Abstract:
A personal watercraft having improved bottom hull shapes in general, and improved center keel shapes in particular. The center keel can have a substantial section over which the keel angle becomes sharper progressing from front to rear, and the concavities on either side of the center keel become deeper progressing from front to rear. The center keel can have a point of maximum downward slope on either side of the keel centerline, with the maximum vertically downward slope becoming greater with greater rearward distance over a section of the personal water craft bottom hull. The bottom hull can have keel troughs on either side of the keel centerline that become deeper over a section of the personal watercraft bottom hull, traveling from front to rear over that selected section of personal watercraft bottom hull. The center keel shape can provide a smoother ride and improved handling in rough water. When the bottom hull is in the water, the sharper keel angle and deeper troughs leading to the transition region and the tunnel of the watercraft can more effectively channel water to the tunnel and to the jet pump.

Description:
FIELD OF THE INVENTION 
   The present invention is related generally to personal watercraft. More specifically, the present invention is related to personal watercraft hull and keel shapes. 
   BACKGROUND OF THE INVENTION 
   Personal watercraft hull designs typically have a center keel shape that remains essentially constant over the length of the watercraft, or transitions to a flatter, shallower keel shape as the tunnel to the rear of the watercraft is approached. Some personal watercraft have substantially rounded, shallow-angled, or even flat center regions, disposed between longitudinal chines running along the underside of the personal watercraft. The conventional design has proved adequate in the past in general, but applicants suspected that the conventional hull design could be changed to improve personal watercraft handling in rough water. 
   SUMMARY OF THE INVENTION 
   The present invention provides a section of a personal watercraft center keel that has unique geometry. In the front of this section, the keel can be wider, providing more lift, and riding high on the water. The keel can have a shallow concave trough on either side. In the rear region of this selected section, the keel can be narrower, providing less lift, and cutting deeper down into the water. The keel can also have deeper concavities on either side, forming steeper angles on either side of the center keel. The trough depth on either side of the keel centerline can get progressively deeper progressing rearward in the watercraft over this selected section. 
   The present invention provides a personal watercraft including a bottom hull including a center keel having a keel surface and a centerline. The center keel can have a longitudinal portion disposed between a front point and a rear point. The keel portion between these points can have a keel angle that is smaller at the rear than at the front. This selected keel portion can be disposed within the middle third of the watercraft in some embodiments. The keel angle may be defined in some embodiments for each location along the centerline. The defined keel angle can be defined as the angle formed between the keel bottom surface at the centerline and two keel bottom surface locations which are disposed transversely away from the centerline at a location of greatest downward slope on the keel surface. In some embodiments, the selected keel portion rear point is located about 1½ feet forward of the jet pump. The selected section can extend about 4½ feet forward of the rear point. 
   The present invention also includes a personal watercraft hull comprising a center keel portion on the hull having a surface, a length, and a plurality of locations along the keel length through which a transverse cross-section can be taken through the keel. The transverse cross-section has a point of greatest downward slope taken at the surface on each side of the keel where the surface has the greatest downward slope. There exists a keel section having a length over which the greatest downward slope increases from front to rear over the section length. In some embodiments, such a keel section is found within the middle third of the personal watercraft along its length. The center keel portion can be integrally formed with the hull. In some embodiments, the keel section begins about two feet forward of the jet pump and extends forward for about four feet over the length of the section. In one embodiment, the center keel maximum vertical downward slope is greater at a location four feet from the rear-most extent of the watercraft than at a location three feet to the rear of the front-most extent of the watercraft. 
   The present invention includes a personal watercraft hull having a center keel portion having a surface, a length, and a plurality of locations along the keel length through which a transverse cross-section can be taken through the hull. The keel can have a trough having a trough depth on each side of the keel. There exists a keel section having a length over which the trough depth increases from front to rear over the section length. In some embodiments, such a keel section is found within about the middle third of the personal watercraft length. In some embodiments, the keel section has a length of between about three and five feet and lies within the middle third of the personal watercraft length. In some embodiments, the trough depth is measured as a normal distance from a trough boundary to the hull surface in the trough. In other embodiments, the trough depth is measured as a vertical distance from a midpoint of a trough boundary to the hull surface. In some personal watercraft, the trough depth at a location four feet forward of the rear-most extent of the watercraft is greater than a trough depth located three feet to the rear of the forward most extent of the watercraft. 
