Term
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Definition
load/area (tensile, compressive, shearing) |
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Term
ultimate tension for steel (tension & shear) |
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Definition
tension: 30 sq in shear: 22 sq in |
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Term
equation for bending moment (fixed beam) |
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Definition
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Term
equation for bending moment (concentrated load, unsupported ends) |
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Definition
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Term
equation for bending moment (uniform load, unsupported ends) |
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Definition
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Term
A _____ end beam will support _____ times the amount of load vs a _____ end beam |
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Definition
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Term
The deflection of a _____ ended rectangular beam is only _____ the deflection of a ____ ended beam |
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Definition
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Term
beam of equivalent size but made up of individual layers free to slip will only carry ____ the load of a solid beam |
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Definition
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Term
Relative strength equation (beams) |
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Definition
(D_larger/D_smaller)squared x original |
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Term
comparing deflection equation |
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Definition
(S_long/S_short)cubed, result x original deflection |
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Term
relative strength of beams |
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Definition
original length/new length x original load |
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Term
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Definition
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Term
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Definition
Length Overall; Linear distance from bow to stern, measured parallel to baseline |
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Term
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Definition
Longitudinal curvature of vessel's deck greater fwd than aft increases buoyancy w/ air space |
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Term
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Definition
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Term
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Definition
Width + projections (bridgewing, gangway, etc) |
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Term
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Definition
inward slope of the ships side measured widest beam less narrowest beam |
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Term
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Definition
opposite of tumblehome outward slope of ships side "dryer decks," throws waves from bow creates space/lessens impact force of water |
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Term
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Definition
vert distance from lowest part of hull to waterline indicated fwd aft amidships |
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Term
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Definition
distance from highest point to waterline important re: bridge clearances changes due to ballast |
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Term
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Definition
Transverse slope of deck directs water to drains at sides not specifically for added strength |
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Term
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Definition
Rise or slant up athwartship from bottom keel to bilge aka rise of the bottom / rise of the floor |
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Term
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Definition
vertical distance from the lowest point of the hull to the side of the deck to which it is referred depth = draft + freeboard |
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Term
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Definition
Dimensions taken from inside plating of a ship important for cargo stowage |
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Term
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Definition
distance measured vertically downard, at the side of vessel amidships, from upper edge of deckline to waterline |
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Term
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Definition
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Term
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Definition
mid-ship part of vessel where constant cross-sectional shape is maintained thru length. most merchant ships = parallel middle bodies, sides are vertical |
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Term
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Definition
immersed part of the hull fwd of middle body expensive to build cuz it's curvy |
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Term
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Definition
immersed part of hull aft of middle body where thrust is applied from prop where torque is applied from rudder |
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Term
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Definition
cheapest to build, hold most cargo |
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Term
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Definition
symbol for centerline plane |
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Term
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Definition
Used as an aid in locating points for design & building |
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Term
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Definition
established near base of ship runs thru upper edge of flat plate keel vert dims measured from this ref point |
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Term
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Definition
fore-aft (longitudinal) at right angles to BL hull shape essentially symmetrical on either side of CL |
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Term
Transverse Vertical Planes |
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Definition
at equal intervals along length of vessel aka frame stations may NOT be equal to actual frame locations |
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Term
Forward Perpendicular (FP) |
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Definition
line perpendicular to BL, intersecting the fwd edge of the stem at the design waterline |
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Term
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Definition
perpendicular to the baseline, intersecting the after end of the rudder post at the design waterline |
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Term
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Definition
center of ship (longitudinally), located at the midpoint between FP and AP |
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Term
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Definition
Length Between Perpendiculars measured parallel to BL |
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Term
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Definition
Average between fwd and aft drafts |
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Term
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Definition
mean draft compared to midship draft |
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Term
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Definition
mean draft is > mid ship draft (which is actual draft of vsl) |
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Term
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Definition
mean draft < midship draft (which is actual draft of vsl) |
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Term
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Definition
Hog/Sag caused by cargo load |
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Term
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Definition
Hog/Sag caused by crest & trough of wave under hull |
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Term
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Definition
