Many vessels in the marine environment are subject to agerelated deterioration. In the main, this is caused by corrosion wastage, fatigue cracking and localized abrasion damage. The maintenance, repair or renewal of heavily damaged structures is complicated and costly.
Mechanical damage is an operational hazard, and tugs, workboats and barges are subject to a higher level of such damage when compared with other vessels due to their mode of operation. Damage to ship structures occurs during fendering, lightering, loading/unloading, and also from impact damage when items are dropped by crane, ropes and hawsers, ice abrasion and so on. Not only does localized damage to the external coating system occur, but also cracking and detachment of the protective coating from the back face of the damaged plate can initiate internal corrosion. In practice, the best that can be achieved is that the levels and effects of agerelated deterioration must be anticipated in design, and must be monitored closely and effectively controlled during construction and service.