CHAPTER II, SECTION 1 Office. The displacement of water on the staff from crest to trough was observed visually and logged as each wave passed. Wave periods and heights were recorded to the nearest half-foot. As a result of the exploration borings and laboratory tests, the following general criteria were set up: (a) Structures which were not critical from a settlement standpoint were supported on conventional spread footings. Wind speeds were taken with a hand ane- mometer from the highest point on the bridge of an LST. Wind direction was ascertained to the nearest 16th point of the compass. (b) For structures where allowable settle- ment was extremely critical, 12-inch steel H-piles from 40 to 80 feet in Currents in the lagoon were measured in the passes by computingthe drift of wood blocks from an anchored vessel, and in the ocean b fixing the position of a free-floating wave staff over a period of several months. length were used. Figure 2-2 shows 12-inch H-piles, 80 feet long, driven and capped. This foundation was used for Station 20. Cloud cover was estimated visually by per- Detailed design criteria subsequently used centages in 10% increments. proved adequate; the final results showed there The results showed that the wind regime was no appreciable settlement of any of the structures beyondcritical limits. was very stable, with the prevailing direction as WAVE ACTION STUDIES. A survey was made of the Bikini Atoll early in April 1953 to determine wave conditions, wind conditions and the relationship between wind and waves. The study also included cloud cover and current ob- ENE with extreme observed directions of NE and ESE. The wind speed was between four and 20 knots with the greater percentage between nine and 19 knots. The mean cloud cover during daylight hours was 3/10. Low cumulus waspresent nearly always with an average base height Wave periods and heights were measured with a wave staff. This wave staff was of the type used by the U. S. Navy Hydrographic in all same knots at all of 2,000 feet. It was found that the currents servations. of the passes were approximately of the velocity, the speed ranging between 0.5 and 1.5 knots, without change in direction tides. a: a 7 ee an fee ri 3 be Figure 2-2. Page 2-4 a 3 ee é & : " an ai ’ A a7 Typical H-pile Foundation .'