Bottom of number is even top is + 6 inches middway is + 3 inches |
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Term
2 primary types of tonnage |
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Definition
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Term
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Definition
used to determine vsl earning capacity from 13 cen "tun" - wine cask equal to 100 cubic feet |
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Term
Volumetric tonnage determines... |
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Definition
port fees, dock fees, dry dock chgs idea is to base fees on ability to earn |
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Term
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Definition
entire volume of the inside of the hull from main deck down to keel |
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Term
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Definition
Remaining tonnage after non-earning spaces are removed from Gross ex tanks, foc'sle, psgr above main deck |
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Term
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Definition
Nominally water tight; no gasket secured via bolt hooks (old wood battens) allows for space deduction from gross |
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Term
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Definition
doublebottoms fore/aft peak if water ballast only poopdeck, bridge, foc'sle w/ tonnage openings |
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Term
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Definition
design machinery space btwn 13 & 20% of total gross tonnage and 32% may be deducted |
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Term
cubic ft required per crewman |
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Definition
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Term
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Definition
displacement tons deadweight tons lightship tonos |
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Term
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Definition
weight of water displaced by hull exactly equal to ships weight |
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Term
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Definition
amount of water cargo fuel and stores a vessel can carry fully loaded |
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Term
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Definition
weight of empty ship displacement of vessel w/ no cargo crew stores fuel water or ballast |
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Term
Lightship tons + deadweight tons = ? |
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Definition
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Term
volumetric tonnage: 1 ton = ? |
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Definition
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Term
weight tonnage: long ton short ton metric ton |
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Definition
long = 2240 pounds short = 2000 pounds metric = 2204.6 pounds (1,000 kg) |
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Term
4 general categories of steel items used in shipbuilding |
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Definition
beams plates columns shafts |
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Term
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Definition
coordinated functions of all 4 groups of steel used in shipbuilding |
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Term
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Definition
length from crest to crest = length of vsl height = 1/20 length of vessel use of wave this size determines max load on hull girdle & scantling requirements |
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Term
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Definition
total force acting on structure, usually expressed in pounds or tons |
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Term
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Definition
force per unit area, usually expressed in pounds/tons per square inch |
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Term
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Definition
distortion resulting from stress |
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Term
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Definition
occurs between 2 parts of a body when each draws the other end toward itself |
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Term
equation for tensile stress |
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Definition
Tensile Stress = Pull / Area Ts = P/A |
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Term
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Definition
opposite of tensile stress Cs = push/area |
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Term
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Definition
tendency of one body to slide over another body magnitude of this tendency at any point is termed shearing stress |
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Term
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Definition
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Term
Mild steel: ultimate tensile strength ultimate shearing strength |
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Definition
ult ts = 28-32 tons per sq inch ult ss = 22 tons per sq inch |
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Term
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Definition
compressed at about 18 tons per sq inch |
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Term
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Definition
point at which metal will no longer return to its original shape |
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Term
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Definition
metal hardens, slight additional weight stretches it out of proportion until reaches ultimate strength, then fails |
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Term
standard factor of safety |
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Definition
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Term
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Definition
strength of individual parts of the ship |
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Term
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Definition
strength of ship as a whole |
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Term
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Definition
A moment of a force about any line is the product of the force times the perpendicular distance to that line |
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Term
Bending moment: 100 lbs located 4' from end of board imbedded in a wall = |
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Definition
weight x distance 100 lbs x 4' = 400 ft-lbs |
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Term
Bending moment: 100 lbs located 8' from end of board imbedded in wall |
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Definition
BM = weight x distance BM = 100 lbs x 8' BM = 800 ft lbs |
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Term
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Definition
Horizontal strength members loaded vertically |
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Term
Load applied to center of beam causes... upper surface must be under... lower surface must be under... |
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Definition
...deflection ...compression ...tension |
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Term
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Definition
layer in deflected beam where compression & tension are neutral located along center of gravity (centroid) |
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Term
beam made up of 5 individual layers (versus solid beam) |
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Definition
will only carry 1/5 load vs solid top 2 will NOT be under compression bottom 2 will NOT be tension middle will NOT be nuetral |
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Term
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Definition
...determines resistance/strength. AKA larger distance from neutral axis to edges = stronger beam |
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Term
5 factors determine size of beam |
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Definition
1 type & amount of load on beam 2 distance btwn supports 3 type and efficiency of end connects 4 number of supports 5 material beam is made of |
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Term
