1. Canada-Newfoundland and Labrador Offshore Petroleum Board ICRARD 2010 W. Bobby

2. Canada-Newfoundland and Labrador Offshore Petroleum Board Challenges Multi-directional waves -Directional wave effects on large offshore structures. St. Q. Isaacson, Michael (Univ of British Columbia, Vancouver,, BC, Can); Journal of Waterway, Port, Coastal and Ocean Engineering, v 112, n 4, p 482-497, Jul 1986 "Transverse components (sway and roll) of the force response... Are very significant in short crested seas, with greater magnitudes for a greater degree of directional spreading of waves." -Difference-frequency wave loads on a large body in multi-directional waves, Kim, M.-H. Applied Ocean Research, v 14, n 6, p 353, 1992 "It is seen that the slowly varying wave loads are in general very sensitive to the directional spreading function of the sea, and therefore wave directionality needs to be taken into account in relevant ocean engineering applications."

3. Canada-Newfoundland and Labrador Offshore Petroleum Board -Drift motions of a floating barge in regular and random multi-directional waves, Nwogu, O. and Isaacson, M. Source: Proceedings of the International Offshore Mechanics and Arctic Engineering Symposium, v 2, n 8 th, p 441-448, 1989 "The tests showed an increase of the roll, sway, and yaw motions of the barge in multi-directional waves" -Second-order mean wave forces and moments on ISSC TLP in uni- and multi-directional random seas, Liu, Y.H., Kim, M.H., Kim, C.H. and Boo, S.Y. Proc Second Int Offshore Polar Eng Conf, p 218-207, 1992 "The resultant horizontal drift force in multi-directional seas may be greater than that in uni-directional seas. Hence, the effects of directionally spread seas must be taken into consideration for the accurate prediction of mean wave forces in realistic short-crested irregular seas." -Drift motions of a floating barge in regular and random multi-directional waves, Nwogu, O. and Isaacson, M. Proceedings of the International Offshore Mechanics and Arctic Engineering Symposium, v 2, n 8 th, p 441-448, 1989

4. Canada-Newfoundland and Labrador Offshore Petroleum Board "The tests showed an increase of the roll, sway and yaw motions of the barge in multi-directional waves." -Slender-body approximation for slowly-varying wave loads in multi-directional waves, Kim, M.H. and Chen, W. Applied Ocean Research, v 16, n 3, p 141, 1994 "In-line moments... increase in very low frequency region with increasing directional spreading. In that low frequency region, it is also shown that the slowly-varying transverse moments can be as large as or even greater than the in-line moments even for narrow spreading functions." -Second order wave forces and moments in multi-directional seas, Jorgan R. Krokstad "The results show that interaction effects on the moments are especially large for the wave directions 0 nad 90 deg where no moment is induced by one of the two directional wave components isolated."

5. Canada-Newfoundland and Labrador Offshore Petroleum Board Codes are silent on the need to consider multi-directional waves The next draft of the ISO structures may reference multi-directional waves However, there is no specific guidance on the analysis for multi- directional waves Model testing is done for the site specific wave climate (including multi- directional waves) Design review organizations (class societies) do have capability for reviewing analysis for multi-directional waves To what extent do multi-directional waves affect monohulls, semi- submersibles, jack-ups, jacket structures and gravity based structures?

6. Canada-Newfoundland and Labrador Offshore Petroleum Board Application of IEC standards Annex B of IEC 61508-6 Part 6: Guidelines on the application of IEC 61508-2 and IEC 61508-3Example technique for evaluating probabilities of hardware failure indicates that the calculations are based on the assumption that component failure rates are constant over the life of the system The IEC standard indicates that in most situations, safety is achieved by a number of protective systems which rely on many technologies (for example mechanical, hydraulic, pneumatic, electrical, electronic, programmable electronic) and that while the International Standard is concerned with electrical/electronic/programmable electronic (E/E/PE) safety-related systems, it may also provide a framework within which safety-related systems based on other technologies may be considered. Many safety components such as safety valves that are usually dormant do not have a constant failure rate. Their failure rate is a function of the frequency of testing of those components The standard should provide guidance for application to components that do not have a constant failure rate

7. Canada-Newfoundland and Labrador Offshore Petroleum Board Iceberg-structure interaction Pressure area curve It is traditionally understood that the average iceberg-structure interaction pressure reduces with increase in iceberg-structure contact area Also that there are areas of high pressure within the iceberg- structure contact area There are two differing opinions from the researchers on iceberg- structure interaction A small group of researchers are of the opinion that as much of the information is based on low impact energies and large iceberg-structure contact area aspect ratio, there may be potential for higher pressures than traditionally considered and that the size of the high pressure zones could be larger with higher energy interactions

8. Canada-Newfoundland and Labrador Offshore Petroleum Board Iceberg design return period The ISO structures standard recommends a 100 year return period for iceberg loads Iceberg loads do not taper off as wave loads at 100 year return period What should be the design return period for iceberg load?