TopTier, seakeeping and container cargo securing safety

Thomas Fuller (1608 – 1661 AD) wrote “It is skill, not strength, that governs a ship”. Good ships are designed to be safely operated instead of being intrinsically safe. That still holds firmly today. The TopTier JIP project addresses cargo securing safety on large container ships. Securing arrangements are based on design motion levels that do not include the truly worst case conditions that could occur. It is relied on good seamanship and conscious vessel handling to operate inside a safe envelope and avoid “off design” conditions. Incidents where vessel motions exceeded design values suggest that high motion levels may be reached before crews are alerted. Is there a gap between what is considered as extreme conditions in design world, and how good seamanship, can realistically operate the vessel inside that envelope.