III. RESULTADOS
3.1. LA EXPERIENCIA DE VIVIR EN UNA FAMILIA DE MADRE LESBIANA O PADRE GAY LESBIANA O PADRE GAY
3.1.1.5. Toma de conciencia en los casos de adopción
(5252 Hp) Hp = Horsepower Torque = ____________
Rpm Rpm = Revolutions per minute Propeller Horsepower Curve Formula
PHp = Csm Rpmn
Csm = sum matching constant
n= exponent from 2.2 to 3.0, with 2.7 being used for average boats Rpm = Revolutions per minute
Displacement Speed Formula
10.665 SL Ratio = ______
3____SHPLBWhere:
SL Ratio = Speed-Length Ratio and
SL Ratio = _____Knts
WL
Knts = Speed in knots = Boat speed or V SHP = Shaft Horsepower at propeller
LB = Displacement in pounds WL = Waterline length in feet
Displacement – Length Ratio Formula
disp T DL Ratio = ___________
(00.01XWL)3 Where:
disp T = Displacement in long tons of 2,240 pounds, mt = 1.016 long tons
WL = Waterline length in feet
Maximum Speed-Length Ratio vs DL Ratio Formula
SL Ratio = ______8.26 3.215
DL Ratio
Where:
SL = Speed-length ratio DL = Displacement-length ratio Crouch’s Planing Speed Formula
Knts = ________C Lb/SHP
Where:
Knts = Speed in knots = Boat Speed = V
C = Constant chosen for the type of vessel being considered LB = Displacement in pounds
SHP = Horsepower at the propeller shaft
The speed predicted by this formula assumes a propeller has been selected that gives between 50% and 60% efficiency, with 55% a good average.
Analysis Pitch Formula
101.33Va P0= ________
N0 Where:
Va = Speed in knots through wake at zero thrust N0 = Shaft Rpm at zero thrust
Theoretical Thrust Formula
Thrust = Force = F F = MA or F = __W (V0– V1)
g Where:
W = Weight in pounds the column of water accelerated astern by the propeller
g = the acceleration of gravity, 32.2 ft/sec.
V0= velocity of water before entering the propeller in feet per second V1= velocity of water after leaving propeller in feet per second M = Mass in slugs
A = Acceleration in feet per second squared Developed Area to Projected Area Formula
___ = 1.0125 – (0.1 PR) – (0.0625 PRAp 2) Ad
Where:
___ = Approximate ratio of projectedAp area to developed area Ad
PR = Pitch ratio of propeller Mean-Width Ratio Formula
Mean-Width Ratio = MWR Average Blade Width, MWR = ____________________ or
D
Expanded Area of One Blade MWR = ___________________________ ÷ D
Blade Height from Root to Tip Where:
D = Diameter
Disc-Area Ratio
πD2
Disc Area = ____ or 0.7854D2 4
Disc-Area Ratio = DAR Expanded Area of all Blades DAR = __________________________
Disc Area Where:
D = Diameter π ≈3.1412
Disc-Area Ratio vs Mean-Width Ratio
DAR = Number of Blades 0.51 MWR or
MWR = ________________________DAR Number of Blades 0.51 Where:
DAR = Disc-area ratio MWR = Mean-width Ratio
Note:These ratios assume a hub that is 20% of overall diameter, which is very close to average. Small propellers for pleasure craft may have slightly smaller hubs, while heavy, workboat propellers, particu-larly controllable-pitch propellers, may have slightly larger hubs.
