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Design
Inputs & Controls - TBDP©
Version 8 |
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Here's the kind of () Design
controls you have available with TBDP©/VBDP© to help optimize your tunnel hull
and Vee hull performance…There's
a lot here, and still more in the program! [Screen Samples] [View and download sample TBDP© Design Input sheet]
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1. Boat Design Input [see Input Screen Sample]
| NAME |
UNITS |
DESCRIPTION |
| Hull
Design |
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| Tunnel
Height |
(In) |
Height
of the tunnel at the aftmost location, measured from the tunnel roof to
the aft sponson bottoms (running pads). |
| Vee Deck Ht |
(In) |
Height of the deck at the highest location, measured from the deck surface to the (virtual) water surface. |
| Tunnel Width |
(In) |
Width of tunnel,
measured from inside sponson to inside sponson. |
| Wing Chord |
(Ft) |
length of the
"wing" or aerofoil, measured from the leading (front) edge of
the deck to the trailing (aftmost) edge, |
| Vee AeroChord |
(Ft) |
Length of the Vee deck surface or
"wing"/aerofoil, measured from the leading (front) edge of the
deck to
the trailing (aftmost) edge. |
| WingThickness |
(In) |
Maximum thickness
of the aerofoil, measured from the top of the deck to the tunnel roof, at
the thickest point along the length. |
| Vee AeroThickness |
(In) |
Affects aerodynamic performance of vee
hull. Estimate as difference between height of deck fore -
minus height
of deck aft OR 10% of 'Vee Deck Ht'. [Also use 'Auto Vee Hull Wizard' for
estimate] |
| Sponson Type |
(select) |
Select whether design has a Symmetrical or Assymetrical sponson shapes |
| SponsonLength |
(ft) |
Maximum wetted Length of sponsons. Must be less than BoatLength and greater than zero. Default is BoatLength. Consider using only the length portion of sponsons that are ‘flat’ or are likely to contribute to Lift in normal applications. |
| Vee Hull Wet Length |
(ft) |
Maximum wetted Length of running surfaces. Must be less than BoatLength and greater than zero. Default is BoatLength. |
| Pad Width |
(In) |
Width of
(one) sponson running surfaces (bottoms), measured from sheer (inside) to
effective chine (outside). |
| Vee 1/2 Width |
(in) |
Width of 1/2 of vee section surfaces (bottoms), measured from effective sheer (inside) to effective chine (outside). |
| Pad Deadrise |
(Deg) |
Angle of sponson
running surfaces, measured from sheer to chine. |
| Vee Deadrise |
(Deg) |
Angle of vee running surfaces, measured from sheer to chine. |
| Deadrise Fore |
(Deg) |
Use for defining
variable deadrise angle. Value of deadrise angle (sponson pad or vee
surface) angle portion ahead of 'LengthToDeadriseFore' |
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LengthToDeadriseFore |
(ft) |
Use for defining
variable deadrise angle. Length forward of transom where 'Deadrise Fore'
angle begins. |
| Deck Width |
(In) |
Width of the hull
deck at the widest point. |
| Steps |
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| Step Select |
(Selection) |
Select the use of
sponson bottom design – no steps, one step, two steps |
| Step Length1 |
(Ft) |
Length of first (or
single) step fore of transom (in feet), must be less than boat length |
| Step Length2 |
(Ft) |
Length of second
step fore of first step (in feet), StepLength1 StepLength2 must be less
than boat length |
| Step Height |
(In) |
Height of
1st STEP in
sponson/vee running surface, if one exists. |
| Step2 Height |
(In) |
Height of
2nd STEP in
sponson/vee running surface, if exists. |
| Fore Step Angle |
(deg) |
Angle (degrees) of planing surface
foreward of foremost step (normally same as Step angle) |
| CenterPod |
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| CtrpodSelect |
(Selection) |
Select whether the
hull design includes a Mod-VP style CENTRE POD lifting surface (Yes/No)
Hint: If there is NO CENTRE POD in the design, then the design is a
conventional tunnel hull configuration, and NOT a Mod-VP design). |
| CtrpodLength |
(Ft) |
When it exists, the
length of Mod-VP style CENTRE POD lifting surface, located centrally in
