Vespoli Rib Repair

        The rib and hull section anchoring the forward port rigger of the Vespoli double
was severely damaged in a dockside accident. Photographs showing the damaged area
from the interior and exterior of the boat are shown in Figures 1 and 2.

           
                                                Figure 1
           Exterior view of damaged section. Cracks marked by arrows
              extend through the outer laminate and into the foam core

          
                                                  Figure 2
              Interior view of damaged section. Cracks shown by arrows.
             The crack in the rib extends through the entire cross section

    Because of the monocoque construction of the boat, the transverse fractures
shown in the photos completely compromised the strength of the rib and its
ability to carry the rigger loads. Nonetheless, the bonding of the rest of the
rib to the hull and deck remained intact. It was thus desirable to effect a
satisfactory repair with minimal disruption of the undamaged areas.

    The repair was carried out in two steps: First a stiffening plate was
clamped to the outside of the rigger and splashbox to insure that the original
rigger angles were maintained. A drilling jig was fabricated and clamped to
the top of the rigger and two1/4" holes 10" long were drilled down the rib
axis spanning the rigger mounting holes. One hole extended into the cross-sectional
bulkhead below the deck (a stroke of luck!) and the other exited the bottom
of the rib beneath the decking. Two unidirectional carbon fiber rods
(18 x 10⁶ modulus; GraphiteStore.com)were then epoxied into the holes
and cut off flush with the top of the rib. The drilling setup is shown in Figure 3
and the drilled rib in Figure 4.

               
                                             Figure 3
                Drilling jig and external stiffening plate clamped
                  to the boat prior to drilling holes for graphite
                                    reinforcing rods.

        
                                                 Figure 4
              Axial holes prior to insertion of graphite reinforcing rods.

    Once the structure of the rib was stabilized by the rods, the interior and
exterior laminations in the damaged areas were ground down with an abrasive
wheel. The damaged cells in the foam core were cut away and rebuilt with a
thickened mixture of epoxy and microballoons. Multiple layers of glass cloth
were then bonded to the rebuilt core and scarfed onto the undamaged portions
of the skin laminations adjacent to the fracture. The rib loads in the repaired
rib are now shared by the internal rods and new skin laminations.
The rebuilt section of the rib seen from the interior of the boat prior to
painting is shown in Figure 5.

      
                                              Figure 5
                  Rebuilt and reglassed rib and interior cracks

    The surface laminations on the exterior were repaired in a similar fashion.
The completed interior and exterior repairs are shown in Figures 6 and 7. In
some areas the patches were not fully faired into the hull to preserve the maximum
thickness and strength of the repair in spite of the imperfect cosmetics. The
original boat was painted with custom colors no longer used by or obtainable
from Vespoli so there is some color mismatch in the repaired areas.

        
                                                        Figure 6
                                   Repaired section - interior view

       
                                                  Figure 7
                               Repaired section - exterior view