated in the overall bottom  hull side and the V area extending from the nose to the tail is called the overall rail section rocker. This curve plays an important part of the     rider’s directional angle, and determines how tight or fast the watercraft   will respond by allowing the set angle by leveraged moves of the rider’s properly placed center of mass weight that first responded to the stable   flat area, then to the V area to the overall rail section rocker area of the PowerSki JetBoard™ hull.

 The last choice, but one of the most important design    shape features in this monolithic hyper-parabolic overall bottom hull rail shaped watercraft is the curve shape of the rails of the PowerSki JetBoard™’s hull.  The PowerSki    JetBoard™’s curved-shaped rail, using proper body weight leverage, will set the watercraft’s direction, or angle, in a turn.  When the craft is in a slow or high-speed turn, it actually glides on this curved rail’s edge with the water overlapping.  With an increase in water depth, starting at    the tip of the watercraft’s tail section rail edge, and a decrease in the overlapping water towards the mid-rail    edge, or the watercraft’s engine compartment rail edge   area, depends on the speed and proper placement of the   body center of mass weight and proper balance of the mass weight of mechanical parts placement. This final curve surface rail line is similar to a curve in a high-speed motorcycle tire. When they turn, they depend on the curve surface of the tire to set and hold the final angle, or   direction of a turn.

I, Robert E. Montgomery, will explain the performance characteristic of a Jet Ski or any other personalized sit-down, or standup watercraft with a mechanical directional nozzle attached to an axial flow jet drive pump, used to make the watercraft turn left and right.

BELOW: demonstration on high thrust out of the non-directional JetPump Nozzle. Nose of  Patented PowerSki JetBoard is setup against to keep the board in stand still position to demonstrate the high thrust at full throttle.

I, Robert E. Montgomery, will explain the performance characteristic of a Jet Ski or any other personalized sit-down, or standup   watercraft with a mechanical directional nozzle attached to an axial flow jet drive pump, used to make the watercraft turn left and right.

There are rules that govern how machines make motion.  First, from a physics stand point, one of the basic laws is inertia, and it goes like this: a body at rest tends to remain    at rest, and a body in motion will tend to stay in motion in    a straight line. To change either of these conditions, you have to provide an outside force, like the power of the  engine making thrust out of the back end of the pump. 

Watercraft with mechanical directional nozzles turn with  this outside force called vector thrust, which turn the   pump.  When the pump nozzle is turned, most of the force    is still directed backwards, but a significant part is not pushing sideways. To turn left, the pump is turned towards the left, so you would logically think that the watercraft would be pushed to the right. 

But we fail to take into account the center of gravity of the watercraft, which is placed by the pump’s direction toward the front of the watercraft or boat.  The C.G. is the point 
upon which inertia acts on the watercraft, it’s the balance point for all the directions around which the craft wants to rotate.  If we force water to the left, the watercraft rotates 
its rear to the right, and the nose to the left.  The angles 
don’t lie.  Even large boats use jetivators that improve 
angles of the pump thrust to move the pivot point closer to the tail of large heavy jet drive boats, but it doesn’t change the pivot point very much to enable the heavy boat to turn 
in slow or high speeds.
Going back to the physics view point: a personal watercraft rider turns his pump nozzle to direct his vectored thrust to rotate the far forward center of gravity, which moves his body side to side, wasting kinetic energy and removing his sense of balance or stability.

This serious stability problem is similar to three wheel all-terrain vehicle accidents, which lead to the deaths of many riders because dirt or streets are not as forgiving as water.  This is a very serious problem because of the standup Jet Ski’s instability for novice riders, and has resulted in a loss
 of sales for standup Jet Ski watercraft.

Larger watercraft have increased their sales, which speaks 
for itself about a desire for a more stable, user-friendly watercraft.  Although the large sit-down watercraft have a forward central pivot point, causing the rider’s body to 
move from side to side, he or she can better handle these unstable slide turns because the rider is sitting down 
creating a lower center of gravity, and do well in low and high speed performance turns.