Developed Area vs Disc-Area Ratio Formula
D 2 Ad = π __ DAR
(
2)
where for both the formulas on page 1-53:
Ad = Developed Area D = Diameter DAR = Disc-area ratio MWR = Mean-width ratio
π ≈3.1412
Developed Area for Any Hub Diameter and MWR Formula
Ad = MWR D (1 – Hub%) __ Number of BladesD2
or
D2
Ad = MWR __ (1 – Hub%) Number of Blades 2
Where:
Ad = Developed Area MWR = Mean-width ratio
D = Diameter
Hub% = Maximum hub diameter divided by overall diameter, D Blade-Thickness Fraction Formula
t0 BTF = __
D Where:
BTF = Blade-Thickness Fraction D = Diameter
t0= Maximum Blade Thickness as Extended to Shaft Centerline Rake Ratio Formula
___
Rake Ratio = ___BO D
Where:
___
BO = Distance between tip of blade projected down to the shaft cen-terline and face of blade extended down to shaft cencen-terline D = Diameter
Apparent Slip Formula
__ RPM – (Knts 101.3)P
(
12)
Slip A = __________________________
__ RPMP
(
12)
Which can be restated as:
Knts 1215.6 P = _________________
RPM (1 – Slip A) Where:
Slip A = Apparent Slip
P = Propeller face pitch in inches
Knts = Boat speed through the water or V in Knots RPM = Revolutions per minute of the propeller Slip vs Boat Speed Formula
Slip = _______1.4 Knts0.057 Where:
Knts = Boat speed in knots DIA-HP-RPM Formula
632.7 SHP0.2 D = ______________
RPM0.6
Optimum Pitch Ratio Formulas Average Pitch Ratio = 0.46 Knts0.26 Maximum Pitch Ratio = 0.52 Knts0.28 Minimum Pitch Ratio = 0.39 Knts0.23
These formulas have been found to check well with a wide variety of vessels.
Minimum Diameter Formula Dmin= 4.07 (BWL Hd)0.5
Dmin= Minimum acceptable propeller diameter in inches BWL = Beam on the waterline in feet
Hd= Draft of hull from the waterline down (excluding keel,skeg or deadwood) in feet
(Hull draft is the depth of the hull body to the fairbody line, rabbet, or the hull’s intersection with the top of the keel. It thus excludes keel and/or skeg.)
Dminfor twin screws = 0.8 Dmin
Dminfor triple screws = 0.65 Dmin
Allowable Blade Loading Formula PSI = 1.9 Va
0.5 Ft0.08 Where:
PSI = Pressure, in pounds per square inch, at which cavitation is likely to begin
Va= The speed of the water at the propeller in knots
Ft = The depth of immersion of the propeller shaft centerline, during operation, in feet
Actual Blade Loading Formula
326 SHP e PSI = _______________
Va Ad
Where:
PSI = Blade loading in pounds per square inches SHP = Shaft Horsepower at the propeller
e = Propeller efficiency in open water Va= Speed of water at the propeller, in knots
Ad = Developed area of propeller blades, in square inches Thrust Formula
326 SHP e TA = _______________
Va Where:
T = Thrust
SHP = Shaft Horsepower at the propeller e = Propeller efficiency
Va= Speed of water at the propeller, in knots Approximate Bollard Pull Formula
TsD= 62.72 (SHP __)0.67 12
Ts= Static thrust or bollard pull, in pounds SHP = Shaft Horsepower at the propeller
D = Propeller diameter in inches This formula can also be expressed as:
Tston = 0.028 (SHP Dft)0.67
Tston = Thrust in long tons of 2240 pounds SHP = Shaft Horsepower
Dft= Propeller diameter, in feet
Taylor Wake Fraction Formula
V – Va Wt = ______
V or
Va= V (1 – Wt) Where:
Wt = Taylor wake fraction
V = Boat speed through the water Va= Speed of the water at the propeller Wake Factor Formula
Wf = 1 – Wt Speed of Advance Formula
Va= V Wf Where:
V = Boat Speed Wf = Wake Factor
Wt = Taylor Wake Fraction
Wake Factor vs Block Coefficient Formulas for vessels with an SL Ratio of under 2.5
Single Screw Wf = 1.11 – (0.6 Cb) Twin Screw Wf = 10.6 – (0.4 Cb) Where:
Wf = Wake factor (percent of V “seen” by the propeller) Cb = Block coefficient of the hull
Block Coefficient Formula
Displacement
Cb = _____________________________
WL BWL Hd 64 Lb/cu.ft.
