fig1 through 3 show a first embodiment of an adjustable clamp 20 in accordance with the invention for clamping around the gunwales 10 of fiberglass boats 12 , 14 such that the clamping and releasing ( ie ., the un - clamping ) of the inventive clamp 20 does not scratch or mar the exterior finish of the fiberglass . fiberglass 12 , 14 boats are made in versions with planing hulls 12 . the commonest freshwater examples are bass boats and runabouts . such fiberglass boats 12 , 14 comprise a two - piece construction , namely : — a fiberglass hull 12 joined to a fiberglass deck 14 ( sometimes referred to as top deck ) at a seam . the hull 12 comprises a tub - shape having a sidewall ( usually an outwardly flaring sidewall ) that terminates in a rim edge . the top deck 14 usually forms a continuation of the sidewall for a short elevation above the rim edge of the hull before turning in then down at a shoulder typically called a ‘ gunwale ’ 10 . in bass boats , the term ‘ gunwale ’ is sometimes replaced with an alternate term , toe rail . that is , the counterpart gunwale structure in a bass boat is low compared to the floor , and hence the gunwale is sometimes referred to as toe rail . the seam between the hull 12 and deck 14 is typically covered by a rub rail 16 . typically , the rub rail 16 accepts fasteners through it and into both the hull 12 and deck 14 . the fasteners through the rub rail 16 into the hull 12 and deck 14 provides some of the mechanical joining of the hull 12 and deck 14 across the seam . the rub rail 16 is usually also the mount for a rubbery strip that serves as a fender . the rubber strip can also be arranged to cover the heads of the fasteners as well . again , the gunwale 10 comprises a raised rail 16 that extends peripherally around the outer edge of the deck 14 . typically the gunwale 10 in these kinds of fiberglass boats is hollow , comprising an inverted channel shape . sometimes the inverted - channel has an inverted square - u shape , other times and inverted rounded - u shape . nevertheless , such gunwales 10 can be reckoned as comprising an inboard flange portion and outboard flange portion joined by a crown web portion . the gunwale 10 gives both structural stiffness to the deck 14 as well as serves as a sort of a curb or wall to prevent items or passengers from easily falling out of the boat . the outboard flange portion terminates in a lower edge , and it is this lower edge which meets the hull 12 . the hulls of bass boats and runabouts are characterized by flare in the sidewalls of the hull 12 ( not shown ). generally , the sidewalls of the hull 12 are those portions that are above the hard chine ( not shown ), in contrast to the bottom of the hull ( also not shown ), which is below . that is , as the hull 12 terminates in its upper edge , just where it meets the lower edge of the gunwale 10 &# 39 ; s outboard edge , the flare is the outward - spreading of the sidewall of the hull 10 in the upward direction , when looked at in cross - section . this flare provides several things . when crashing waves , the flare throws spray away from the passenger compartment . the flare also provides for an expanded deck 14 for the same amount of hull 12 below the chine . flare is in contrast to flam . flam is where the cross - section of the hull is perhaps semi - circular , maybe even parabolic or the like ( not shown ). in any event , flam is more characteristic of displacement hulls , especially sail boats . the fiberglass in fiberglass boats 12 , 14 is typically given a smooth exterior finish that can be elaborately ornamented with lively colors and / or metal flake and so on . this smooth exterior finish typically comprises a gel coat layer . it is an object of the invention to clamp around a gunwale 10 of a fiberglass boat 12 , 14 without scratching or otherwise marring the exterior finish of the fiberglass . again , fig1 through 3 show a first embodiment of an adjustable clamp 20 in accordance with the invention for securing across the gunwales 10 of fiberglass boats 12 , 14 ( and in contrast to pontoon - boat rails , eg ., pontoon boats don &# 39 ; t formally have gunwales , but they have counterparts , which are typically square or rectangular aluminum tubes ). the adjustable clamp 20 comprises an outer jaw 24 in opposition to an inner jaw 26 , and an optional auxiliary jaw 25 for connecting to either the inner or outer jaw 26 or 24 as desired . in fig1 , a first optional position for the auxiliary jaw 25 is shown in solid lines and is shown attached to the inner 26 . a second optional position for the auxiliary jaw 25 is shown in dashed lines and is shown connected to the outer jaw 24 . the inner jaw 26 is tightened relative to the outer jaw 24 by a screw assembly 50 in the style of a hand vise . the inner and outer jaws 26 and 24 are furthermore articulated ( eg ., jointed within themselves and not relative to any other jaw ) with linkages as more particularly described below . the outer jaw 24 comprises an inner link 32 and an outer link 38 . the connection between the outer link 38 and inner link 32 is optionally perpendicular . preferably , the connection between the inner and outer links 32 and 38 is adjustable such that the effective lengths of either of the inner link 32 or outer link 38 lies between elongated and foreshortened extremes . optionally the links 32 and 38 can be constructed of spaced pairs of apertured bar stock to allow relatively easy re - configuring and adjustment relative to each other by pins or fasteners and the like . the outer link 38 preferably terminates in longitudinally elongated padded or grippy ends 42 utilized to contact the hull 12 . the wide grip pads 42 give the clamp 20 stability in the fore to aft direction . the grip pads 42 protect against scratching or marring the finish or the gel coat of the fiberglass hull 12 , as well as scratching the rub rail 16 . fig1 shows that the outer jaw 24 &# 39 ; s padded ends 42 should preferably contact the hull 12 below the rub rail 16 or , more preferably still , just underneath the rub rail 16 . the inner jaw 26 comprises an inner link 46 and outer link 66 . optionally the inner and outer links 46 and 66 for the inner jaw 26 comprise spaced pairs of apertured bar stock . the inner links 32 and 46 of the outer and inner jaws 24 and 26 are respectively connected together by a threesome of pins ( bolts ) 48 which relatively fix the connection between the inner links 32 and 46 of the outer and inner jaws 24 and 26 respectively in a relatively fixed alignment . such alignment is preferably an approximately perpendicular alignment . the screw assembly 50 provides for the squeeze between the jaws 24 and 26 . the screw assembly 50 optionally comprises a threaded - rod 52 ( eg ., all thread ) with a cam nut 54 for quick manual and tool - free clamping and release of the inventive clamp 20 . the screw assembly 50 interconnects between the inner link 46 of the inner jaw 26 and outer link 38 of the outer jaw 24 . as fig1 shows better , the inner link 46 of the inner jaw 26 furthermore carries a stand - off 56 for standing the inner jaw 26 &# 39 ; s inner link 46 off the crown or web portion of gunwale 10 . the stand - off 56 , like the outer jaw 24 &# 39 ; s hull - contacting forked end 38 , has a hull - contacting t - end that is covered in rubber pads . the screw assembly 50 &# 39 ; s threaded rod 52 is axially - confined on the inner jaw 26 &# 39 ; s inner link 46 by a pin or bolt 62 . to turn to the inner jaw 26 &# 39 ; s outer link 66 , the outer link 66 is pinned to inner link 46 by a pivot pin ( eg ., a bolt ) 68 . the inner and outer links 46 and 66 of the inner jaw 26 are variously adjustable relative to each other by moving the pin 68 around in various different ones of the apertures of the apertured bar stock . the spaced bars of the inner link 46 flank a central collar ( not shown ), and the spaced bars of the outer link 66 flank the pair of bars of the inner link 46 ( however , this arrangement could be readily reversed ). the outer link 66 terminates in a t - end that is covered in gel - coat protecting pads . again , bass boats have such low gunwales relative to the deck floor that the gunwales are sometimes alternatively referred to as toe rails . given a bass boat deck ( not shown ), preferably the outer link 66 &# 39 ; s t - end nests in the crease between the gunwale &# 39 ; s inboard flange and the deck &# 39 ; s floor . the outer link 66 includes a socket 