Stand-up Jet Skis and large sit-down watercraft, have a very high C.G., off the water surface while riding, or the higher the C.G. of the craft off the water surface the more unstable the craft becomes.

Stand-up Jet Ski hulls are designed with vertical slide rail walls.  A novice rider has no control if he leans without 
using his directional nozzle to turn. The high C.G. results
in the rider being thrown off the craft. A Jet Ski won’t turn without using a directional nozzle.

From a physics standpoint, the watercraft I, Robert E. Montgomery, designed, a Motorized-Water-Ski/Surfboard, the PowerSki JetBoard™, the rider stands over the central pivoting point at the rear of the craft, and the entire front 
of the craft pivots. The rear of the craft and the rider, jetboarder, remain stationary, and the front of the PowerSki JetBoard™ moves  left or right.
This superior, high performance, stand-up personalized watercraft, the PowerSki JetBoard™, that I, Robert E. Montgomery, designed, outperforms the Jet Ski in stability and in low and high speed turns by pure physics logic with    a monolithic integrated combination of calculated forces working together.

One of the first of several important forces that plays a part  in my design is a low-center of gravity coupled with a  hyper-parabolic rail and hull design.

In designing this watercraft, the PowerSki JetBoard™, I    had to overcome problems, such as deep water mounting, which causes the craft to take water into the interior hull compartment.  This occurs because of the PowerSki JetBoard™’s low C.G. design, coupled with its hyper-parabolic rail and hull design, which is necessary for  stability and turning performance.  This problem had to be solved, without changing the shape of the craft.  

For example, for a deep-water mount, a rider weighing 150 lbs., or more, swims to the Jetboard’s deck tail and assumes  a prone position for take off.  The watercraft’s weight is,     or will be 85-150lbs.  Its easy to understand the magnitude   of this particular problem to keep water sealed out.

Then there were the mechanical weight problems to    achieve proper balance of this unique watercraft that   related to the need for balancing for the proper    performance of low profile watercraft The PowerSki JetBoard™.

In the late 1980s, the first prototype of the PowerSki JetBoard™ I designed was very small, from 0.5” thick in   the rear deck area to 10” in engine compartment area in height and thickness, 7’ 8” in length and from 14” wide at  the tail to 26” wide at the engine compartment, it’s widest point.

Below: Bob Montgomery's Patented PowerSki Jetboard Prototype
Below: Bob Montgomery's with his early Patented PowerSki Jetboard Prototype

BELOW: Bob Montgomery (in the middle) showing his internal aluminum frame that was place into the board

BELOW: Bob Montgomery's internal fram mounted into the Patented PowerSki JetBoard Prototype

BELOW: Bob Montgomery showing his design of the pump installation, along with other components into the Patented PowerSki JetBoard Prototype

BELOW: 15hp engine used by Bob Montgomery for his 1st prototype of the PowerSki JetBoard. Please note the aluminum lid with the large area with an O-ring gasket, which was impossible to seal. Submerging the deck of  the first prototype would cause enormous water intrusion which impossible for production.

BELOW: Bob Montgomery, the inventor, making his first on his 15hp Patented PowerSki Jetboard Prototype in the late 1980's, as seen above. This early prototype was lacking horsepower and did not give Bob enough power to pull off a true, fully extended high speed g-force lay down turn as you can see on the picture.
To achieve a low profile or low C.G. design for increased stability and performance, I mounted a 15 hp outboard,    two-stroke, water-cooled engine horizontally, or sideways   to reduce the height. The marine outboard, two stroke,  water-cooled engines are mounted in an upright position    for an outboard prop, or jet drive application.  In designing my low profile watercraft, the PowerSki JetBoard™, I, Robert E. Montgomery, had to overcome problems, such     as proper balance of the engine and the other mechanical parts. 