the tunnel. This design feature generates additional hydrodynamic lifting
capability, increases stability. It adds water drag and reduces
aerodynamic lift. |
| PodWidth |
(In) |
Overall
width of CENTREPOD, from chine to chine. |
| PodHeight |
(In) |
Height difference
between SPONSON and CENTREPOD, positive means CENTREPOD is higher from
waterline than SPONSONS. |
| PodDeadrise |
(Deg) |
Angle of CENTREPOD
running surfaces (bottoms), measured from keel to chine. |
| Notched Center Pod |
(In) |
Length of
CenterPod notch forward of sponson pads trailing edge (enter '0' if same
location) |
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CenterPod Angle Increment |
(Deg) |
Incremental CenterPod Angle of attack relative to Sponsons ( /-). This feature is used when the angle of incidence of the CenterPod running surface is different than the angle of incidence for the sponson running surfaces (pads). (Some designs have the CenterPod at a slightly incrementally “higher” angle of incidence as compared to the sponson pads) |
| Vee Pad |
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| VeePadSelect |
(Selection) |
Select whether the hull design includes a Pad-Vee style CENTERPAD lifting surface (Yes/No) |
| VeePadLength |
(Ft) |
When it exists, the length of Pad-Vee style CENTER PAD lifting surface, located centrally in the hull. |
| VeePadWidth |
(In) |
Overall width of Pad-Vee style CENTERPAD, from chine to chine. |
| VeePadHeight |
(In) |
Height difference between Vee planing surfaces and Pad-Vee style CENTERPAD, positive means CENTREPAD is higher from waterline than Vee planing surfaces. |
| VeePadDeadrise |
(Deg) |
Angle of CENTREPAD running surfaces (bottoms), measured from keel to chine. |
| Notched Vee Pad |
(In) |
Length of VeePad
notch forward of Vee surface trailing edge (enter '0' if same location) |
| Input View |
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Show More Decimals |
(Check) |
Select this checkbox to show more decimal places
for input values. This format is helpful when used with small dimensions
(such as RC model designs). |
| Vee
Hull Advanced |
(Check) |
Some (advanced) Vee Hull input variables are
automatically calculated and are hidden from the input screens. (These
values include "NonVee Width", "VeeAeroChord", "VeeAeroThickness",
"VeeAeroType", "VeeAngleInc"). The Default values for all of these variables
are normally OK for most design/setups. You can view/change these Advanced
variables by clicking on the 'checkbox' for <Vee Hull Advanced> on Boat
Design (Input Screen #1). |
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2. Weight
& Measure Input [see Input Screen Sample]
| NAME |
UNITS |
DESCRIPTION |
| Lengths |
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| Boatlength |
(ft) |
Overall length of
hull, measured from sponson tips to aftmost deck or sponson point. |
| BoatCG |
(%) |
Location of static CG of boat only, measured as a % of total BoatLength ahead of transom (%). Default is 45% (0.45) of total BoatLength |
| Driverlength |
(ft) |
Location of the
driver, measured from the transom to the driver centre. |
| Motorlength |
(ft) |
Location of the
motor, measured from the transom to the motor centre. May be either fore
( ), or aft (-) of the transom. |
| Fuellength |
(ft) |
Location of the
fuel, measured from the transom to the fuel centre. |
| Misclength |
(ft) |
Location of
additional equipment that is concentrated mostly in one location, such as
hydraulic systems, ballast, etc., measured from the transom to the
(average) load centre. |
| Lower Unit
Length |
(ft) |
Distance of lower unit/drive
center fore/aft of the aftmost sponson/vee surface trailing edge. (Setback
on outboards, same as MotorLength on outboards, drive location for inboard
units). |
| Weights |
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| Boatweight |
(lbs) |
Total weight of
hull (only), including rigging, but excluding motor, fuel, driver, and
other significant additional equipment. This weight should include all
rigging weights that have not otherwise been accounted for. |
| Motorweight |
(lbs) |
Total weight of