type & efficiency of end connections |
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Definition
A) fixed-ended rectangular beam supports twice as much concentrated load as free ended B) deflection of fixed ended rect beam is 1/4th that of free ended |
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Term
effect of number of supports |
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Definition
greater # of supports in given distance equals shorter span. shorter span equals smaller bending moment. |
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Term
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Definition
most ship construction is mild grade steel other materials: stainless steel high tensile steel aluminum |
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Term
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Definition
strut placed such that it is loaded vertically (also referred to as stanchion or pillar) usually symmetrical (round) |
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Term
shafts subjected to twisting motion... |
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Definition
...said to be in torsion twisting moment = torque |
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Term
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Definition
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Term
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Definition
vessels must be constructed so that stresses may be graduallly and continuously dissipated no part over/undersized discontinuity or change in shape = stresses = failure |
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Term
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Definition
...fusion welding 6,000 degrees F usually electric arc, gas less common |
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Term
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Definition
...starts to replace other joining methods. By WWII it has replaced them almost completely. |
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Term
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Definition
main cause of cracks aboard ships. ex hatches, port openings, faulty welds |
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Term
secondary causes of fractures |
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Definition
low temp, unusually high bending moments, heavy seas |
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Term
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Definition
backbone. ties together transverse bottom members. absorbs large portions of stresses from hull girder action. |
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Term
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Definition
bar keel. flat plate keel. box keel. bilge keel. |
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Term
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Definition
olderships. protects when grounded. 1st pt contact. reduced rolling. disadvantages: increased draft no xtra cargo space. |
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Term
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Definition
utilizes increased shell plate thickness allowing it and components to better withstand dry docking /grounding loads. resembles i beam |
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Term
transverse bulkheads assist... |
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Definition
...in supporting keel and bottom by transforming long flexible girder into shorter length |
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Term
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Definition
act as conduit for wires/cables. allows access into other areas of double bottom. |
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Term
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Definition
fin like pieces of steel plate fitted to hull at turn of bilge along midship length . reduce rolling in heavy seas. NOT for stability. |
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Term
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Definition
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Term
Bottom structure acts as ________ |
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Definition
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Term
______ along with ________ acts to resist longitudinal stresses from passing over highs and lows of waves. |
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Definition
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Term
Bottom structure must be strong enough to withstand concentrated pressures due to _____, ____, and _____ |
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Definition
dry docking, grounding, weight of cargo |
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Term
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Definition
transverse vertical frames across bottom of hull; not equal to house floors |
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Term
5 features of ship floors |
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Definition
vertical transverse extend across ship from bilge to bilge usually at every frame (rib) |
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Term
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Definition
floors, deck beams, beam brackets, frames |
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Term
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Definition
structure formed by entire vessel (similar to duct keel) |
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Term
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Definition
closed, solid, open (bracket) |
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Term
4 features of closed floors |
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Definition
steel plating tank end members water/oil tight pierced by piping then seal welded |
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Term
3 features of solid floors |
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Definition
lightening holes air holes limber holes |
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Term
3 features of lightening holes |
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Definition
allow access (maitnc/inspection) reduce weight cut across neutral access |
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Term
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Definition
located at top of floor allow air to escape/enter during filling/emptying allow equalization of pressure |
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Term
limber holes purpose is... |
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Definition
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Term
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Definition
constructed from plain angle 25% lighter vs solid floors not allowed under mach spaces or areas subjected to heavy pounding loading/discharging |
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Term
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Definition
compartment at bottom of ship between inner bottom (tank top) and outer bottom; cellular like an ice cube tray |
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Term
advantages of double bottom vs single |
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Definition
stronger tanks can be used to carry fuel & ballast structure can withstand grounding and not flood holds/mach spaces as long as inner bottom remains intact better resists pollution |
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Term
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Definition
One of the ribs forming the skeleton of the ship |
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Term
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Definition
longitudinal version of floors (which are horizontal) |
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Term
Two primary types of framing |
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Definition
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Term
Large vessels (greater than 120 m) may be framed... |
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Definition
longitudinally framed on the bottom shell and transversely framed on the side shell. |
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Term
2 features of transverse framing |
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Definition
Act as stiffeners holding the side shell plating against external water pressure
Furnish vertical support to the outboard ends of the beams supporting the decks |
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Term
Transverse framing leads to greater or lesser number of frames within the hull? Frame spacing? |
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Definition
