Load line and tonnage basics

46 CFR §175.122

Load lines. A vessel of 24 meters (79 feet) in length or more, the keel of which was laid or that was at a similar stage of construction on or after July 21, 1968, and that is on a voyage other than a domestic voyage is subject to load line assignment, certification, and marking under subchapter E (Load Lines) of this chapter. [CGD 85-080, 61 FR 947, Jan. 10, 1996, as amended by USCG-2014-0688, 79 FR 58288, Sept. 29, 2014]

46 CFR §185.602

Hull markings. (a) Each vessel must be marked as required by part 67, subpart I, of this chapter. (b) Paragraphs (c) through (g) of this section apply to each vessel that does not demonstrate compliance in accordance with § 178.310(c) of this chapter. (c) Each vessel must— (1) Have permanent draft marks at each end of the vessel; or (2) Have permanent loading marks placed on each side of the vessel forward and aft to indicate the maximum allowable trim and amidships to indicate the maximum allowable draft. (d) A loading mark required by paragraph (c)(2) of this section must be a horizontal line of at least 205 millimeters (8 inches) in length and 25 millimeters (1 inch) in height, with its upper edge passing through the point of maximum draft. The loading mark must be painted in a co…

NAVEDTRA 14057 Ch. 12 — Base Line

40 FEET DCf1211 15 TONS Figure 12-11. Vertical moment. It is obvious, then, that the volume of the submerged part of a floating ship provides the buoyancy to keep the ship afloat. If the ship is at rest, the buoyancy (which is the weight of the displaced water) must be equal to the weight of the ship. For this reason, the weight of a ship is generally referred to as DISPLACEMENT, meaning the weight of the volume of water displaced by the hull. Since weight (W) is equal to the displacement, it is possible to measure the volume of the underwater body (V) in cubic feet and multiply this volume by the weight of a cubic foot of seawater to determine what the ship weighs. This relationship may be written as the following: (1) W V 1 = × (2) V 35W= V = Volume of displaced seawater (in cubic feet)…

NAVEDTRA 14057 Ch. 12 — Review Questions

Q5. What measurement is known by the term freeboard? 1. Distance in feet from the keel to the waterline 2. Distance from the waterline to the weather deck edge 3. Distance from the bow to the stern 4. Distance from the portside to the starboard side of the ship Q6. Which of the following information is NOT contained in the “booklet of inclining experiment data?” 1. Data on displacement 2. The center of gravity above the keel 3. Reserve buoyancy 4. Overall stability • GM, metacentric height, is the distance from G to M; it is measured in feet. Z is the point at which a line, through G, parallel to the waterline, intersects the vertical line through B. • GZ, the distance from G to Z, is the ship’s righting arm; it is measured in feet. For small angles of heel, GZ may be expressed by the equ…

NAVEDTRA 14057 Ch. 12 — Waterline Displacement

28 FEET 24 FEET 20 FEET 16 FEET 18,000 TONS 14,800 TONS 11,750 TONS 8,800 TONS 5,900 TONS12 FEET Figure 12-13. Example of displacement data. Freeboard, a rough measure of reserve buoyancy, is the distance in feet from the waterline to the weather deck edge. Freeboard is calculated at the midship section. As indicated in figure 12-15, freeboard plus draft always equals the depth of the hull in feet. When weight is added to a ship, draft and displacement increase in the same amount freeboard and reserve buoyancy decrease. It is essential to the seaworthiness of a ship to retain a substantial amount of reserve buoyancy. Some ships can take more than their own weight in flooding water aboard without sinking due to reserve buoyancy. Center of Buoyancy When a ship is floating at rest in calm wa…

Boat Crew Seamanship Manual (M16114.5C) Ch. 20 — Heavy Weather Piw Recovery ¶3

Appendix A - Glossary TERM DEFINITION Beaufort Wind Scale A scale whose numbers define a particular state of wind and wave, allowing mariners to estimate the wind speed based on the sea state. Bell Buoy A floating aid to navigation with a short tower in which there are several clappers that strike the bell as it rocks with the motion of the sea. Below The space or spaces that are underneath a vessel’s main deck. Bilge The lowest point of a vessel’s inner hull, which is underwater. Bilge Alarm System An alarm for warning of excessive water or liquid in the bilge. Bilge Drain A drain used for removing water or liquid from the bilge. Bilge Pump A pump used to clear water or liquid from the bilge. Bitt A strong post of wood or metal, on deck in the bow or stern, to which anchor, mooring, or to…