motor, drive unit, propeller, and accessories such as hydraulic trims,
plates, etc that are attached to or built in at the motor. |
| Driverweight |
(lbs) |
Weight of driver
with all clothing and safety equipment. |
| Fuelweight |
(lbs) |
Weight of fuel
tanks and normal fuel supply. |
| Miscweight |
(lbs) |
weight of
additional concentrated equipment such as hydraulic systems, ballast,
etc., that are located at LENGTH MISC . |
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Outdrive Weight |
(lbs) |
Weight of outdrive unit(s) for IO or
Surface drives (does not apply to OB engines) |
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Motor Dimensions |
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| Motor Height |
(In) |
Height of MOTOR from water surface to
the top of the engine casing/housing. |
| LwrUnitHeight |
(In) |
Height of LOWER UNIT “Bullet”
above/below the sponson running pad surface. (+ is positive; - is
negative). This “height” or motor lift dimension affects MOTOR DRAG and the
moment force contributing to dynamic stability. [HINT: Most high performance
setups start with as little of the lower unit bullet in the water as
possible, thus reducing drag significantly. Surface piercing propellers and
low-level water pick-ups make this feasible. LwrUnitHeight values of +0.5in
to +1” (above sponson running surfaces) are possible in very high
performance applications. Without low water pickup, LwrUnitHeight values of
–0.5 to -2” (below sponson running surfaces) is applied]. |
| Height Motor Cowl |
(In) |
height of Motor Cowling from top of
deck surface to top of motor cowling |
| Width Motor Cowl |
(In) |
width of Motor Cowling |
| PowerMax |
(HP) |
shaft horsepower used as basis for all
OPTIMIZATION analyses. (NOTE that shaft HP is usually about 10% less than
the maximum power head HP on an outboard). Predictive performance solutions
will be based on this HP rating, within the specified solution tolerance
(ACCURACY DEF). Remember to include TOTAL HP of all engines in multiple
engine setups. |
| Lower Unit Trim |
(degrees) |
Incremental lower unit trim angle.
Generates Lift/Drag when not zero. (This is NOT the hull angle of attack
(Wangle). Use this feature with CAUTION). |
| Engine Spacing |
(in) |
Multi-engine spacing
(centerline-to-centerline) between engine outdrives. Affects lower
unit/drive drag. |
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3. Setup Tuning[see Input Screen Sample]
| NAME |
UNITS |
DESCRIPTION |
| Design Analysis |
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Optimization
Configuration |
(-) |
CALCULATION MODE SWITCH –
switch between the data entry mode and the OPTIMIZATION CONFIG mode.
CONFIGURED FOR VELOCITY OPTIMIZATION
- the program will find the maximum limiting velocity for the specified
Angle of Attack, while satisfying the specified power rating (POWER MAX). The
input value of STARTVEL will be used only as the first
"guesstimate" of the solution. If 'Auto 1-2-3' is
checked, then program will find the maximum limiting velocity for any Angle
of Attack. [Often used for the 'first run check' of potential design performance].
CONFIGURED FOR
ANGLE OPTIMIZATION - the program will find the optimum Angle of Attack
required to attain performance at the specified velocity, while satisfying
the specified power rating (POWER MAX). The predictive performance
solution will be presented for each of ten (10) specified velocities as
defined by STARTVEL and VELOCITY INCR'T. [Most powerful and used most frequently for performance evaluation, since this feature utilizes full power and minimizes the required trim angle to achieve balanced performance]
CONFIGURED FOR POWER OPTIMIZATION - the
program will find the required (minimum) POWER at the specified velocity,
for the specified Angle of Attack, as specified in the ACCEL MODEL. The predictive performance
solution will be presented for each of ten (10) specified velocities as
defined by STARTVEL and VELOCITY INCR'T. In addition, full power (POWER
MAX) will be used to estimate ACCELERATION rates and elapsed TIME to each
VELOCITY increment. This feature is a powerful tool in
evaluating detailed design and hull setup performance characteristics.
