Analysis of structures, materials, components and fastenings
Visual, percussion sounding and moisture testing are the techniques we use to analyse fibreglass, timber and composite structures for delamination or decay.
Analysis of laminate blisters is based on our shipwright experience. There are many authoritative texts explaining the condition, chemistry, causes and repair methods.
Fibreglass structural grid liners distributing the keel, mast, shroud and engine loads to hulls are now common. In addition to visual, sounding and moisture testing, we analyse these structures with dynamic stress testing.
Structural fastenings including keelbolts, shroud plates, rigging and components can present with issues. Stainless steel and aluminium in a wet substrate, starved of oxygen are prone to crevice corrosion and work hardening from stress. We rely on visual inspection, dye penetrant testing and occasionally radiographic X-ray analysis.
Traditional timber construction relies on metal fastenings and components for its structural integrity. Copper, bronze, stainless steel, monel, steel and wrought iron. We may recommend sample fastenings are drawn for inspection.
Electrochemical decay of timber in way of copper fastenings, bronze shaft and rudder gland castings in aged vessels. Soft furred timber and white alkaline salt deposit are the indicators, and decay is usually localised to the fitting.
Steel and aluminium hulls may present with galvanic corrosion between dissimilar metals or electrolytic corrosion from stray current. We use a silver/silver-chloride (Ag/Ag-CL) reference electrode to perform a corrosion potential test.
Visual inspection is made of stainless steel shafts for oxidation, pitting and cavitation damage to propellers.
Seacocks, plumbing fittings, shaft struts, propellers and rudders are examined for dezincification. A process which selectively removes zinc from an alloy, leaving a porous copper-rich structure with little mechanical strength.