The outboard engine is mounted sideways with the  carburetor and 2 cylinders on the right.  This put most of   the engine’s weight on the left side of the watercraft. To solve this improper balance problem in this early prototype of the PowerSki JetBoard™, I, Robert E. Montgomery, inserted and mounted and long-grated gas tank in the right rear section of the watercraft for proper balance.  The fuel weight on the right, facing the nose of the watercraft, offset the engine cylinder weight on the left hand side.
Below: Bob Montgomery's Patented PowerSki Jetboard Prototype
Sealing the first prototype was relative to the installation   and accessibility of the parts in the tail section of the board.  These included the gas tank and the exhaust, along with    the connecting water intake and water exit lines, the driveshaft couplers, the bearings connected to a jet drive pump, all connecting to the engine mounted 46.5” forward from the tail.  Performance, reliability, and mechanical installation of the above parts were also key.

The solution I, Robert E. Montgomery, the inventor,    devised was a large rear O-ring sealed lid that completely opened up the rear tail section for parts installation and accessibility in this early PowerSki JetBoard™ prototype.    It is 29“ from the tail, and approximately the same length   as the gas tank exhaust, and driveshaft (late 1980’s).

After months of riding and testing my first PowerSki JetBoard™ prototype, I, Robert E. Montgomery,    discovered that the large O-ring sealed lid, made from and supported with aluminum framing and overlaid with fiberglass in a box-like structure, started to fatigue the     large seal and allow water to leak into the internal hull compartment.  This was caused by the rider’s (jetboarder) standing, jumping and shifting his weight to maneuver the craft at speeds of 25 to 27 mph.  I repaired the seal and    tried to eliminate the problem with unsatisfactory results. Too much water leaking into the PowerSki JetBoard™ prototype reduced performance because of the additional water weight.

The bottom line was that the PowerSki JetBoard™ would  not be reliable enough for a company to give it a standard consumer warranty without major hull replacement  problems resulting in lost profits for the patent owners, the HydroForce Group, LLC.

Realizing these major problems had to be resolved, I    started redesigning the entire watercraft, PROTOTYPE #2.  This time, I chose a 25 hp engine to overcome the 15 hp engine’s insufficient power to compete in performance and sales in today’s personal watercraft market. 

At that time, I estimated this new design with a 25 hp   engine would have enough power to compete with Jet Skis’ speed of 35 to 50 mph. At that time, the average successful speed of a personalized watercraft was approximately        35-45 mph.

Because of the importance of a user-friendly deep-water mount, addressing the problem of sealing these early PowerSki JetBoard™ prototypes was vital to insure    stability a Jetboard rider needed.

The watercraft weighs 140 to150 lbs. (dry weight). The tail width was 15.5”, and the mid-section area was 27” at its widest point because of the engine’s width and placement.  Any wider, and the turning or maneuvering performance drops considerably. When the average Jetboard rider, weighing 140 to 220 lbs., mounts the PowerSki JetBoard™ from the rear or tail, the entire tail section will be   submerged producing water pressure on any sealed area.

Understanding this problem, I changed my design for installing the drive shaft, gas tank and exhaust chamber,  from the large rear O-ring deck area that opened up for access to the drive shaft, bearing, and exhaust chamber.    The new design allows easy installation.

For the aforementioned mechanical parts to be installed   from the engine compartment into their proper position inside the tail section, I redesigned the engine     compartment with a hood large enough to accommodate a long-range gas tank, an exhaust pipe and drive shaft, both approximately 32” in length.

The PowerSki JetBoard™ prototype #2, I, Robert E. Montgomery, designed, was still insufficient to completely solve this major mechanical problem. There was still a    need to access the inside of the tail at the back wall of the exhaust and gas tank compartment. 

This access was needed to allow for fittings, hose clamps, exhaust mounts, water intake engine cooling hoses that   come from the outside bottom hull pump compartment and pump hoses.

All of these fittings for hoses, exhaust bilge pump, and   water drainage had to be connected to mechanical components through the pump housing walls on both sides inside the hull exhaust compartment. 

Because of the required length of the gas tank, drive shaft, and exhaust chamber, clamping these necessary     mechanical components could not be done from the engine compartment.  I had to design two small hand access     O-ring deck plates for connecting these needed mechanical components. 