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| Auto 1-2-3
Performance Analysis |
(check) |
Just 'Check' the <1-2-3
Analysis> box for fully automatic 1-2-3 step performance analysis.
The Wizard guides you, step-by-step, through
the 3 helpful steps of Performance Analysis;
1. Maximum Limiting Velocity
2. WAngle (Trim Angles) is calculated using Maximum Power
3. Acceleration/Elapsed Time with specified WAngles (per ACCEL
MODEL), Required Power is calculated
When you initiate the <Calc Perform> analysis
button (on the top ToolBar) the Analysis Report Wizard will guide you
through each of the 3 steps of analysis, showing the Summary Results Report
for each step. |
| Extended
Analysis |
(check) |
Option to perform a “deep”
analysis for difficult situations. Can find more solutions, if needed, but will take
somewhat longer. Default is <not checked>. |
| Accuracy |
(%) |
Select allowable
tolerance of accuracy (%) for the OPTIMIZATION analysis, will define how close the
program iteration process will attempt to come to specified maximum power
rating, before displaying a solution; a smaller ACCURACY DEF gives higher
accuracy, but may take longer; too small an ACCURACY DEF may make it too
difficult to optimise a solution. (2% default) |
| Minimum Sponson Wet |
(In) |
Set minimum allowable sponson wetted length. Default is 0.01. Set to larger number to limit realistic wetted contact and unrealistically high velocities. |
| Minimum Vee Length Wet |
(in) |
Minimum allowable vee planing surface wetted length. Default is 0.01. Set to larger number to limit realistic wetted contact and unrealistically high velocities. |
| Start Velocity |
(Mph) |
Starting (lowest)
velocity of a series of ten (10) velocities that ANGLE OPTIMIZATION or
POWER OPTIMIZATION analyses will use. The predictive performance solutions
will be analysed for this velocity and the increasing velocities at
specified increments (VELOCITY INCREMENT). |
| Velocity Increment |
(Mph) |
increment used in
the series of ten (10) velocity steps analysed with ANGLE OPTIMIZATION or
POWER OPTIMIZATION analyses. Ineffective if VELOCITY OPTIMIZATION analysis
method is used. |
| Velocity Range
Wizard |
(Selection) |
[HELP
TOOL] You can use the Velocity Range Calculator
to automatically determine the incremental velocity steps to be used in
the analysis. Change any of the variables, and the others will be changed
automatically. Close the window to transfer the values back to the input
screen. |
| Start Angle |
(degrees) |
For ANGLE
OPTIMIZATION, this is used by the optimizing algorithms as a starting
estimate for the Angle of Attack of the running surfaces (sponson pads).
The program will find the angle of attack for the specified velocity while
still satisfying POWER MAX. The closer your first "guesstimate"
of ANGLESTART is to the optimum angle of attack (WANGLE), the faster the
optimising analysis procedure will be.For VELOCITY OPTIMIZATION, the
program uses this specified angle of attack to calculate the velocity that
will satisfy POWER MAX. For POWER OPTIMIZATION, the program uses this
specified angle of attack to calculate the POWER required to maintain
specified velocity increments, or it uses the WAngle input in the ACCEL
MODEL (see below). |
Acceleration
Model |
(selection) |
[HELP
TOOL] This is an optional input. The default
(Constant WAngle) is used for analysis if you don't change it. Input the
WAngle of attack for each Velocity in the performance range. For POWER
OPTIMIZATION, the program simulates acceleration and elapsed time based on
power available, and the WAngle of attack. Three (3) selections are
available:
(1) Constant WAngle: Uses the same WAngle for all velocities.
StartAngle input is used automatically. This gives a bounding simulation
of achievable acceleration.
