Hull and Structure Flashcards
AMI Systems Hull and Structure
Aft
An adjective or adverb meaning, towards the stern (rear) of the ship.
After Peak
Aftermost tank or compartment of a ship.
After Perpendicular
A line to the base line intersecting the after edge of the rudder post at the designed load water line. For stern counters that are well submerged, such as “cruiser sterns,” barges, and similar sterns. The after perpendicular is a line to the base line intersecting the after side of the stern counter at the designed load water line.
Air ports
Often referred to as side scuttles or port holes.
Amidship
The mid or center transverse plane of a vessel located midway between the forward and after perpendiculars.
Anchor
The purpose of the anchor gear or ground tackle is to secure a ship to the seabed in shallow water. Reasons for doing so can be the ship has to wait until a berth becomes available, to load or discharge cargo when a port does not have a berth alongside for the ship, to help with maneuvering in emergency to avoid grounding. In general, ships have two bow anchors and sometimes a stern anchor. There are two bow anchors for safety. Under normal circumstances, one anchor is sufficient, but under severe weather conditions or in a strong current both anchors may be needed. Also, if one anchor fails the second anchor is a backup.
Anchor Chain
An anchor chain is a chain connecting a ship to its anchor. The chain runs from the chain locker, through the Sperling pipe, via the gypsy wheel of the windlass, through the hawse pipe, to the anchor. The anchor chain consists of links with studs to prevent kinks in the chain (stud link chain).
Anode
Cathodic protection using a sacrificial material (usually zinc or aluminum). Intended to protect the Hull structure from corrosion.
Appendage
An underwater surface which protrudes from a hull. That’s to say any sort of keel, rudder, or skeg.
Athwartships or Transverse
Across the ship, at right angles to the keel.
Auxiliaries
Machinery other than main propulsive machinery.
Baffle
A plate or structure placed in the line of flow of fluids or gases to prevent the free flow in order to slow down or stop fluids from surging (e.g. oil tanks). Increases the stability and prevents the center of gravity moving when fluids shift from one side to another.
Ballast
Weight (usually sea water in tanks) loaded into a ship to increase stability when the ship is empty, or when cargo, etc., has a high vertical center of gravity. Also, used to control trim.
Base Line
Horizontal reference line, usually at the lowest boundary. For vessels with a flat keel plate outside of the bottom strakes, the base line is at the top of the flat keel. For vessels with a hanging bar keel, the base line is usually at the lower contour of the molded surface. For vessels with a designed trim or drag, the base line is at the lowest point.
Bilge
Rounded portion of hull between side and bottom.
Bilge Keel (or Rolling Chock)
A longitudinal member fitted to the outside of the shell on the bilge strake of plating to prevent excessive rolling of the ship.
Bitter End
The inboard end of a mooring line or anchor chain.
Bitts
A pair of short, vertical wooden or iron uprights for securing mooring or towing lines.
Bollard
An upright, somewhat stronger than a bitt, on a pier or wharf: used for mooring lines.
Boom
A term applied to a spar used in handling cargo.
Bow
The front of a vessel.
Bow Thruster
A motor driving a propeller near the bow that operates laterally to move the bow one way or the other to help with maneuvering.
Bracket
A steel plate, usually of triangular shape, and commonly with a reinforcing flange, used to stiffen or tie beam angles to bulkheads, frames to longitudinals, or any two structural parts which meet at an angle, in order to strengthen the joint against flexing.
Brow
A portable gangway or gangplank.
Bulbous Bow
A protruding bulb at the front of a ship that may be entirely underwater when the ship is fully loaded. A bulbous bow reduces the drag of a large ship underway by creating a wave of its own that partially negates the bow wave of the ship. This increases speed, fuel efficiency, stability, and the range of a large ship underway by as much as 15%.
Bulkhead
A partition between compartments. Transverse, extending athwartships. Longitudinal, extending fore-and-aft.
Bulkhead Deck
The uppermost deck to which watertight bulkheads are continuous.
Bulwark
The extension of a ship’s side above the level of the weather deck.
Buoyancy
An upward force exerted by a fluid, that opposes the weight of an immersed object.
Butts
The transverse joints in a vessel’s hull.
Camber
The transverse curvature of a deck.
Capstans
The capstan consists of a vertical warping drum with a vertical drive shaft that is driven either electrically, hydraulically, or electro-hydraulically. If the capstan is combined with a gypsy (or cat’s head) it can be used to control the anchor (i.e. a vertical anchor windlass).
Cavitation
A phenomenon in which rapid changes of pressure in a liquid lead to the formation of small vapor-filled cavities (or bubbles) in places where the pressure is relatively low.
Centerline
The fore-and-aft line at the middle of the ship.
Chain Locker
Chain lockers are high and narrow, making them self-stowing. This means that the stacked chain cannot fall over in bad weather. A chain locker is considered a confined space. The end of the chain, the bitter end, is secured to an end connection in the chain locker, with a release outside the locker.
