GSK - Ship´'s Construction Flashcards
Freeboard
Vertical distance at amidships between the uppermost continues watertight deck (Freeboard Deck) and the waterline
Assigned Freeboard
Vertical distance at amidships between uppermost continues watertight deck (Freeboard Deck) and the Summer Load line (SLL)
Freeboard Deck
Uppermost continues watertight deck having permanent means for closing all openings to maintain watertight integrity. Below which all openings in the vessel’s side have permanent means for watertight closure
Deck Girder
Supports the deck & secures the deck beams adding Longitudinal Strength to resist Hogging and Sagging
Pillar
Supports the deck beans transferring weight to the plate floor
Beam Knee
Supports the join between the deck beam and the transverse Frame;
resists Racking and helps to transfer the load from the deck into the frames
Deck Beam
Supports the deck and transfers the load from the deck into the transverse frames. Adds Transverse Strength to resit Racking
Transverse Frame
Ribs of the Ship giving support to the plating, deck and the deck beams as well as transferring the load to the bottom
Plate Floor
Vertical plates running across the ship transferring weight from the deck & Pillars to the Keel giving Transverse Strength.
It stiffens the bottoms plating and transfers weight of the ship to the surrounding water. Some have lightening holes to reduce the weight
Galvanic Corrosion
The Galvanic corrosion is a form of electrolysis whereby two different metals will react with one another to from an electric cell when they are placed in a suitable medium (an electrolyte).
In this case the less Nobel metal is aluminum which will give up its iron and become eaten away (it corrodes). The aluminum is known as the Anode while steel becomes the Cathode, The process is speed up due to the efficient salt water electrolyte.
- When on a hull with Propeller, use zink least nobel metal in galvancic scale as anode !!!
Sacrificial Anodes
ICCP Impressed current cathodic Protection
How does Chemical corrosion occur in steel?
What factors cause it to be accelerated and how Good ship design could reduce it?
Caused when the oxygen in the atmosphere combines with the metal and forms iron oxide. The oxide film is not firmly attached to the parent plate and thus permits further oxidation to occur.
Accelerated by:
water and heat
Prevented by:
good ventilation, reduce heat, avoid water traps, regular inspection and maintenance
What is Pounding ?
How can locality be stiffened to resist stress
Pounding is the vertical slamming of the Forefoot of the front of the Ship onto the trough of a wave being caused by a combination of pitching and heaving.
This Produces large impulsive forces on the bottom plating
- reduce frame spacing
- additional stiffeners introduced
- increase shell plating thickness
What is Panting?
How can locality be stiffened to resist stress
Panting is the In and Out movement of the shell material due to varying pressure changes.
The area is stiffened by:
- closer frame spacing
- increasing shell thickness
- thicker keel plate
- thicker plate stem
- additional Panting stringers
adding additional stiffeners (panting beams)
Items found in General Arrangement Plan
-Side elevation / Profile of decks
-tanks
-accomodation, bidgelayout
-alleyways, ladders
-Ships name
-Yard number
-storerooms
-general dimensions
-deckplan
Side Stringer
Horizontal longitudinal girder giving support to the frames & longitudinal strength to the structure
Side Girder
Supports the floors and gives longitudinal strength to the Ship reducing the effect of Hogging and Sagging
Task provided by Classification Society
-supervise the building process and ensure quality of work
-Construction rules
-materials specs
-surveyors available
-resale value
-offer insurance
Directions of Movement a vessel can experience
Yaw, Heave
Surge, roll
Sway and pitch
Hogging
Happens when ship is supported at amidships and not on bow and stern
draw