while the invention is susceptible of various modifications and alternative constructions , certain illustrated embodiments thereof have been shown in the drawings and will be described below in detail . it should be understood , however , that there is no intention to limit the invention to the specific form disclosed , but , on the contrary , the invention is to cover all modifications , alternative constructions , and equivalents falling within the spirit and scope of the invention as defined in the claims . the preferred embodiment of the roof rack of the invention is shown in fig1 . it includes a generally planar floor panel 16 , a sloping wind deflector 18 , a rear wall 44 , a left side wall 20 , and a right side wall 22 . the roof rack can be made from a number of materials , but the preferred material is a high impact plastic of which many different compositions can work . the device could also be made out of other materials such as metal , wood or a plastic with internal metal reinforcement . the roof rack 10 has a floor panel 16 that is generally flat and covers more or less the entire floor of the roof rack 10 . the floor panel 16 may have mounting holes 12 positioned thereon . the mounting holes can be large holes such as 12 , or smaller holes shown as 68 , which can provide a number of mounting positions for u - bolts 40 . drain holes are also present to allow rainwater to drain from the rack . the mounting holes 12 would typically be positioned so that a strap can be passed through a pair of mounting holes 12 and around a load bar 34 , as shown in fig4 . the holes 68 would be utilized with the u - bolts 40 as shown in fig5 . the wind deflector 18 , left side wall 20 , right side wall 22 , and rear wall 44 may also contain side wall holes 14 . these provide points to which cargo can be latched and through which load straps 24 can be passed . the side wall holes can take several configurations , several of which are shown . the slots 64 of fig2 are narrow slots in the side walls through which a strap can pass . the holes 66 of fig2 are holes in the side walls through which bungee cord ends can be secured or additional hooks , snaps , loops or other attachment devices can be attached . fig2 is a side view of the roof rack 10 of the invention , showing a cargo box 32 secured in place by a pair of load straps 24 . besides the load straps 24 , cargo boxes or other complimentary mounting pieces can be secured by other conventional means , such as by nuts and bolts , clamps or by straps . one preferred embodiment of the cargo box 32 includes tabs 60 , which fit into slots 70 in the floor of the roof rack . the tabs 60 can protrude to the underside of the roof rack , where they can be secured with a carabiner 62 , lock or pin . a long pin can be used to extend through more than one tab 60 for securing one or more cargo boxes 32 . the open and unstructured nature of the interior of the roof rack 10 allows large and odd sized articles to be carried on the roof of the vehicle . this can include boxes and bins , and other more or less rectangular objects , as well as oddly shaped objects such as bicycles or other objects that need to be carried . the roof rack 10 of the invention is attached to load bars 34 , as shown in fig2 . the load bars 34 are mounted on load bar towers 36 , which are attached to the vehicle in various ways . fig3 shows one of many possible types of mounting brackets that can be installed in the roof rack 10 . fig3 shows a bike fork mount 26 and a bike rear wheel mount 28 , on which is secured a bike 30 . other components include a board / boat bumper 58 , shown in fig1 . this is a piece that can be added to allow the rack to carry boards ( sail , surf ), canoes , kayaks or other bulky objects . the bumper 58 fits over the wind deflector and a similar unit fits over the rear wall of the rack to provide a board / boat lifting capacity to the rack . fig4 and 5 show two different devices for attaching the roof rack 10 to the load bars 34 of a vehicle . a load bar strap 38 may be used , which passes through a pair of mounting holes 12 . the load strap 12 could be secured by a conventional buckle 50 shown or by other securing devices . shown in fig5 is a load bar clamp 40 , which attaches the roof rack 10 to the load bar 34 . the clamp 40 may be secured by a conventional nut 52 or it may be secured by an attachment clamp 54 . shown in fig6 is the roof rack 10 of the invention in a cut - away side view . shown in fig6 is a ski 48 attached to a pair of ski mounts 42 . the ski mounts 42 can be attached to the roof rack 10 by a number of different types of devices , including clamps , nuts and bolts , peg and pin , or other types of mountings that makes the ski mounts 42 removable from the floor panel 16 of the invention . one preferred configuration of the ski mounts 42 is a design which is configured to carry skis or to serve as a bike rack , at the option of the user . this capability would allow the user to have one component for these two purposes , and do away with the seasonal rotation of these components . further , the ski mounts 42 are preferably configured for quick mounting to the floor of the roof rack , by a hand rotating nuts , by a button release and lock , or other quick change features . fig7 shows another option of the roof rack of the invention ; a rack cover 56 . this would fit over the side walls , as shown , and latch in place by conventional attachment means . the invention provides a more flexible system for carrying a variety of load types and shapes , including boxes , interlocking cargo boxes , duffel bags , bikes , skis , boards , boats , packs , suitcases , and other items . unlike prior art systems , the rack of the invention can carry bikes at the same time as carrying duffel bags and boxes , and can carry a boat , as well as a bike , without switching gear specific components . while there is shown and described the present preferred embodiment of the invention , it is to be distinctly understood that this invention is not limited thereto but may be variously embodied to practice within the scope of the following claims . from the foregoing description , it will be apparent that various changes may be made without departing from the spirit and scope of the invention as defined by the following claims .