72 for a strut 76 . the socket 72 is formed in or attached close to the t - end of the inner jaw 26 &# 39 ; s outer link 66 . the strut 76 is pivotally connected to the inner link 46 by cross - wise dowel nut 74 . the dowel nut spans between the spaced bars of the inner link 46 . the dowel nut 74 comprises a short section of round bar with a threaded hole bored through perpendicular to the axis of the round bar . the attachment point on the inner link 46 for the dowel nut 74 is inboard of the attachment point on the inner link 46 for the outer link 66 . the strut 76 optionally comprises a lag bolt . the strut 76 is threaded through the threaded - aperture of the dowel nut 74 , between the spaced bars of the inner link 46 , with the dowel nut pivotally caged in a pair of opposite apertures . the strut 76 threads through the dowel nut 74 until the strut 76 &# 39 ; s end opposite the nut end is jammed in the socket 72 for the strut 76 . among other things , the dowel nut 74 allows the strut 76 to pivot freely relative to the inner link 46 . fig1 allows reckoning that , the clamp 20 in accordance with the invention clamps tight over the gunwale 10 by a user handling the lever 78 of the cam nut 54 on the screw assembly 50 . it can be noticed in this view that the strut 76 axially opposes the outer jaw 24 &# 39 ; s hull - contacting ends 42 more on the same line than the line of the inner jaw 26 &# 39 ; s outer link 66 . hence the strut 76 assists in the squeeze on the deck 14 and hull 12 coming from two opposite directions on a diagonal line . the clamp 20 in accordance with the invention optionally comprises an auxiliary jaw 25 for either the inner jaw 26 or outer jaw 24 . the auxiliary jaw 25 preferably connects optionally to the inner link 46 of the inner jaw 26 ( as shown in solid lines ) or else to the inner link 32 of the outer jaw 24 ( as shown in dashed lines in fig1 ), but necessarily exclusively in the positions as illustrated . the auxiliary jaw 25 preferably comprises a construction like the outer link 66 of the inner jaw 26 , including its own pivot pin and axially adjustable threaded strut . that way , the auxiliary jaw 25 can be tightened independently of inner or outer jaws 26 and / or 24 . fig1 shows a non - exclusively preferred relation between the inner jaw 26 and auxiliary jaw 25 , wherein the inner jaw 26 contacts the deck 14 on the inboard side of the gunwale 10 , while the auxiliary jaw 25 contacts the outboard side of the gunwale 10 ( and not the hull 12 , which is below the rub rail 16 ). again , the auxiliary jaw 25 can be connected to either of the inner links 46 and 32 of the inner or outer jaw 26 or 24 , respectively , to do this . the auxiliary jaw 25 preferably has a t - end covered in pads for contacting the gunwale as shown . the adjustable clamp 20 in accordance with the invention affords quick connection and disconnection to and from the gunwale 10 a fiberglass boat 12 , 14 and thereafter serves as a base on which to mount any number of various , interchangeable accessories . non - limiting examples thereof include without limitation ( none which are shown ): — a fish locator display ( as mounted on the top of the inner jaw 26 ); a fish locator transducer ( as hung from the bottom of the outer jaw 24 ); rod holder ( s ); rod storage ; drink holder ( s ); an arch system for boat covers ; a pole system for any of a bimini , canopy , sun shade , or rain shield ; a frame system for either a tent or duck blind ; oar locks ; bow and / or stern lights ; bait bucket ( s ); lantern ( s ); black light ( s ); bumper ( s ); and so on . fig4 and 5 show an alternate embodiment of a clamp 22 in accordance with the invention . the threaded - rod screw assembly 50 of fig1 - 3 has been replaced by a turnbuckle screw 82 . the invention having been disclosed in connection with the foregoing variations and examples , additional variations will now be apparent to persons skilled in the art . the invention is not intended to be limited to the variations specifically mentioned , and accordingly reference should be made to the appended claims rather than the foregoing discussion of preferred examples , to assess the scope of the invention in which exclusive rights are claimed .