Many fiberglass boats are constructed by attaching two main moldings, the hull 18 and the deck 16 as shown in FIG. 16. The deck molding is often attached to a lip around the top edge of the hull molding. A plate 15 on top of the edge of the deck is often used as the top of a three piece structure: plate, deck and lip of the hull. This structure is often connected with bolts 19 and nuts 20, or such fasteners, that are often four or six inches apart around the edge of the deck piece 16.
The plate 15, described above, is often part of an aluminum extrusion profile that is in the shape of a modified ‘L’ or ‘T’, that is lying on its side. The horizontal surface serves as the connecting plate 15, above. The vertical surface is called a toe rail 14 and serves to help prevent objects, including people, from sliding off the boat deck 16 and into the water. NOTE: the term ‘toe rail’ is used somewhat interchangeably in boating to sometimes define the vertical flange 14 and sometime to define the aluminum profile extrusion that comprises the vertical flange 14 at the edge of a boat deck 16.
Fenders are often the edge of an automobile and as such are often damage points. A toe rail is often the edge of a boat, and as such is often damaged when contact is made with things like pilings, when the boat is heeled (canted), like in a storm wind.
The damage is often in the form of segments of toe rails 14 that are bent inward towards the center of the boat as shown in FIG. 17. Toe rails 14 are continuous pieces so the amount of bending varies along the length of the damage from the deepest damage point out to where the rails are still straight. The damaged segments can be from a few inches to several feet long. Toe rail damage is rarely more than 45 degrees of inward bending. Aluminum toe rail extrusions often have a vertical flange 14 that is thicker at the lip than at the base. The bending damage is usually at that base, near the flange root, where the bending stresses are the greatest and where the wall thickness is the lowest.
Repair requires replacement of the aluminum extrusion profile or spreading the vertical flange 14 (the toe tail), FIG. 17, back away from the horizontal flange 15 (the hull/deck connection plate). The replacement option is exceedingly laborious as much permanently installed interior often has to be removed to get to the interior side of the connections, such as the bolt nuts 20. The interior includes items such as headliners (ceilings) and cabinetry. The replacement option is further complicated with older boats and ‘out of business’ boat builders and/or profile providers.
Pounding the vertical toe rail 14 back into a straight position is sometimes done and sometimes successfully. The strength of the aluminum profile extrusions makes it difficult to apply enough pounding impact to straighten the profiles, much less do so in a controlled manner. Control is important because the continuous profiles make it difficult to isolate repairs. Pushing one flange location also affects adjacent portions of the profile. The pounding action also puts impact tensile stress (prying force) on the hull-deck connection and may cause damage to this critical connection. The major problem with the pounding approach is that the repair can be readily seen. Damage to hull-deck connections and seals 17 can not be so readily seen until leaks enter the boat or major hull-deck separation occurs in a storm.
The pounding action also has potential for warping a toe rail 14, lip to root, while it is being straightened along its length down the boat. Using a piece of 2×4 to spread out the pounding still puts prying stress on the horizontal flange 15 and still has warpage potential. But as mentioned above, it sometimes works, insofar as what can be seen.
A prying action to straighten the toe rail flange 14 has the same problem as pounding the toe rail 14, in that the prying action also puts prying stress on the deck plate flange 15 and its hull-deck connection. The potential for damaging hull-deck connections and seals 17 is the same as described above.
Boat toe rail aluminum extrusions often have vertical flanges 14 that are near, or less than, two inches high. The thickness of the root of the vertical flanges 14 is generally ⅛ to ¼ inch thick. The flange fillets are usually in the range of 3/16 inch radii.
There are a range of different boat toe rail profile geometries. This influences where a hooking action is needed on the outside of the profile, the side on the outside of the hull.
Some of the profile geometries have relatively delicate surfaces where hooking action would occur. For example, a SAGA 43 sailboat uses a profile (dark area in FIG. 16) with an open rectangular slot for insertion of a rubber rub rail (bumper). There is a 3/32 inch thick aluminum part to that slot that could be damaged by excessive local compression from a C-clamp device at that point.
The fiberglass deck surfaces 16 under the toe rail extrusion profiles, the hull-deck connector flange 15, are easily gouged by metal bolt heads or bolt turning tools. Easily gouged, if trust bolt 5 lengths, geometries and/or thrust angles cause bolt head or tool interfere with such fiberglass.
Repair equipment can be designed with engineering principles, but such calculations are exceedingly laborious, if possible, for some applications. For example the many different profile shapes for boats' aluminum toe rail extrusions would require significant calculations for what stresses to direct and where for each repair application. The almost infinite variability of crushing damage further complicates the ability to use calculations alone to design precise repair equipment. Force and stress calculation difficulties are further exacerbated by the unknown effect of the portions of the continuous profiles that extend beyond the sides of a straightening device or action. The profiles are often designed with thickened lips to reinforce the profiles, which add yet more to the stress prediction complications.
The normal procedure of overdesign to accommodate uncertainties is complicated by the small geometry available inside tight angles between crushed flanges.
Archimedes, a Greek engineer, described screwing circa 1250 B.C.