Chock
A hole or ring attached to the hull to guide a line via that point; an opening in a ship’s bulwark, normally oval in shape, designed to allow mooring lines to be fastened to cleats or bits mounted to the ship’s deck.
Cleat
A cleat is a device used for securing a line used on a vessel for mooring purposes.
Coaming
The plates and shapes making up the boundaries of a hatch or skylight. Also, the piece between the deck and the lower skill of a doorway.
Cofferdam
The void space between two bulkheads or decks located close together used to isolate spaces from each other. Also called voids.
Collar
Filler plate used around a shape where it passes through plating for watertightness.
Collision Bulkhead
First complete watertight bulkhead from bow of shin.
Crane
Cranes are lifting devices on board Mobile Offshore Drilling Units (MODUs), Barges, Cargo and Tank vessels, and some Passenger vessels. Cranes are used to lift machinery, product service hoses, product, cargo and supplies.
Davit
Apparatus for lowering or raising lifeboats: a curved spar at the deck’s edge for hauling light loads.
Deadrise
The transverse angular rise of a vessel’s bottom from the base line measured at the vessel’s side.
Deadweight
The difference between a ship’s loaded and light displacement. Total deadweight refers to the carrying capacity of a ship’s cargo deadweight is total deadweight less fuel, water, stores, dunnage and other items necessary for use on the voyage.
Delamination
General term to describe when congruous laminate materials start to separate into layers.
Depth
The vertical measurement from the main deck at side to the base line or bottom of hull.
Displacement
The weight of water in long tons which a floating ship displaces. Light displacement is the weight of the ship with crew and ordinary stores aboard, but excluding cargo, fuel, and passengers. Loaded displacement is the weight of the ship at her maximum draft with crew, stores, cargo, fuel, and passengers.
Dogs
Closure fittings for watertight or weathertight doors and/or hatches.
Double Bottom
The space between the inner and outer bottom skins of a vessel.
Doubler Plate
A plate fitted outside or inside of another to give extra strength or stiffness.
Dry Dock
Any system that allows for a vessel to be taken out of the water for inspection or repair.
Ductility
The measure of steel’s ability to change its permanent shape without breaking. It is the opposite of brittleness. It is measured using a bend test.
Fairlead
A guide for the anchor line to run out so as to prevent it from fouling or snagging and keeps it pointed in the desired direction.
Fantail
The after end of the main deck.
Fathom
A six foot length.
Fender
Shock-absorbing device to protect a ship’s side from rubbing against a pier, another ship, or another object.
Flange
The turned edge of a plate or girder. A casting or forging at the end of a pipe to provide a connection.
Fluke
The part of an anchor that catches in the ground, especially the flat triangular piece at the end of each arm.
Fore Peak
A large compartment or tank just aft of the bow usually in the lower part of the ship, used for trimming the ship.
Forecastle
Elevated structure in the forward part of a vessel. Also, a merchant marine term meaning the crew’s living area or a seaman’s room. Sometimes referred to as “fo’csle.”
Forward Perpendicular
A line perpendicular to the base line and intersecting the forward side of the stem at designed load water line.
Frames
Built up ribs which give the ship strength transversely, supporting deck and shell plating. Vessels may also be of longitudinal frame construction with transverse web frames.
Freeboard
In general, the vertical distance from waterline to the top of weather deck at the side. Also, the distance to the lowest point of a watertight weather deck. Also, the Loadline Freeboard, which is the distance from the top of the deck at side amidships to the upper edge of the assigned loadline mark.
Freeing Port
An opening in the bulwarks, sometimes with a hinged flap, through which water can escape from the deck seaward.
Galvanic Corrosion
Corrosion that occurs when dissimilar metals are in close proximity and immersed in salt water.
Galvanizing
Process of coating metal with zinc to prevent rust.
Garboard Strake
The strake of shell plating next to the keel, not normally used for steel ship terminology.
Gudgeon
A socket at the stern of a vessel into which a rudder is fitted.
Gunwale
The line where an upper deck stringer intersects the shell. Also, the upper edge of the side of the boat.
Gusset
A triangular or square plate (bracket) lying in a horizontal or slightly included plane used for fastening beams, frames, stanchions, etc., to other structural members. In some vessels, a continuous fore-and-aft tie plate is used instead to avoid fitting numerous small gussets.
Gypsy (Cat’s Head)
The chain handling wheel is variously referred to as the gypsy. The wheels on either a vertical or horizontal windlass provide for either chain or line to be engaged.
Hatch
An opening in the deck to provide access to the ship’s hold.
Hawse Pipe
A large fitting extending from the deck through the side of the ship, near the bow, through which the anchor chain passes.
Hawser
A large line or heavy wire used for towing or mooring.
Heeling Moment
An expression of the power required to rotate or heel a vessel against its stability. Heeling moments can be caused by wind, by the centrifugal force in turning, by crowding of passengers on one side, by towing, or by the tension in the cable that links two vessels during operations at sea.