Where:
Displacement = Vessel displacement, in pounds WL = Waterline length, in feet
BWL = Waterline beam, in feet
Hd = Hull draft, excluding keel, skeg or deadwood, in feet Wake Factor vs Speed Formula
Wf = 0.83 Knts0.047 Where:
Wf = Wake Factor Knts = Speed in knots Power Factor Formula
(SHP)0.5 N Bp = ____________
Va2.5 Where:
Bp = Power Factor
SHP = Shaft Horsepower at the propeller N = Number of shaft revolutions
Va= Speed of advance of the propeller through the wake Advance Coefficient Formula
N Dft
= _______
Va
This may also be restated as:
= Va 12 D = ___________
N Where:
= Advance coefficient N = Shaft RPM
Dft= Propeller diameter in feet D = Propeller diameter in inches
Va= Speed of advance of the propeller through the wake Displacement Speed with Efficiency Formula
10.665 SL Ratio = ______
3____SHPLBWhere:
SL Ratio = Speed-length ratio LB = Displacement in pounds
SHP = Shaft horsepower at the propeller
= Propeller efficiency
If the speed in knots is already known, we can multiply the speed directly by
30.55____Planing Speed With Efficiency Formula Knts = ______C
____SHPLB 3____0.55 3____0.55Where:
Knts = Boat speed in knots LB = Displacement in pounds
SHP = Shaft horsepower at the propeller
= Propeller efficiency
If the speed in knots is already known, we can multiply the speed directly by
3____0.55Shaft Diameter Formula Solid Tobin Bronze Propeller Shafts
3 321000 SHP SFDs = ___________________
St RPM Ds = Shaft Diameter, in inches
SHP = Shaft Horsepower
SF = Safety factor (3 for yachts and light commercial craft, 5 to 8 for heavy commercial craft and racing boats)
St = Yield strength in torsional shear, in PSI RPM = Revolutions per minute of propeller shaft
Shaft Diameter Formula for Monel 400 Propeller Shafts
3 321000 SHP SFDs = ___________________ 0.80 St RPM
Ds = Shaft Diameter, in inches SHP = Shaft Horsepower
SF = Safety factor (3 for yachts and light commercial craft, 5 to 8 for heavy commercial craft and racing boats)
Shaft-Bearing Spacing Formula
3.21 Ds 4E Ft = __________ _____RPM Dens
Where:
Ft = Shaft-bearing spacing, in feet Ds = Propeller shaft diameter, in inches
RPM = Propeller shaft speed, in revolutions per minute E = Modulus of elasticity of shaft material, in PSI Dens = Density of shaft material, in pounds per cubic inch
Propeller Weight Formulas (with 0.33 mean width ratio and a hub diameter of 20%)
Three-Bladed Propeller Weight
Wgt = 0.00241 D3.05 Four-Bladed Propeller Weight
Wgt = 0.00323 D3.05 Where:
Wgt = Weight of propeller in pounds D = Diameter of propeller in inches
Brake Horsepower vs LOA Formula – Tugs
LOA4.15 BHP = 100 + _______
(
111000)
Where:
BHP = Maximum brake horsepower of engine LOA = Length overall of the tug at waterline, in feet Towing Speed vs Brake Horsepower Formula
Knts = 1.43 BHP0.21
Where:
Knts = Average speed in knots during average tow BHP = Maximum brake horsepower of engine D.W.T. of Barges Towed vs BHP Formulas
Low D.W.T. = (1.32 BHP) – 255.25 Avg D.W.T. = (3.43 BHP) – 599.18 High D.W.T. = (5.57 BHP) – 943.10 Where:
DWT = Deadweight tons of barges towed BHP = Maximum brake horsepower of engine