   In previous watercraft, the center keel often started out having a sharp angle at the front of the watercraft, flattening to have a much shallower angle as the tunnel was approached. Applicants were surprised to find that the center keel shape of the present invention increases the lateral resistance to movement and improves stability in the water when cornering. The present invention provides smoother operation of a personal watercraft while allowing for more predictable maneuvering. 

   
     DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a side, cut-away view of a personal watercraft; 
       FIG. 2  is a bottom, perspective view of the personal watercraft of  FIG. 1  having a center keel that begins with a shallow angle having shallow troughs on either side, proceeding rearward to have a sharper keel angle with deeper troughs; 
       FIG. 3  is a bottom view of the hull of  FIG. 2 ; 
       FIG. 4  is a fragmentary view of a personal watercraft bottom hull taken about either side of the personal watercraft centerline, from a front extent, to a rear extent, showing view lines  5  through  10 , corresponding to  FIGS. 5 through 10 ; 
       FIGS. 5 through 10  are fragmentary, transverse, forward-looking cross-sectional views taken through view lines  5  through  10  of  FIG. 4 , respectively; and 
       FIG. 11  is a side view of a personal watercraft bottom hull, having view lines  12  through  22 , corresponding to  FIGS. 12A and 12B  through  FIGS. 22A and 22B , respectively; and 
       FIGS. 12A through 22B  are transverse, forward looking, cross-sectional views taken through view lines  12  through  22 , respectively. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The following detailed description should be read with reference to the drawings, in which like elements in different drawings are numbered identically. The drawings depict selected embodiments and are not intended to limit the scope of the invention. Several forms of invention will be shown and described, and other forms will now be apparent to those skilled in art. It will be understood that the embodiments shown in the drawings and described below are merely for illustrative purposes, and are not intended to limit the scope of the invention as defined in the claims that follow. 
     FIG. 1  illustrates a personal watercraft  20  having generally a front or bow  22  and a rear or stern  23 . Personal watercraft  20  includes a top deck  26  secured to a bottom hull  24  along an overlapping portion covered with a rub rail  32  in the embodiment illustrated, forming a hull. A hood  37  may also be seen, joined to top deck  26  at a hinged front hood portion  36 . The hull formed by the bottom hull  24  and top deck  26  define a compartment sized to contain an internal combustion engine  33  for powering the watercraft, and may also include one or more storage compartments, depending upon the size and configuration of the watercraft. The deck portion  26  also has a raised, longitudinally extending seat  28  adapted to accommodate one or more riders seated in straddle fashion on the seat  28 . A grab handle  38  is disposed transversely across the rear of the seat. Engine  33  powers a jet propulsion unit  34 , typically mounted in a tunnel at the bottom rear portion of the watercraft, all shown in phantom in  FIG. 1 . Jet propulsion unit  34  includes a steerable water discharge nozzle  29  that is operatively connected to a set of handlebars  42  to facilitate steering of the watercraft by the operator. Handlebars  42  typically mount through a top portion of a shroud  40 . The connection between handlebars  42  and discharge nozzle  29  may be of any suitable type, and typically includes mechanical linkages including a control cable. If desired, an electronic connection could also be utilized. 
     FIG. 2  illustrates bottom hull  24  of  FIG. 1  in a perspective, bottom view. Hull  24  extends generally between a front-most extent  50  and a rear-most extent  52 . Hull  24  includes a centerline  58 . A center keel  80  may be seen having a trough  81  on either side in some regions. Keel  80  has a front region  66 , an intermediate region  68 , a rear region  70 , and a transition region  72  in which the keel transitions or disappears into a large concavity  56  that transitions between keel  80  and a tunnel  54 . A grate can be placed over the transition region  56  and a pump to hull interface having a large aperture can be mounted perpendicular to the hull at the fore region of tunnel  54 . A jet pump can be mounted within tunnel  54  and the tunnel protected with a ride plate. Hull  24  may also be seen to have a transition region  76  laterally extending on either side of keel  80  just forward of tunnel  54  and in the rear portion of transition region  56 . 