A screwing action is described in a C-clamp device by Perrin's April 1864 U.S. Pat. No. 42,222. Perrin's device is used to press planking into place for wooden boat construction. It has a ‘C’ plate to permit the device to reach around the object being pressed. The pressing, or pressing together, action of Perrin's device is a common characteristic of C-clamps. The small pressure pad at the end of the thrust bolt is in common usage for C-clamps and distributes the load enough to avoid damaging the surface of the piece being acted upon. However the pressure pad does not distribute the force enough to control deformation of the piece being acted upon. The location of the piece's deformation(s) is instead controlled by the geometry of the piece and/or the geometry of whatever the piece is being forced against. For example, the piece being deflected in Perrin's illustration shows wooden ship planking that is warping under clamping stress, as would be expected, as it is bent around a frame, versus being bent as a straight piece.
Perrin's C-clamp has adjustable hooking action to accommodate variations in the geometry of the boats' ribs. The adjustable nature of the hooking action is somewhat unusual as most C-clamp hooking action is another simple contact pad that again distributes the load just enough to avoid damage to the surface being contacted as illustrated in Adt's January 1870 U.S. Pat. No. 98,656.
A more linear hooking action is described in Payne's October 1932 U.S. Pat. No. 1,882,297. However Payne's device has two problems for repairing bent toe rails. One: if it is used to grip the end of a flange, it would have the same deformation situation as described above for Perrin's U.S. Pat. No. 42,222. The piece being straightened would still be subject to warping from root to lip while the lip was being pulled away from the other flange.
Payne's device has an offset design that can impart a twisting/straightening force. Payne described a use of the device for straightening door frames. One could also visualize using this design for prying flanges apart if one of the flanges were secured to something else. However, Payne's device's second problem is that such prying action would also put prying stress on the secured flange. In the case of a boat's hull-deck connecting plate 15, such prying stress may damage that securing connection, as discussed earlier.
Hoffman's October 1922 U.S. Pat. No. 1,433,617 describes a hanger support (clamp) on a flange. It could be modified with pressure plates, versus the pressure points in Hoffman's patent description, and could be used to straighten a flange. The other parts of the profile would have to be secured to something substantial. Again, the approach would provide problems for boat toe rail repairs because of the collateral transfer of the prying stresses to the deck flange 15.
Pivoting beams or plates are commonly used to bend metal into flanges. Latta's March 1843 U.S. Pat. No. 3,022 described the use of pivoted bending pieces to force a flat plate into a U shape for steamboat water-wheel stirrups.
Smith's August 1954 U.S. Pat. No. 2,687,162 describes several useful concepts that aid the design of metal bending equipment. He utilizes a bolt driven pivoting block or pressure plate to force the piece being bent around a die that fits the corner of the piece being bent. The plate negates some of the flange warping problems, described above under the discussion about Perrin's U.S. Pat. No. 42,222. The pivoting action negates more of the warping concern. A pressure plate that only contacts the lip of the flange has the same warping problems described above under the discussion about Payne's U.S. Pat. No. 1,882,297. Whereas the pivoting plate in Smith's device description supports the entire piece to be bent, as it is bent around a pivot point. Smith describes C-shaped side walls or dual ‘C’ plates. The dual structure provides a convenient location for mounting a pivoting housing unit for a thrust bolt. He secures the ‘C’ plates with a combination of welded cross pieces and a pivoting piece.
Stott's October 1950 U.S. Pat. No. 2,525,625 for bending metal uses a rotating clamp that secures the metal between plates as the metal is bent to form a flange. Such a device also avoids lip to root warpage as the metal is bent to form a flange.
Latta's, Smith's and Stott's patents all describe how to create flanges from flat stock. In all three cases the base materials/stock is bent with compressive bending forces from outside the flanges being formed. Likewise the backing forces against the bending compression are outside the flanges being formed. However, prying flanges apart requires bracing in the opposite direction, and against prying forces versus against compressive, forces. While there are some overlapping mechanical concepts, prying flange faces apart versus pressing flange faces toward each other presents a different set of needs than the three inventions, above, were created to address. All three inventions have limitations to straighten bent flanges back apart, especially with on-board repairs of bent-in boat toe rails.
Prying flanges apart, like in a repair operation, requires the bending force be able to get inside between the flanges. The three flange forming inventions above, designed for flange manufacture, have the bending force applied from the opposite direction, outside the flanges. There is little interior space available at the intersection of two flanges that have been crushed together, versus the space available to produce flanges from flat stock. The descriptions in the three flange forming inventions, above, make it difficult to visualize how they would get pivoting thrust plates into tight flange intersections.
If one also has to get the opposing backing force into those intersections of bent together flanges, then the geometry problem of using the three flange manufacturing methods, above, become even more difficult to visualize as a method to repair bent-together flanges.
One could visualize avoiding the need for a backing force inside the flanges by using a secured flange as the opposing backing force for a bent flange repair. In the case of a boat toe rail the unmoving flange 15 can be the deck plate/flange 15 used to secure (and seal 17) the fiberglass deck 16 to the fiberglass hull 18. However the prying stresses will also apply to the securing system used to secure the unmoving flange 15 to the other structure. Serious prying stresses are to be avoided with these connections as such stresses may damage critical hull-deck connections/seals.
