Hole reparing

Repair and re-surfacing

For the repair, the first survey should be done. The yacht carefully examined and tested in the main strength members, the hull, deck, and cabin arrangement. Generally, the probing is performed with hammering and visual inspection then estimates the condition. The hull is composite construction, for instance, inner laminate total thickness is 2.5 mm the foam core is 12mm and the outside laminate total thickness is 3mm, the fiber is E-glass. The surrounding damage is small, for instance, 50mm. Therefore, its repair area is 1000mm x 400mm. The damaged area should be marked ellipse shape of the circle with pencil. The circle should be covered 1000mm x 400mm.

Before the cutting damage area, the scarfing area also should be considered that is 30:1. The ellipse-circle should be bigger than the first estimation since inner-skin is 2.5mm and outer skin is 3mm, therefore, the inner-skin, core, and outer-skin have different diameter, 1000mm x 400mm, 1150mm x 550mm and 1150mm x 550mm, respectively. The ellipse-circle could be cut out with diamond-cutter, nicely.

Before the laminating, foam core and fibers should be prepared with proper size, especially, each fiber is different size because of scarfing. To prepare the fibers, be aware of that Inner-skin and outer-skin size also different.

Fig 1 Preparing the fibers (ABS, 2006)

By the (ABS, 2006), the new core will need to be slightly thinner than the existing core to accommodate the additional repair laminate thickness, or the core can be make holes to squeeze out the glue. The outer-skin is 3mm thickness, it will scarf 90mm. back-plate is also prepared for the inner-skin laminating. 

Laminating starts from the inner-skin, core, and then outer-skin, sequentially. For the inner-skins laminating, back-plate will be attached temporally behind the inner-skin then layer up fibers until fit proper thickness. Butt joint method is used for the foam core, before the joint, glue should be applied on the inner-skin then joint with old foam core. The last step, outer-skins are applied on the core. For the less labor, the peel-ply can be applied on the laminated skin.  

The surface should be prepared for the painting. After peel-ply strip off from the surface, there are some shining parts which should be sanded and dusted the surface off. When sanding the surface, the glass should not be damaged.

The painting process is the same as the case study 6.