   Hull  24  also includes a first pair of longitudinal strakes  62  and a more outer, second pair of longitudinal strakes  64 . Center keel  80  and surrounding troughs  81  are located in a local, longitudinal strip  60  of hull  24 . Longitudinal, local strip  60  can be used to effectively describe the local geometry of the center keel and troughs. 
     FIG. 3  illustrates hull  24  from the bottom, illustrating front-most extent  50 , centerline  58 , rear-most extent  52 , tunnel  54 , and transition region  56 , as previously described with respect to  FIG. 2 .  FIG. 3  also illustrates hull lateral transition region  76 , center keel  80 , center keel troughs  81 , first strakes  62 , second strakes  64 , and center keel longitudinal strip  60 , also previously described with respect to  FIG. 2 . Tunnel  54  can include a pump to hull interface having a large water intake orifice at  74  that can be located in the tunnel to provide water to the jet pump from transition region  56 . 
     FIG. 4  illustrates a partial longitudinal strip  100  of a personal watercraft hull  101  lying between a pair of parallel, longitudinal lines  112 . Longitudinal strip  100  extends along a centerline or vertical center-plane  102  between a front extent  104  and rear extent  106 . In the example of the invention depicted in  FIG. 4 , the total watercraft length is about 126 inches long. The watercraft extends about 20 inches rearward of rear extent  106  and about 25 inches forward of the front extent  104 .  FIG. 4  thus illustrates the portion of the watercraft hull between about 16 percent of the way from the rear-most extent and about 20 percent of the way from the front-most extent of the watercraft.  FIG. 4  illustrates a vertical projection of a hull onto a plane, rather than the curved hull after being laid or rolled down onto a plane. Longitudinal strip  100  includes a center keel  115  having center keel troughs  114  on either side. Centerline  102  extends through a transition region  108  leading to a tunnel located to the rear of rear extent  106 . In the embodiment illustrated in  FIG. 4 , the distance from front extent  104  to rear extent  106  is about 80 inches. Longitudinal strip  100  is about 10 inches in width in  FIG. 4 .  FIG. 4  includes several forwardly looking view lines  5  through  10 . View lines  5  through  10  are about 10 inches apart and describe the location of the drawings in  FIGS. 5 through 10 . 
     FIGS. 5 through 10  describe a forward-looking, transverse cross-sectional view taken through bottom hull longitudinal strip  100  of  FIG. 4 .  FIGS. 5 through 10  proceed from front to rear along the watercraft hull. The geometry of the local region of the center keel may be best described by initially discussing  FIG. 8 . 
     FIG. 8  illustrates a transverse, cross-sectional view through bottom hull longitudinal strip  100  of  FIG. 4 , taken through view line  8 — 8 , looking forward. Bottom hull  101  includes center keel  115  and center keel troughs  114  disposed on either side.  FIG. 8  has been selected to illustrate the vertical slope and the region of greatest vertical slope of the center keel in a cross-section. At a center point  120 , on the outside surface of hull  101 , along centerline  102 , a line  122  has been drawn tangent to point  120 . Line  122  may be seen to be horizontal, having no vertical slope component. Extending transversely outward along the cross-section, a second point  124  may be seen, disposed on the hull outer surface in the trough region. A tangent line  126  may be seen drawn through tangent point  124 . Tangent line  126  has the maximum vertical slope taken along the keel surface within the longitudinal strip of this cross section. A second tangent line  126  may also be seen on the opposite side of centerline  102 . A “keel angle” θ may be defined between the two centerlines  126 . A “keel side angle” φ may be defined between vertical and tangent line  126 , also illustrated in  FIG. 8 . Traveling still further outward from centerline  102 , another point  128  has been selected on the hull surface. A tangent line  130  has been drawn through surface point  128 . It may be seen that the vertical slope of tangent line  130  has decreased relative to that of tangent line  126 . Proceeding still further outward from centerline  102 , yet another point  132  has been selected on the outer surface of hull  101 , where the hull shape begins to be essentially flat for a region. A tangent line  134  has been drawn through surface point  132 , illustrating the still decreasing vertical slope of the hull surface, relative to that of point  124 . 
   As used herein, “the point of greatest vertical slope in a cross-section” refers to the first maximum vertical slope region encountered when proceeding outward from the centerline. This slope extends downwardly and inwardly toward the center keel. Inspection of  FIG. 8  shows that a bulge or strake near point  132  could have a large vertical slope oriented downward and outward. This is not the maximum vertical slope described with respect to the center keel maximum vertical slope as the vertical slope is both not the first maximum encountered when traveling outward from a centerline and is also disposed outwardly and downwardly rather than inwardly and downwardly. 
