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# Electronic Code of Federal Regulations

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 e-CFR data is current as of September 17, 2020
 Title 46 → Chapter I → Subchapter T → Part 178 → Subpart D → §178.450

## §178.450   Calculation of drainage area for cockpit and well deck vessels.

(a) The drainage area required on a vessel must be computed using the following formula:

For protected waters required drainage = .1 × Basic Drainage

For partially protected waters required drainage = .5 × Basis Drainage

For exposed waters required drainage = Basic Drainage

where:

Basic Drainage area in centimeters2 = 4389.12 × [(Recess Volume × Recess Ratio) + (Weather Deck Volume × Weather Deck Ratio)]; or

Basic Drainage area in inch2 = (Recess Volume × Recess Ratio) + (Weather Deck Volume × Weather Deck Ratio)

Recess Volume = (BR × DR) − VR

BR = average height in centimeters (feet) of the bulwark above the well deck or cockpit deck;

DR = total deck area of the cockpit or well deck in the after 23 of the vessel length (LOD) measured in centimeters2 (feet2).

VR = volume of any weather tight structure below the bulwark of the well deck or cockpit deck.

Recess Ratio = LR / LC

LR = the length of the recess in the after 23 vessel length (LOD).

LC= 23 vessel length (LOD).

Weather Deck Volume = (BD × DD) − VS

BD = average height in centimeters (feet) of the bulwark above the weather deck;

DD = total deck area of the weather deck adjacent to bulwarks but not in way of the cockpit or well deck in the after 23 of the vessel length (LOD) measured in centimenters2 (feet2).

VS = volume of any weather tight superstructure below the bulwark on the weather deck located within DD.

Weather Deck Ratio = LD / LC

LD = the length of the weather deck bulwark in the after 23 of the vessel length (LOD).

LC= 23 vessel length (LOD).

(b) Vessels with bulwarks in the forward part of the vessel shall not form a well with the deckhouse which retains water.

[CGD 85-080, 61 FR 966, Jan. 10, 1996; 61 FR 20557, May 7, 1996]

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