(2) Straight-Line WAngle: A more realistic
acceleration and elapsed time simulation can be modelled by inputting a
specific WAngle for each Velocity in the performance range. A reasonable
representation of this WAngle is provided as a "Straight-Line"
increase of WAngle from zero (0 degrees) up to the input Startangle
(3)
User-Fit: A third simulation "User Fit" can be selelected,
allowing the user to input a specific WAngle of attack for each velocity
in the performance range. This will be most accurate, but is for advanced
users.
['FastAccel' is available with 'User Fit'
(Custom) WAngle option. 'FastAccel' button changes the WAngle of all
velocity steps to the maximum value. Specifying WAngles at the maximum
throughout the velocity range can maximize acceleration and minimize
'Elapsed Time' |
| Drive
Unit |
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| Drive Type |
(Selection) |
[HELP
TOOL] Select the type of lower unit (outdrive)
you are using, from a drop-down list of all manufacturers. All of
the dimensional detials (below) of the selected drive are automatically
input to the remaining fields, when you make your selection. You can
also select to input your own specific outdrive design dimensions. |
| Drive Number |
(Selection) |
The number of lower
unit drives (no. of engines). Select: One (default); Two or Three drive
units. |
| Skeg Width |
(In) |
average width of
motor lower unit/outdrive skeg (leading edge of skeg to back of skeg). |
| Skeg Length |
(In) |
length of motor
lower unit/outdrive skeg (top of skeg to bottom of skeg). |
| Skeg Thickness |
(In) |
thickness of motor
lower unit/outdrive skeg (thickness of the skeg plate). |
| Torpedo length |
(In) |
length of motor
lower unit/outdrive torpedo housing (leading edge of torpedo to aft edge
of torpedo, at prop shaft). |
| Torpedo diameter |
(In) |
diameter of motor
lower unit/outdrive torpedo housing (in section). |
| Gear Ratio |
(ratio) |
gear ratio of Lower
Unit/drive unit (input directly or from MotorSelection Wizard database). |
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4. Aero/Cockpit Input [see Input Screen Sample] |
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| NAME |
UNITS |
DESCRIPTION |
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AeroFoil |
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| Aerofoil
Type |
(Selection) |
Aerofoil design TYPE, or configuration. Can be selected from five (5) TYPE's: [performance data researched by AR®]
(1) Positive Camber - upper lift surface has a camber to positive (upward lift) side of aerofoil chord. This is the normal default tunnel boat aerofoil TYPE.
(2) Medium Camber - both upper and lower lift surfaces have camber to positive (lift) side of aerofoil chord. This can produce higher lift, but also more dynamic changes to aerofoil Centre of Pressure. This TYPE of aerofoil shape should be used with some caution, but can produce good results.
(3) High Camber - both upper and lower lift surfaces have camber to positive (lift) side of aerofoil chord. This can produce much higher lift, but also bigger dynamic changes to aerofoil Centre of Pressure. Also can generate significant interference with water surface and can cause EXTREME dynamic instability. This TYPE of aerofoil shape should be USED WITH CAUTION, but can produce excellent results when properly tuned-in.
(4) Zero Camber - upper lift surface has positive camber, lower lift surface has negative camber. When the amount of cambers are the same on both surfaces, aerofoil has what is called a zero camber. This generates less lift, but also less drag, and is somewhat more aerodynamically stable. It can create interference with water surface in some conditions.
