A keel also provides weight low under the water to lower the boat's center of gravity below the waterline, which is needed so that the boat bobs back upright if knocked over by wind or waves.

龙骨同时也增加了船只的底部重量，从而将船只重心降到吃水线之下，而这对于船只在被风浪打翻时能够得以及时回正是十分必要的。

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The advantage of a swing keel is that, with the keel raised, the sailboat can go into shallow water and sits lower on a trailer.

摇摆龙骨的优点在于，当龙骨升起时，船只能在浅水航行，并减低在拖车上的高度。

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Indirect materials including Aluminum Alloy keel or PVC keel, buckle strips, fasteners, adhesives, the relative direct cost of raw materials is slightly lower.

间接原材料包括铝合金龙骨或PVC龙骨、扣边条、固定件、粘结剂等，相对直接原材料费用稍低。

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Each robot is composed of two halves: the upper part, shaped like a stunted surfboard, is attached by a cable to a lower part that sports a series of fins and a keel.

BBC: PacX Wave Glide