46 C.F.R. § 178.450

Current through May 31, 2024

Section 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 * Basic 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 = (B_R * D_R) - V_R

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

D_R = total deck area of the cockpit or well deck in the after ²/₃ of the vessel length (LOD) measured in centimeters² (feet²).

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

Recess Ratio = L_R / L_C

L_R = the length of the recess in the after ²/₃ vessel length (LOD).

L_C= ²/₃ vessel length (LOD).

Weather Deck Volume = (B_D * D_D) - V_S

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

D_D = total deck area of the weather deck adjacent to bulwarks but not in way of the cockpit or well deck in the after ²/₃ of the vessel length (LOD) measured in centimenters² (feet²).

V_S = volume of any weather tight superstructure below the bulwark on the weather deck located within D_D.

Weather Deck Ratio = L_D / L_C

L_D = the length of the weather deck bulwark in the after ²/₃ of the vessel length (LOD).

L_C= ²/₃ 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.

46 C.F.R. §178.450

CGD 85-080, 61 FR 966, Jan. 10, 1996; 61 FR 20557, May 7, 1996; 88 FR 10032, Feb. 16, 2023

88 FR 10032, 2/16/2023