The deck plates’ size only needed to be large enough to accommodate someone’s hand, or hands, and tools for properly clamping these components. This design moves    the installation of these components from the engine compartment, and by connecting them together through   these small, hand-accessible, O-ring deck plates,    completely solved this extreme water pressure  intake-sealing problem.

The new design allows a Jetboard rider to stand and jump    on the rear deck area without damaging these small O-ring deck plates.  The small size of these hand-access O-ring  deck plates, coupled with a structural redesign of the     inside of the enclosed walls of the exhaust, drive shaft, and gas tank watertight compartments, produces a structurally solid product for warranty.

In addition to the tail deck area sealing problem, during  high-speed performance or deep water mounting of the watercraft, the engine compartment top deck hood seal   could not be submerged under water. This problem occurs because of the watercraft’s low profile design, and  depending on the size or weight of the Jetboard rider, becomes a more serious problem, compounded by the   length reduction of the PowerSki JetBoard™ prototype #2.

The water pressure against the large engine compartment deck seal presented a very difficult problem. The solution was to incorporate four hood latches (Fig. #24, 25, 26 and 27).  In the next PowerSki JetBoard™ prototype, that I, Robert E. Montgomery, designed, I replaced the large neoprene gasket with a large rubber inflatable O-ring    gasket (Fig. #28).  This is used in the current production model of the PowerSki JetBoard™.  This new inflatable O-ring prevents almost any water leaking into the watercraft.

The watercraft’s low profile design creates still one more major problem. The small gas engines, currently available   in today’s market, that are suitable for this application, are  25 to 30 hp two-stroke twin cylinder water-cooled engines. All of these engines have open flywheels that are not enclosed and watertight. The open flywheel engine,   mounted on its side, is normally used in upright outboards with a splash proof cover.

The same engine, mounted on it’s side, places the   flywheel’s spinning edge at the very bottom of the watercraft’s low profile hull.  There is no other way to  mount this engine, to achieve the design and performance that I, Robert E. Montgomery, have described previously. Today’s (early 1990s) two-stroke, water-cooled 25 to 30 hp engines do not have the power needed to satisfy consumers (jetboarders), or compete with other successful watercraft speeds. 

Running with power, this engine, mounted sideways, has a small amount of water splashing around in the engine compartment.  When that water hits the exposed spinning flywheel, it throws a condensation of water throughout the engine compartment. The engine carburetor immediately sucks this water up, like a vacuum cleaner, into the engine causing serious performance problems, including, from    time to time, stopping the engine from running all    together.

The engine rubber/metal mounts are structurally fitted to   the monolithic contoured structural walls on both sides of  the entire internal mechanical compartment. This design displaces all engine, riding, and jumping vibrations, or shocks to the hull through the four rubber mounts.    (Fig. #31- #34)

The engine mounted to the back wall of the internal compartment is connected by a short drove shaft (Fig. #35) with a coupler (Fig. #36). The coupler is connected by a  short drive shaft (Fig. #35) with a coupler (Fig. #36). The coupler is connected to another coupler (Fig. #37) with a rubber damper (Fig. #38), between the couplers. The other coupler is connected to a longer drive shaft (Fig. #39) that    is supported and housed in a forward bearing housing  (Fig. #40) that is mounted to a forward composite bulkhead face plate (Fig. #41) that’s approximately 4” in width.

The drive shaft is housed in a tube (Fig. #42) that is housed by a square design drive shaft composite structure compartment (Fig. #42). This drive shaft composite   structure was designed for overall hull, top deck, and drive shaft supported strength, which is greatly needed, because   of the torque on the drive shaft bulkhead support. The    shape also allowed for space on both on both sides of the drive shaft compartment, for two internal components, gas and exhaust.

The drive shaft is connected to an axial flow                     non-directional jet drive pump (Fig. #48). The pump (Fig. #48) is mounted up inside the pump compartment    (Fig. #49) with four bolts (Fig. #50). The pump water intake   scoop and safety guard (Fig. #51) is mounted flush to the bottom of the hull in front of the pump. The pump and ride plate (Fig. #52) are also mounted flush to the bottom of the hull for perfect water flow. 