     FIG. 9  may be used to illustrate another aspect of the present invention.  FIG. 9  illustrates the geometric nature of troughs  114 . A horizontal line  140  may be seen contacting center keel  115  at centerline  102 . Line  140  is a tangent line illustrating how a long, rigid member first end may be placed against center keel  115  at the outside surface at the centerline. The rigid member in some embodiments can be sufficiently long, for example, having a second end extending past the side of the watercraft so as to not fall into a local minimum. In other views of the invention, the rigid member may have a length just long enough to fall short of the most inward longitudinal strake. The rigid member may then be pivoted as indicated at  141  to assume the position indicated by line  142 . The rigid member has thus been pivotally rotated upward until it first contacts hull  101 . Note that in some hull geometries, after being pivotally rotated upward, line  141  may no longer contact center keel  115  at centerline  102 . Rather, line  142  should still cross centerline  102  but may no longer contact the outer surface of hull  101  at centerline  102 . Line  142  thus forms a “trough boundary” indicated at  144 . Trough boundary  144  is the boundary established by the rigid member previously discussed. The boundary lies in a vertical plane that extends transversely away from and perpendicular to centerline  102 . 
   Trough boundary  144  may be seen to extend between a first end  146  where boundary  144  crosses centerline  102 , or a downward projection of centerline  102 , and the opposite end of boundary  144  where the boundary encounters the outer hull surface for the first time at point  148 . The trough may be seen to have a maximum depth indicated at  154  at a point of maximum depth, indicated at  150 . The trough depth  154  has been taken as a normal, maximum distance between trough boundary  144  and hull  101  in trough  114 . Trough boundary  144  may also be seen to have a midpoint  152  that can also be used to establish a measurement point for the trough depth. The trough depth may be taken as a normal or perpendicular distance between midpoint  152  and hull  101  at trough  114 . The trough depth may also be measured as indicated by depth  156 , taken as a vertical distance from trough boundary midpoint  152  until hull  101  outer surface is encountered. 
   The change in hull geometry, and more particularly, center keel geometry may be discussed by referring back to  FIG. 5 .  FIG. 5  illustrates bottom hull  101  between lines  112 , centered on centerline  102 . Bottom hull  101  includes center keel  115 .  FIGS. 5 through 10 , unless otherwise indicated, are to scale. Specifically, lines  112  may be considered to be 10 inches apart, with the vertical and horizontal dimensions of  FIGS. 5 through 10  being the same as between the horizontal and vertical dimensions and as between  FIGS. 5 through 10 . Additionally,  FIGS. 5 through 10  may be measured and compared as between each other to better understand one embodiment of the present invention. 
     FIG. 5  is a forward-looking, transverse, cross-sectional view taken between lines  112  that are about 10 inches apart. The section taken through the center keel longitudinal strip is located about 27 percent of the way between the front-most and rear-most extents of the hull, about 34 inches from the front-most extent in the embodiment illustrated. Center keel  115  may be seen to have an essentially constant vertical slope extending outward from centerline  102  to line  112  limiting the outward extend of the longitudinal strip illustrated in  FIG. 5 . Center keel  115  of  FIG. 5  also has essentially no trough depth, as there is essentially no trough at this location. 
     FIG. 6  illustrates another forward-looking, transverse, cross-sectional view through hull longitudinal strip  100  of  FIG. 4 , taken about 35 percent of the distance from the front-most portion of the watercraft to the rear-most portion of the watercraft. This is about 44 inches from the front-most extent of the watercraft in the embodiment illustrated. Very small troughs  114  may be seen to be formed on either side of centerline  102 . In this region, center keel  115  begins to have a maximum downward vertical slope that is slightly larger than that over longitudinal section  100  as a whole. 
     FIG. 7  illustrates another forward-looking, transverse, cross-sectional view taken through view lines  7 — 7  of  FIG. 4 .  FIG. 7  is taken about 43 percent of the distance from the front-most extent of the watercraft to the rear-most extent of the watercraft, about 54 inches in the embodiment illustrated. Center keel  115  may be seen to have a more vertically downward inflection. Center keel  115  includes troughs  114  on either side, formed by center keel  115  having a vertically downward slope that increases as hull  101  is traveled from centerline  102  to lines  112 . 