greater; spaced 2-3 feet apart (less at bow and stern for strength) |
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Term
Transverse framing maximizes ____ ____ capacity. |
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Definition
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|
Term
Advantages of Longitudinal Framing? |
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Definition
greater longitudinal strength, reduced vibration, weight savings, cost savings |
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Term
Disadvantages longitudinal framing? |
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Definition
loss of bale cubic due to depth of web frames |
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Term
longitudinals made from either _____ or ____ brackets welded to shell plating |
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Definition
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Term
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Definition
Additional framing in bow area to distribute the panting stresses encountered in seaway |
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Term
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Definition
Curved frame designed to accomodate the prop shaft and housing |
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Term
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Definition
keep water out tie together ship framework resist longitudinal bending stresses |
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Term
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Definition
shell plating arranged longitudinally, one plate after another in a row |
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Term
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Definition
flat plate rolled plate furnaced plate |
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Term
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Definition
curvature in only one direction most often @ turn of bilge |
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Term
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Definition
curvature in two directions must be heated and shaped over form most expensive; avoided as much as possible |
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Term
shell plates girth greater or lesser at mid ship than at ends? results in? |
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Definition
greater; results in excess plating at ends |
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Term
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Definition
when 2 rows of shell come together,top strake is dropped (called dropped strake), lower row remains (called through strake) |
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Term
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Definition
"new" single plate that butts up against drop strake and through strake |
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Term
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Definition
transverse joint between plates |
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Term
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Definition
longitudinal joint between plates |
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Term
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Definition
top strake that joins with deck plating |
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Term
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Definition
first strake after keel plate |
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Term
thickened plates (where)? |
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Definition
sheer strake, keel plates, bottom forward plates, bottom & bilge plates, margin plates, deck stringer |
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Term
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Definition
outboard most strake on deck |
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Term
on shell expansion plan, lettering runs from _____ and up, and numbering runs from _____ ______ |
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Definition
keel strake; from aft forward |
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Term
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Definition
athwart ship members located under deck plating |
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Term
Deck beams usually fitted.... |
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Definition
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Term
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Definition
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|
Term
frames carry load _____ , where it is distributed over the bottom by the ______. |
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Definition
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|
Term
3 primary functions of beams |
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Definition
act as beam to support vertical deck loads
acts as a tie to keep the sides of a shp in place
acts to keep the deck plating from wrinkling due to racking |
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Term
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Definition
twisting action on vessel as the ship sails at an angle to a heavy sea |
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Term
weather deck beams are of _____ scantling then would be used elsewhere |
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Definition
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|
Term
beam size depends on these other structural members of the vessel... |
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Definition
pillars girders thickness of plating height between deck |
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Term
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Definition
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Term
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Definition
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Term
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Definition
|
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Term
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Definition
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|
Term
What are the purpose of cant frames in steel vessels? |
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Definition
provide strength to shell plating at stern |
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Term
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Definition
a vertical strength member |
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|
Term
what are the synonyms for pillar? |
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Definition
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|
Term
why should pillars always be fitted in a vertical line? |
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Definition
To transmit load directly down to the keel, and not onto beams and deck plates. |
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Term
why is a pillar fitted under the windlass? |
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Definition
to absorb the stress, vibration, and weight of the windlass |
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Term
what is a partial bulkhead |
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Definition
bulkhead that does not extend across a compartment; used to strengthen the structure |
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Term
what three things does the size of a pillar depend on? |
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Definition
load, location, and length |
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Term
How does acceleration affect the size of the pillar? |
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Definition
dynamic load can be double the static load |
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Term
what is the purpose of deck girders? |
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Definition
support deck beams by reducing span |
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Term
why should pillars be well protected when cargo is loaded/unloaded? |
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Definition
to prevent damage, bent pillars provide little to no vertical support |
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Term
what is the purpose of wood sheathing |
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Definition
insulates - wood has low heat transmission absorbs damage and protects deck keeps outer decks cool for passengers prevents sweating due to rapid temp change under deck add aesthetic value to appearance of ship |
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Term
what is the purpose of the stringer plate? |
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Definition