The new internal design structure of this fiberglass  composite hull was very important for the PowerSki JetBoard™’s hull strength, as well as the mechanical placement for balance which results in center of gravity pivoting area of performance. The outlining internal    vertical walls were designed for structural strength and mechanical placement for balance and performance.

Now to address the structure strength, which relates to the outlining internal contoured vertical walls, which relates to the overflowing inside and outside vertical walls which relates to the overall designed interior and exterior shape     of the PowerSki JetBoard™ hull. These structural vertical walls start with bottom hull pump compartment vertical   walls tail section and interlock with the interior vertical walls, which overflow to the outside contour shape walls continuing forward to the nose of the PowerSki   JetBoard™’s hull which gives very important longitudinal strength to this high-performance, low-profile watercraft.

I, Robert E. Montgomery, designed this uniquely hollow   hull shape, with the necessary space for mechanical parts.  The size, in regards to weight, height and width, is also necessary for stability, maneuverability, and performance that will satisfy the highest expectations of   riders/jetboarders around the world.

With all the mechanical vibrations, mechanical weight, rider’s weight, constant impact from choppy water, and    high aerial jumps performed by jetboarders, without my hollow hull design, the PowerSki JetBoard™ would not   hold up structurally. This PowerSki JetBoard™ hull was designed with a one-year warranty in mind against both smooth and rough JetBoarding use.

Now, I will describe the important structural composite multi-design shape, starting with the exterior bottom hull pump-housing compartment (Fig. #49).  The continual structural monolithic contoured walls start with both sides   of the pump housing walls (Fig. #1 and Fig. #2).  The  interior of the PowerSki JetBoard™ hull’s tail section of   the pump housing compartment bulkhead wall (Fig. #3), starts wrapping left and continues forward down the     interior exhaust compartment wall (Fig. #4) towards the   front of the PowerSki JetBoard™’s hull.

The vertical contour walls of the drive shaft’s enclosed watertight housing, and enclosed compartment is     connected by a tube to house and support the drive shaft  (Fig. #5)   inside the pump housing compartment     (Fig. #49) in the tail section in the hull bottom. This wall then wraps around to the drive shaft’s bulkhead support wall    face (Fig. #6). This wall (Fig. #6) is 4” in width. This contour wall takes a sharp wrap to the right, again entering into the gas tank compartment (Fig. #7), then all continue    to the rear of the gas tank compartment.  

This contour wall continues into a sharp left bend (Fig. #8). This wall width can change according to the width of the watercraft’s tail area, which can change from point to    point. This can increase, or decrease the gas tank’s size.  This wall bends to the left (Fig. #9) and continues forward  for approximately 10” to the A vertical-slated motor    mount wall (Fig. #10) wrapping left approximately 2.5”  then right approximately 6.5” then wrapping right again 1.5”. This contoured vertical wall wraps sharp left   (Fig. #11) and continues to the next motor mount (Fig. #12), a square vertical shape, approximate height 2”, then bends   left 2.75”, then bends right for approximately 5.75”, and  then bends right again for approximately 2.5”. 

This contoured vertical wall continues then bends left (Fig. #13) and continues at a slight left angle for approximately 5.5”. This wall continues until it comes to the watertight bilge pump compartment wall (Fig. #14).

This wall continues then bends sharply left for  approximately 1”. This contour wall continues into a sharp right bend (Fig #15) and continues for approximately 8.5”, which can change from point to point. This wall continues then bends right (Fig. #16) for approximately 16.75”.  The fire extinguisher compartment at the bottom houses the  cable and wire hose (Fig. #17), and the air tubes (Fig. #18) passageway.  This wall then bends sharp left at the very top of the hull’s nose section (Fig. #19) for approximately 4”.

This wall continues then bends sharply left and continues    its flow matching the opposite wall. I, Robert E. Montgomery, just described all of the ways back to the tail section of the exhaust compartment.  Made of fiberglass composite, this entire interior compartment design   continues vertically with contour walls that flow up and   over on to the exterior PowerSki JetBoard™ prototype   hull’s contoured rails that I, Robert E. Montgomery,  designed and developed.