The prying action to repair bent flanges also has to face the problem described earlier of prevention of the opposing forces from pushing the device out of the flange intersection versus forcing the flanges back apart. The need for a hooking action opposite of the flange intersection was described earlier. The concept of multiple connection/pressure points is illustrated in Hewat's June 1953 U.S. Pat. No. 2,642,905. He grips an item with compression at two ends and then has a pivoting thrust bolt available for further metal clamping or moving. This invention does not lend itself to prying a boat's bent toe rail flange 14 back from the toe rail's deck plate 15. Deck plates 15 are often chamfered or rounded at their ends, FIGS. 16 and 8. The deck plate 15 is left with no place to attach a compression clamp at its outer end that squeezes into the plane of the plate 15. This also creates problems with using the preceding three flange manufacturing inventions, if their application was attempted for repair of crushed-in flanges.
McAleenan's July 1929 U.S. Pat. No. 1,721,964 describes a machine to adjust the shape of profiles. The invention describes putting a ‘T’ shaped profile beam into a dual biaxial press and retaining the ‘T’ shape while forming a longitudinal contour around a vertical axis. A flat die comes down and protects the top of the ‘T’ from deforming as a die is moved horizontally against a facing static die. The system depends on the ability to have dies and backing dies in two planes. This is a reasonable concept for manufacturing curved profiles of the same design from straight beams.
One could visualize how McAleenan's concept could be used to straighten bent flanges as the closing of the dies would force the flanges into straight positions. The first problem with using McAleenan's double die concept for bent boat toe rail repair is the definition of straight. Two straight dies coming together will not necessarily produce a straight flange 14 like in FIG. 16. A bent flange 14, like in FIG. 17, has to be overstraightened enough past its yield point to elastically recover to a straight position. The random bending amount of damaged toe rails and the variability of toe rail profiles conspire to make it exceedingly difficult to calculate the necessary angle offsets for die designs. The calculations are further complicated by how straight/curved the dies have to be from root to flange tip to ensure the final straight die is not warped in the process.
One could use shims to achieve the necessary overbending beyond the yield points. For a repair operation, a shim approach substitutes a repetitive, laborious cut and fit activity for ‘some’ of the angle calculations. The repetitive shim cutting, flange bending, recutting and rebending, etc. pushes costs and quality.
However, a second, bigger problem with McAleenan's dual axis, dual die system is the collection of geometry problems to apply such a system to an on-board boat toe rail that has to be straightened. A horizontally moving die to straighten a toe rail flange 14 would have to have some opposing force behind it and attached to the profile. Otherwise, the moving horizontal die would just be another lever action with its attendant problems, as described above in the discussion of Payne's U.S. Pat. No. 1,882,297. But as discussed above with Hewat's U.S. Pat. No. 2,642,905, there is rarely a reasonable place on boats' toe rails to apply such an opposing force behind the horizontally moving straightening die.
If the horizontally opposing force is moved to the opposite side of the profile, behind the profile and opposite to the deck flange 15, the horizontal die becomes a prying lever that also applies undesirable collateral prying force to the deck plate/flange 15.
But McAleenan's concept could be applied in part by compressing a bent toe rail between two beams, using just a horizontal axis of compression against a bent toe rail and no constraining vertical forces. The double die/beam procedure would apply some prying forces to deck plate 15 areas on the damaged toe rail 15 sections that would be matched by compression forces on the deck plate 15 areas of adjoining undamaged segments.
The bigger issue with the dual die single axis approach is that it has more potential for averaging the bend angle along a length of the toe rail extrusion that straightening per se. Specifically, for the dual die approach to be successful the compression beams have to be long enough that the resultant average bend angle would have the damaged sections near their original right angle. This would necessitate long, strong beams of the exact horizontal curvature of the boat and with the right amount of overstraightening built in at the right places. Such custom made die beams would require even more effort and expense that the laborious task of just replacing the toe rails.
One of the repair techniques in practice today for straightening bent toe rails is to accommodate hull curvature by using straight and shorter versions of the double die/beam concept above, sometimes with a shimming action included. The repair results require skill and often still end up ‘good nuff’ in the eyes of the repairman as the bend damage is ‘averaged’ out more than it was initially, maybe to the satisfaction of the boat owner, maybe not.
There are devices that are designed to pry items apart. Healy's April 2001 U.S. Pat. No. 6,209,427 B1 describes a device for prying open parts of an automobile suspension. The device depends on the ability to push items apart that are roughly parallel to each other. That is not the case with intersecting reasonably straight flanges that are bent towards each other like boats' bent toe rails. Application of prying force in Healy's device would tend to force the device out from between the flanges versus forcing them apart.
Clamps on the ends of Healy's prying surface might work with intersecting flanges if they were strong enough. However, the end of a boat toe rail profile deck plate 15 has no way to attach such a clamp, while the profile is attached to the boat 16.
Incorporate all references in their entirety.