thicker outboard plating to prevent racking and provide support for cargo hatchess |
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Term
why should corners of all hulls cut into the strength deck be rounded, doubled, or both? |
|
Definition
to prevent cracks and notches from forming due to stress |
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|
Term
differentiate between side stringer, girder, and longitudinal |
|
Definition
side stringer: longitudinal strength member inside deck plating longitudinal: fore and aft strength members in bottom structure girder: fore and aft longitudinal strength members supporting decks |
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Term
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Definition
provide additional vertical support & act as structural diaphragms to resist racking create fire & flooding boundaries |
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|
Term
what is a 2 compartment ship? |
|
Definition
A ship that can be flooded in 2 compartments and stay afloat |
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Term
max number of passengers a merchant ship can carry without being considered a passenger vessel? |
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Definition
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|
Term
what is the maximum distance the collision bulkhead can be from the stem? |
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Definition
1/20th the vessel length at summer load line |
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Term
what are the functions of the stem? |
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Definition
vertical extension of the keel gives strength and rigidity to hull along center-line ties shell plating gives rigidity to entire bow |
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|
Term
advantages of a clipper bow? |
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Definition
additional space and buoyancy flare throws water away from bow when headed into heavy seas |
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|
Term
what is the function of the stern frame? |
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Definition
vertical extension of the keel provides strength for rudder and single prop ties shell plating together at stern |
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|
Term
pillars give vertical support to... |
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Definition
girders deck beams decks heavy concentrated loads: ground tackle, anchor windlass, line handling winches, capstains |
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|
Term
why place pillar under deck beam or girder? |
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Definition
redices deflection by reducing span relieves stress on beam brackets & transverse frames |
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|
Term
top/bottom of pillar (names)? |
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Definition
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|
Term
purpose of doubling plate at bottom of pillars? |
|
Definition
to spread the load over larger portion of deck plating |
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|
Term
ideal depth of beam brackets |
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Definition
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|
Term
|
Definition
increases seaworthiness by forming watertight top of hull and contributes strength by acting as upper flange of hull girder |
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Term
|
Definition
working platforms for operation of machinery and loading of cargo living spaces for passengers and crew |
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|
Term
Additional purpose of all decks |
|
Definition
serve as horizontal diaphram, keeping the ship in shape longitudinally |
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|
Term
Girder stress concentration? |
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Definition
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|
Term
2 methods of insulation on ships? |
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Definition
insulation bats fixed to underside of deck via wire studs spray on insulation applied directly to steel deck |
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Term
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Definition
insulate space prevent sweating noise barrier in engine room decks and bulkheads on passenger vessels |
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Term
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Definition
paint cement composite that flexes with deck carpet, tile or linoleum over top of cement composite |
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Term
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Definition
flat plate steel or corrugated (adds strength, reduces need for additional framing) |
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Term
|
Definition
acts as auxiliary watertight bow in event actual bow is punctured in collision |
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Term
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Definition
encloses shaft in watertight compartment required on all screw type vessels prevents broken prop shaft from flooding aft section of vessel |
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|
Term
machinery space bulkheads |
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Definition
enclose machinery spaces - watertight regulatory requirement due to large through-hulls in engine rooms |
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|
Term
3 bulkheads required by regulation |
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Definition
collision bulkhead afterpeak bulkhead machinery space bulkhead |
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Term
Bulkheads are usually plated... |
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Definition
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|
Term
plate thickness thicker towards the bottom of the ship.. |
|
Definition
due to increased water pressure |
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|
Term
Why are longitudinal bulkheads avoided |
|
Definition
danger of capsizing due to collision and flooding of one side of the ship but they are seen in tankers |
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|
Term
longitudinal bulkheads in tankers |
|
Definition
single hull: port and starboard longitudinal bulkheads form boundaries between port, center, and stbd tanks double hull: usually only centerline longitudinal bulkhead |
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|
Term
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Definition
|
|
Term
|
Definition
straight up and down classic passenger ship, aided with riveted construction |
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Term
|
Definition
flared bow, extra space and buoyancy, throws water when headed into seas |
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Term
|
Definition
ice breaker, allows bow to ride up on ice and break it with the weight of the vessel |
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Term
|
Definition
curved connection between stem and keel sometimes cast |
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Term
|
Definition
lower stem section joining forefoot to upper stem |
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|
Term
|
Definition
plate heated and rolled to form plating around upper stem |
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Term
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Definition
triangular plate that joins plating and reinforces the solid stem bar |
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Term
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Definition
located forward of collision bulkhead serves as forwardmost ballast tank exerts greatest moment for trim changes, good for lessening sag |
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|
Term
components of forepeak tank |
|
Definition
valves and piping reach rods to open and close valves swash bulkheads reduce wave motion, can be longitudinally or transverse (generally longitudinal) |
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|
Term
Bulbous bow - what vessel speed? |
|
Definition
higher vessel speed - improves vessel flow through water, overcomes wave making resistance acts to fill in trough of bow wave = less power needed to reach medium/high speed |
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|
Term
two primary types of sterns |
|
Definition
cruiser: rounded, requires cant frames and beams to make curve. older construction transom: flat, modern construction cuz its cheaper, and waterline is carried further aft |
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