Hogging
Deformation of the ship when the middle portion is higher than the bow and stern. Reverse of sagging.
Hull
The body of a ship, including shell plating, framing, decks, bulkheads, stanchions, keel, and floors.
Intercostal
Between frames, not continuous.
Keel
The fore-and-aft member formed of long bars or flat plates end-to-end, extending from stem to stern on the centerline along the bottom of a ship.
Keelson, Vertical Keel
The vertical plate extending fore-and-aft located on the centerline and usually connected to the flat keel.
Lightning Holes
Holes cut in plates and frames to reduce weight and provide access holes.
Lightship
Weight of a fully equipped vessel that is unloaded (no fuel, water, cargo, or crew).
Limber Hole
A drain hole near the bottom of a floor.
Listing
A term to describe when a vessel tilts to one side. A ship can list either to port (left) or starboard (right). Could be caused from an imbalance in cargo stowage or a leak into a compartment.
Longitudinal
Any fore-and-aft structural member of a boat’s hull.
Malleability
The measure of a metal’s ability to withstand compression, such as hammering, rolling, or pressing.
Midship
Midway between forward and after perpendiculars. Also the centerline rudder position.
Non-Destructive Testing (NDT)
Inspection methods that allow inspectors to evaluate and collect data about a material, system, or component without permanently altering it.
Pad-eye
An eye, usually a piece of plate with a hole in it, attached to the ship for fastening cables.
Pintle
A pin or bolt, usually inserted into a gudgeon, which is used as part of a pivot or hinge.
Plating
The plates of the shell, decks, bulkheads, platforms, etc.
Port Side
The left-hand side of the vessel (when looking towards the Bow).
Rail
The upper edge of the bulwarks.
Reserve Buoyancy
The volume of air trapped in a watertight space (above) the waterline. The more you load a ship, the greater its “displacement” (the more it will sink in the water), the “less” reserve buoyancy it will have.
Rudder
A large fitting hinged to the rudder post or stock by which the ship is steered.
Sagging
Deformation of the ship when the middle portion is lower than the bow and stern. Reverse of hogging.
Scantlings
The dimensions, sizes and thicknesses of various parts of the ship.
Scupper
An opening in a deck or bulwark to allow water to run off the deck.
Seam
A term applied to an edge joint, usually refers to longitudinal joints.
Shackle
A U-shaped link with eyes worked in its ends and the open side closed by means of a pin inserted through the eyes.
Sheer Strake
The upper strake of shell plating, just below the bulwarks (at edge of deck).
Shell
The outside plating of a ship from stem to stern.
Skeg
The continuation of the keel which supports the heel of the rudder. In barges, attachments to the after Hull which act as a sort of stationary rudder to stabilize the movement of the barge through the water when towed. Barge skegs may be adjustable.
Sounding Pipe or Tube
Vertical pipe in oil or water tank used to measure depth of liquid in tank.
Spud
Used in lieu of an anchor. A steel shaft or through deck piling which is driven through the ground below the water. Provides stability to the vessel or barge. This is integrated into the construction of the vessel.
Spurling Pipe
A pipe that connects to the chain locker, from which the anchor chain emerges onto the deck (for larger ships).
Spurling Port
The top of the Spurling pipe.
Stanchion
An upright member used as a support or pillar.
Starboard
The right side of the vessel (when looking towards the Bow).
Stem
Forging, casting or structural steel forming extreme bow of ship extending from keel to uppermost deck.
Stern
The rear of a vessel.
Stern Tube
Tube in stern through which a propeller shaft passes.
Stiffener
An angle bar, T-bar, channel, flatbar, etc., used to stiffen and form a support for plating of a bulkhead, web frame, etc.
Strut
A heavy arm or brace. Supports the shaft underneath the Hull structure. The Strut also houses the Strut bearing which also provides lubrication for the turning shaft.
Swash Bulkhead
Non Tight bulkheads within tanks to give added strength to hull and act as baffles.
Tail Shaft
The aft section of the shaft which receives the propeller.
Tensile Strength
The measure of how much tension (stress) a material can resist before fracturing. It is mostly influenced by carbon content and heat treatment.
Transom
The cross section of the Stern (rear of the vessel).
Trimming
A term used to describe an imbalance in stability when a vessel tips forward (fore) or backward (aft).
Watertight Bulkhead
Designed and constructed to withstand a static head of water to the uppermost portion of the bulkhead.
Weathertight
A boundary that will not allow rain, sea spray, or water in any sea condition to penetrate the internals of a vessel.
Web Frames
Large transverse frames in longitudinally framed vessels located between bulkheads to support shell longitudinals and decks, and in transversely framed vessels where extra strength is needed.
Windlass
An anchor windlass is a machine that restrains and manipulates the anchor chain on a boat, allowing the anchor to be raised and lowered by means of chain cable. A notched wheel engages the links of the chain or the rope. Horizontal windlasses make use of an integral gearbox and motor assembly, all typically located above-deck, with a horizontal shaft through the unit and wheels for chain and/or rope on either side.
