Analysis of materials, structures, components and fastenings
The subsurface condition of fibreglass, composite cored and timber structures is checked for delamination and decay. The most common analysis techniques are visual, percussion sounding and relative moisture testing.
Moulded fibreglass grid liners distributing the keel, mast, shroud and engine loads to the hull are common in modern yacht design and construction. Sounding, moisture and stress analysis targets these structures for delamination or disbonding as the result of a grounding.
Laminate blister analysis is based on our shipwright repair experience. There are many authoritative essays explaining the condition, chemistry, causes and repair methods for laminate blisters.
Structural fastenings including keelbolts, chainplates, rig components and more are all potential problem areas. For instance, stainless steel and aluminium in wet substrates, starved of oxygen are prone to crevice corrosion and work hardening. Analysis techniques include visual inspection, dye penetrant and radiographic X-ray analysis.
Traditional timber construction relies on thousands of metal fastenings and components for structural integrity. These, include copper, bronze, stainless steel, hi-tensile steel and wrought iron floors for cast iron ballast keels.
Electrochemical decay in way of copper fastenings, bronze shaft and rudder gland castings is a common issue in timber vessels. Removal of sample fastenings is a standard recommendation for analysis of corrosion and wastage.
Steel and aluminium hulls can present with galvanic corrosion between dissimilar metals, and electrolytic corrosion from stray current. A silver/silver-chloride (Ag/Ag-CL) reference electrode is used to perform a corrosion potential test.
Visual inspection is made of stainless steel shafts for oxidation. and pitting and cavitation damage to propellers.
Seacocks and components, shaft struts, propellers and cast rudders for dezincification. A process which selectively removes zinc from an alloy, leaving behind a porous copper-rich structure that has little mechanical strength.