freeboard
freeboard — noun
1. The distance from the waterline to a vessel's main deck — or, on a small boat, t
The distance from the waterline to a vessel's main deck — or, on a small boat, to the gunwale. This height acts as a safety margin, preventing waves from washing over the side.
Pim checked the freeboard against the loading chart as the crew secured the last steel beam.
collocation: check the freeboard
The old fishing boat had so little freeboard that every wave wet the deck.
pattern: so little freeboard that...
Esteban measured the freeboard at the bow, where the water sat highest.
The cruise liner's generous freeboard kept the lower cabins dry during the storm.
Mei watched the freeboard shrink as the crew loaded more containers onto the ship.
- clearance
more general; can refer to any gap between two surfaces, not specifically maritime
- deck height
less technical term used in casual boating contexts, though less precise than freeboard
用法筆記
Used almost exclusively in maritime and naval contexts. When referring to small boats, freeboard is measured to the gunwale (the upper edge of the side), not to a deck.
常見錯誤
2. In structures built to hold back water — such as dams, levees, or flood walls —
In structures built to hold back water — such as dams, levees, or flood walls — the extra height added above the highest known water level. This margin ensures that waves or unexpected surges do not spill over the top.
Hugo designed the dam with two metres of freeboard above the highest flood level.
collocation: designed... with... freeboard
Engineers raised the reservoir wall by half a metre to add freeboard after new flood maps showed a higher risk.
collocation: raised... to add freeboard
Sahil measured the freeboard on the levee before the monsoon rains arrived.
The flood barrier's freeboard proved just enough when the river rose two metres overnight.
Tamar measured the dam's freeboard at three point two metres — well above the national safety minimum.
- overflow margin
used in some engineering documents but less common than freeboard in everyday practice
- safety height
broader term found in general safety regulations, not specific to water-retaining structures
用法筆記
Used in civil engineering and hydrology. Distinguish from sense 1 (SHIP CLEARANCE): this sense applies to dams, levees, and flood barriers, not to vessels or boats.