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