     FIG. 8  illustrates a forward-looking, transverse, cross-sectional view taken through view line  8 — 8  of  FIG. 4 .  FIG. 8  is taken about 51 percent of the distance from the front-most extent to the rear-most extent of the watercraft, about 64 inches in this embodiment.  FIG. 8  was previously discussed to describe the geometry of the center keel. The maximum vertically downward slope of  FIG. 8  has increased relative to that of  FIG. 7 . The trough depth of  FIG. 8  has also increased relative to that of  FIG. 7 . The “keel angle” or “downward keel angle” has thus decreased from  FIG. 7  to  FIG. 8 , as the bottom hull is traveled from front to rear. 
     FIG. 9  illustrates a forward-looking, transverse, cross-sectional view taken through view line  9 — 9  of  FIG. 4 .  FIG. 9  is taken about 59 percent of the distance from the front-most extent to the rear-most extent of the personal watercraft, about 74 inches in the embodiment illustrated.  FIG. 9  was previously discussed to describe the trough depth and trough boundaries of the present invention. The keel angle and the maximum vertical downward slope of the center keel have increased from  FIG. 8  to  FIG. 9 . Likewise, the trough depth has also increased, proceeding forward from  FIG. 8  to  FIG. 9 . 
     FIG. 10  illustrates yet another forward-looking, transverse, cross-sectional view taken through view line  10 — 10  of  FIG. 4 .  FIG. 10  is located about 67 percent of the distance from the front-most extent to the rear-most extent of the watercraft, about 84 inches, in the present embodiment.  FIG. 10  is taken in a hull transition region. Center keel  115  may be seen as may center keel troughs  114  on either side. A tangent line  160  may be seen extending inward from the more outward location of the hull. Tangent lines  160  may be seen to intersect at point  162 , well below the outer surface of center keel  115 . A trough boundary line  164  may be seen, extending between centerline  102  and the first contact point indicated at  166 . The trough depth and the maximum vertical downward slope of the center keel in  FIG. 10  may be seen to have both decreased relative to that of  FIG. 9 . 
   Comparing  FIGS. 5 through 10 , the transition from a center keel having essentially no troughs on either side and a constant vertically downward slope across its cross-section, to a more vertically downward center keel having deeper troughs on either side may be seen. 
     FIG. 11  illustrates another personal watercraft bottom hull  200  having forward-looking view lines  12  through  22 , corresponding to  FIGS. 12A and 12B  through  FIGS. 22A and 22B , respectively. 
     FIG. 12A  is a forward-looking, transverse, cross-sectional view taken through bottom hull  200 , through view line  12  of  FIG. 11 .  FIG. 12A  is taken about 8 percent of the distance from the front-most extent of the personal watercraft to the rear-most extent of the personal watercraft, about 10 inches in the embodiment illustrated.  FIG. 12B  is a detailed view of  FIG. 12A .  FIGS. 12A and 12B  through  FIGS. 22A and 22B  may be understood to have the same vertical and horizontal scale within each drawing. The scale of the different.  FIGS. 12A through 22A  is the same as between these drawings. The similar scales as between the drawings better illustrates the embodiment of the invention illustrated, but the invention is of course not limited to this one embodiment.  FIG. 12A  includes a centerline or vertical center plane  202  extending through bottom hull  200 . A center region may be seen. 
     FIGS. 13A and 13B  illustrate a forward-looking, transverse, cross-sectional view taken through view line  13  of  FIG. 11 .  FIG. 13  is located about 16 percent of the distance from the front-most to the rear-most extent of the bottom hull. In the embodiment illustrated, this distance is about 20 inches from the forward most extent of the personal watercraft. A center keel  215  may be seen to be essentially having no trough on either side and no change in the maximal vertical downward slope traveling away from center keel  215 . 
     FIGS. 14A and 14B  illustrate a forward-looking, transverse, cross-sectional view taken through view line  14  of  FIG. 11 .  FIG. 14  is taken through a section located about 24 percent of the distance from the front-most extent to the rear-most extent of the personal watercraft, about 30 inches in the present embodiment. As may be seen in  FIGS. 14A and 14B  the bottom-hull has essentially no keel troughs on either side of the centerline. 
