Good: Good corner helideck location with significant overhang and air gap. Structures close to the helideck are mainly open and porous to the wind. Flare booms for well-test operations are both reasonably distant from the helideck and should be visible when in use.
Good: The example jack-up drilling platform shown here has a helideck with large overhang and generous air gap, and it is located higher than most of the solid superstructure. Structures above the level of the helideck are generally porous. (Most jack-up drilling platforms have good helideck locations.)
10.8.3 Tension Leg Platforms
Good: This tension leg platform (TLP) has a high corner location helideck with an air gap. Also the generally open and porous design of the superstructure will reduce wind flow problems. Wave induced motions are generally small for a TLP. They are almost zero in roll, pitch and heave, whilst the larger surge, sway and yaw motions are normally at very low frequency.
Bad: The downward pointing gas turbine exhausts directly under the helideck are likely to result in a cloud of hot gas enveloping the helideck in light wind conditions.
Good: Wave induced motions for this tension leg platform motions will generally be small. They are almost zero in roll, pitch and heave, whilst the larger surge, sway and yaw motions are normally at very low frequency.
Bad: The helideck is mounted relatively low on the superstructure and is close to a large solid construction, which will cause significant downdraft and turbulence when up wind. Upward facing gas turbine exhaust stacks are insufficiently high to ensure that the hot gas plume will pass above the helicopter flight path.
10.8.4 FPSOs
Good: The high location of the helideck and generous air gap mean that it is very unlikely to suffer from any aerodynamic turbulence, particularly as the vessel usually operates heading into wind.
Bad: The extreme forward location of the helideck means that vessel pitch will be experienced at the helideck as heave motion and acceleration. The high location of the helideck means that vessel roll will be experienced at the helideck as sway motion and acceleration. Pilots also dislike bow-mounted helidecks because of the lack of visual cues when vessel is heading into wind.
Good: Helideck at the stern will experience lesser wave induced motions than if it were at the bow. It is also reasonably high compared with the bulk of the superstructure, and is unlikely to experience severe turbulence even though the helideck will usually be downwind. Pilots will have good visual cues for approach and landing.
Bad: Gas turbine exhausts pointing down over the side may cause clouds of rising hot gas to envelop the helideck and helicopter approach path. This is particularly likely to happen in light wind conditions. If a shuttle tanker can connect to the stern of the FPSO, then the shuttle tanker may violate the helideck obstruction-free sector and the 5:1 falling gradient.
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本文链接地址：离岸直升机起落甲板设计指南 OFFSHORE HELIDECK DESIGN GUIDELINES 2(18)