This shape design that I described, gives the PowerSki JetBoard™ hull strength that guarantees this mechanical high-performance watercraft, the PowerSki JetBoard™, to  be warranted for many years with no stress, fatigue and breakage problems.

In order to understand the magnitude of this contoured longitudinal and lateral strength, I need to explain my moldings’ design. This process consists of three main   molds: the bottom mold, interior mold and the top deck mold. 

The bottom mold forms the pump housing compartment,   and the entire bottom shape, from tail to nose and halfway  up the entire contoured rail at a part line.  The interior    mold forms the entire engine and mechanical   compartments I previously described. The contoured compartments are outlined with a continuous vertically contoured overflowing wall that rises up and over onto the outside contoured shaped rails that meet halfway down the rail to the bottom mold.

The interior and bottom walls give longitudinal strength to the entire hollow hull. The bottom and interior molds are injected, or poured, with closed cell foam and clamped together with the interior flange mold until cured.  The top deck mold produces the entire contoured deck and half of  the rail, minus the engine compartment hood.  The top    deck mold is glued together with resin, or a putty of    choice, and clamped with the bottom mold. The molds are opened after the parts are cured.  The top deck part and the interior form one part and match at the same parting line. The bottom part is matched at this parting line, which produces a finished monolithic, lateral and longitudinal structurally solid product.

The combined contoured composite shaped top deck,  interior and bottom seals the entire PowerSki JetBoard™ from any water entering the hull foam, and gives superior flotation and strength to the PowerSki JetBoard™ more    than any other motorized, personalized watercraft ever built.  This sophisticated, light, composite-shaped product and mold design not only allows for a warranted product  with incredible strength factors, but also allows the watercraft to be assembled faster that most motorized,    high-performance personal watercraft being produced   today, such as Jet Skis or other sit down watercraft.

This is because assembly consists only of taping, drilling holes and inserting screw-in parts. In fiberglass manufacturing, most assembly lines for Jet Skis and other   sit down watercraft assembly consists of gluing together top deck, hull bottom and bulkhead compartment walls, and adding and gluing the foam.

The strength factor of these other fiberglass watercraft fabricated with only one vertical fiberglass wall that stands alone without reinforcement of a fiberglass composite foam sandwich. Their hulls don’t compare to my PowerSki JetBoard™’s hull design of a Triple Continuous Vertical Overlapping Monolithic Contour Interlocking Composite Fiberglass Hull.

This design compares to having 3 L Beam Stringers     running on both sides of the hull from the tail to the nose     of the craft. (Drawing must show composite lay-up).

For example, as described in (Fig. #20), the outer hull described in (Fig. #21), the hull interior, described in (Fig. #22), the hull top deck, described in (Fig. #23), interlocking seam, and finally, as described in (Fig #24) the injected, or poured closed cell foam.   

The battery, inside the battery box, is placed in front of the engine compartment (Fig. #25).  The water bilge compartment (Fig #26) is located in front of the battery.    The water bilge pump and O-ring face plate (Fig. #27) are bolted down inside this water-trapping compartment. The   O-ring face plate (Fig. #28) is screwed into the water bilge compartment bulk head wall (Fig. #14).

The O-ring face plate releases air and seals out water from entering into the other compartments. When water gets past the good air intake system in the watercraft’s nose hits the small bilge pump water sensor, its immediately sucked up and out of the watercraft through the bilge pump hose (Fig. #29) and exit nozzle (Fig. #30).  The fire extinguisher compartment (Fig. #31) is located in front of the water    bilge pump compartment (Fig. #26). 

This extinguisher compartment is a housing for a finished  fire extinguisher box (Fig. #32) with a watertight lid and is glued into this channel, or fire extinguisher compartment (Fig. #31) that leaves space at the bottom of the  compartment (Fig #31) for air (Fig. #32), the steering cable (Fig. #33), and the wiring for the air intake (Fig #35), the  arm pole assembly (Fig. #36), and the handle (Fig. #37), to run under the fire extinguisher box (Fig. #32) from the watercraft’s nose.

