| 摘要 |
A self-supporting marker buoy includes an upper unit, a lower unit, and a rim-engaging cover. The upper unit is a frustum which further includes a base opening facing downwards, a hollow center, and a base rim around the base opening. The lower unit is an upside-down frustum, which further includes a top opening facing upwards, a hollow center, a top rim around the top opening, and a water entry at the bottom of the lower unit. The radius of the base opening of the upper unit is less than that of the top opening of the lower unit.
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