In many small sailing dinghies, the centreplate is housed in a centreplate case, and as it is pivoted it allows the centreplate to be lowed during sailing. The degree that the centreplate case is lowered has an impact of the sailing properties of the dinghies.
Having a slot through the bottom of the hull without a casing would cause problems, so the casing enables the plate to be surrounded by water up to the height of the waterline without sinking the boat!
There is a lot of skill required to fit these centreplate cases as they interact with many of the hull components (hog, ribs, central thwart, centreplate itself and its pivot). It needs to be strong, top level and of course watertight. The process is covered in the video and supported by photos.
The process is demonstrated in the accompanying video clips with a step-by-step guide. The conversation with the boat builder, in this case Marcus Lewis, is unscripted and covers the technique from his experience.