When a Jetboarder pulls on the attached operations handle (Fig. #37) the arm pole assembly (Fig. #36), a flexible hose,  0 won’t stretch because of the important enclosed wiring harness. I, Robert E. Montgomery, designed the handle     (Fig. #37).  The rider’s speed is controlled by the handle’s throttle lever that the rider pushes down to increase speed (Fig. #38).  This thumb leverage is natural because of the inertia caused by the engine making thrust out of the pump that creates the watercraft’s forward speed.

The handle design allows the Jetboarder, in a low or high-speed turn, to maneuver the watercraft properly by leaning his body weight from side to side. With his fingers   squeezing the handle base grip (Fig. #39) as tightly as desired, the rider can pull back as hard as he wants while controlling the proper speed by pushing the lever or button throttle control (Fig #38) up or down. This safety design feature solved a major problem that exists today in most other types of personalized watercraft.

The throttle handle that I designed also has    thumb-activated buttons for starting (Fig. #40), and engine shut off (Fig. #41).  The handle design has one more safety feature,  an engine kill or automatic stop switch (Fig. #42) located    at the base of the handle.  This engine kill switch is    attached to the rider’s required life vest with a tether cord that plugs into the handle base. The engine automatically shuts off when a Jetboarder dismounts the PowerSki JetBoard™ at low or high speed.  Without this design safety feature the liability insurance for the PowerSki JetBoard™ would be too costly to manufacture.

The safety nose piece (Fig. #43) was designed with two features in mind. The first was safety, which relates to impact, which relates to sore thickness and weight. The second was strength, which was how to attach a thick and heavy enough rubber or silicone part to the nose resist a  high-speed impact.  The product in design had to be warrantable, therefore, a need to replace a safety inset   piece, with easy maintenance had to be designed.  An adhesive attachment didn’t work because of the nose piece’s size and weight.  This application would not hold up to being warranted under normal use.  It would likely be damaged in a high-speed impact with a solid object.  I solved these problems by designing a rubber nose piece that would hold up under normal use, and could be replaced or attached without adhesives.  It also was warrantable.

The nose piece attaches and locks into the watercraft’s nose with a small solid rubber bean extension (Fig. #44)  projecting out of the back of the nose piece. The design works like an off-road trailer sleeve on a car or track.  The sleeve supports the weight of the trailer by sliding a smaller square steel support beam from the swivel type extension, that is attached to the trailer tongue into a larger extension beam (Fig. #44) that supports the proper weight and correct size of the front section of the rubber nose piece (Fig. #45). 

For added support and strength, the nose piece was  contoured to match and slightly overlap the JetBoard™’s designed fiberglass0shaped nose. The nose piece’s solid extension beam (Fig. #44) slides into a design-shaped (Fig #46) housing, and is attached, with or without the use of silicone or adhesives, and properly secured in place by drilling and tapping two small screws (Fig. #47) on the fiberglass deck top.

The two screws are drilled and tapped into the rubber nose piece extension beam (Fig. #44).  The rubber nose piece   (Fig #43) is molded with a small piece of metal, or insert, placed in the center of the nose piece’s extension beam for tapping and drilling.

The safety rubber nose piece is an important design feature for this PowerSki JetBoard™ hull design I, Robert E. Montgomery, invented, because all other personalized watercraft have rubber bumpers attached to their external flange. The external flanges molding process they use attaches their top decks and lower hull bottoms together.

The PowerSki JetBoard™ I, Robert E. Montgomery, designed has proper water flow, a low center of gravity, hyper-parabolic contoured rails, and a perfectly matched    top and bottom internal flanged hull without a visible     seam for proper performance and maneuvering.  The PowerSki JetBoard™ would not turn, or perform properly without a bottom and interior hull sealed by an exterior flange   molding process.

Bob Montgomery, Inventor of the Patented PowerSki JetBoard and Engine Technology