     FIGS. 15A and 15B  are taken about 32 percent of the distance from the front-most extent to the rear-most extent of the personal watercraft, about 40 inches in this embodiment. No troughs are yet visible. 
     FIGS. 16A and 16B  are taken through view line  16  of  FIG. 11 .  FIGS. 16A and 16B  are taken about 40 percent of the distance from the front-most extent to the rear-most extent of the watercraft, about 50 inches in this embodiment. Slight troughs  214  may be seen disposed on either side of center keel  215 . 
     FIGS. 17A and 17B  are taken about 48 percent of the distance from the front-most extent to the rear-most extent of the personal watercraft hull of  FIG. 11 . This is about 60 inches from the front-most extent in the embodiment illustrated. Troughs  214  may be seen to have a greater depth relative to those in  FIGS. 16A and 16B . The maximum downward vertical slope of the center keel in  FIGS. 17A and 17B  likewise is greater than that illustrated in  FIGS. 16A and 16B . 
     FIGS. 18A and 18B  are taken through view line  18  of  FIG. 11 , about 56 percent of the distance from the front-most extent to the rear-most extent of bottom hull  200 , about 70 inches from front-most extent in this embodiment. The downward keel angle may be seen to be more pronounced relative to that of  FIGS. 17A and 17B . The trough depth may also be seen to be deeper relative to that of  FIGS. 17A and 17B . 
     FIGS. 19A and 19B  are taken about 64 percent of the distance from the front-most extent to the rear-most extent of the personal watercraft bottom hull, about 80 inches from the front-most extent in the embodiment illustrated. The downward keel angle has decreased slightly relative to that of  FIGS. 18A and 18B , as has the trough depths on either side of the center keel. 
     FIGS. 20A and 20B  are taken through view line  20  of  FIG. 11 , about 71 percent of the distance from the front-most to the rear-most extent of the watercraft, about 90 inches in the embodiment illustrated. The watercraft bottom hull has begun rising up in a transition region  220  to meet the tunnel. The more forwardly located projection of the center keel may be seen at  222 . 
     FIGS. 21A and 21B  are taken through view line  21  of  FIG. 11 , about 79 percent of the distance from the front-most extent to the rear-most extent, about 100 inches in the present embodiment. Bottom hull  200  now rises almost directly upward to form tunnel  224 . The forwardly located center keel may be seen as indicated at  226 .  226  is a forward projection of the center keel, which, of course, is not downwardly protruding within tunnel  224 . 
     FIGS. 22A and 22B  are taken through view line  22  of  FIG. 11 .  FIGS. 22A and 22B  are taken about 87 percent of the distance from the front-most extent to the rear-most extent of the personal watercraft, about 110 inches in the embodiment illustrated. The embodiment illustrated in  FIG. 11  is about 10½ feet long or 126 inches in length. Bottom hull  200  continues to rise upward to form bottom tunnel  224 . The center keel may be seen in the background, as indicated at  228 , well forward of the cross-section illustrated in  FIGS. 22A and 22B . 
   The natural attitude of a watercraft at full speed is for the bow to be slightly up. On most current keel designs, the front is steep and sharp, and the rear is soft and shallow. During rough water operation, the rear section of the keel, having a soft shallow angle, is supported by the top version of the waves, the “peak” of the waves. Having a steeper, sharp section on the front portion of the keel will “cut” down to the lower portions of the waves, the “valley” of the waves. This can cause the hull to ride flat in the rough water. The present invention helps the bow ride slightly higher than the stern for proper attitude control and smoother ride in rough water conditions. 
   The present invention provides a personal watercraft that cuts through rough water in an improved fashion. In a rough water situation, where the boat is coming in and out of the water, applicants believe that the present design takes better advantage of the time when the hull is in the water. Applicants also believe that more of the water that the watercraft hull hits is channeled to the inlet and to the pump. This is as opposed to diverting it outside of the inlet. A shallow keel shaped just ahead of the tunnel or tunnel transition region may force water outward toward the sides to a great extent. The present invention, using the steeper keel angle and the larger concave troughs having greater depth on either side, can actually channel water better to the transition region and a tunnel and jet pump.