(5) Low Camber - upper lift surface has positive camber, lower" lift
surface has slightly negative camber. This Aerofoil TYPE is often seen in
competitive designs, but is not particularly efficient. This TYPE generates
less lift than TYPE's with more" positive camber, and not that much less
drag. It is fairly aerodynamically stable, although can create interference
with water surface in some conditions. |
| AeroType Vee
Hull |
(Selection) |
AeroType for Vee hulls can be
selected from:
(1) Good Aero
(2) Some Aero
(3) Poor Aero
(4) Excellent Aero
(5) Very Good Aero
This selection affects the aerodynamic characteristics of the Vee hull deck
surface and hull surfaces, as they can influence aerodynamic Lift and Drag. |
| Angle Inc |
(Deg) |
Incremental angle
between running surface (sponson pads) and the wing chord. This is usually
the additional (if any) angle of attack of the wing chord compared to the
angle of the running surfaces (e.g. the angle of the wing chord if the
running surfaces were at an angle of zero). |
AngleInc
Calculator |
(Deg) |
[HELP
TOOL] You can use the AngleInc Calculator to automatically
determine the incremental angle of attack of your hull design. The
AngleInc is the difference in angle between the aerofoil chord and the
sponson bottoms (when sponsons are at zero angle). Input the height to
chord at the leading edge of the wing; and the height to chord at the
trailing edge of the wing; the Calculator will determine the incremental
angle. The calculated AngleInc will be automatically transferred to the
input field when you close the Calculator window |
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Cockpit/Cowling |
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| Cowl/Fairing
Type |
(Selection) |
Type of cowling or cockpit design,
either:
(1) OPEN faired front and rear cowlings, with exposed driver
cockpit.
(2) CANOPY type with integral or closed, faired cockpit
enclosure, like with a safety cell.
(3) NONE (no cowling) - open cockpit
with no fairings.
(4) COCKPIT-WINDSCREEN - open passenger cockpit with
windscreen/windshield as an aerodynamic break to airflow over the cockpit.
(5) WSCREEN WITH COVER or NONE WITH COVER – open cockpit with a type of
cover enclosing the open area.
(6) WSCREEN WITH REAR COWL or NONE WITH
REAR COWL - open cockpit with Rear Cowling/Fairing located in front of
outboard engine; reduces Motor Cowl aerodynamic drag (applies mostly to
outboard designs).
(7) STREAMLINED - open cockpit that is designed to
minimize air flow around appendages and driver/passengers. (Also STREAMLINE
WITH REAR COWL and STREAMLINED WITH COVER).
(8) CUDDY CABIN type for
covered open cockpit/passenger section.
(9) CENTER CONSOLE - open
cockpit with unprotected command/driver console. |
| Rear Cowl/Fairing
Height |
(in) |
Height of REAR COWL
from the deck surface to the maximum point above the deck surface. |
| Front Cowl/Screen
Height |
(in) |
Height of FRONT COWL or cockpit
or windscreen from the deck surface to the maximum point above the deck
surface |
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Cockpit Width |
(in) |
Width of COWL or COCKPIT at the
widest point |
| Cockpit Length |
(in) |
Length (fore/aft) of cockpit or cowling |
| # of Passengers |
(qty) |
Number of passengers in the airflow (for example if there
are 2 + 2 passengers (2 in front, 2 in rear) then the 'number of
passengers in air flow' is usually appropriately = 2.)
Sometimes there
can be a Passenger Appendage aerodynamic drag resulting from any portion of
passengers or payload that is in direct airflow. This depends on setup of
the cockpit, cowling and/or fairing designs and the height of hull deck
s, etc. TBDP©/VBDP© includes Passenger Appendage aero drag for the number
of passengers input.
This input value does not affect any other
calculations or analysis. The additional aerodynamic drag associated with
Passenger Appendage is included in the Performance Output variable, DCowl |
| Open/Clear
Fwd Deck |
(in) |
Length of open
(clear deck surface without obstructions) deck fore of the cockpit. |
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5. Design Details Input [see Input Screen Sample]
| NAME |
UNITS |
DESCRIPTION |
|
Operating Conditions |
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| Power Max |
(Hp) |
shaft horsepower
used as basis for all OPTIMIZATION analyses. (Note that shaft HP is
usually about 10% less than the maximum powerhead HP on an outboard).
Predictive performance solutions will be based on this HP rating, within
the specified solution tolerance (ACCURACY DEF). |
| PowerEff'yFac
(WIZARD) |
(%) |
[HELP TOOL]
Efficiency factor in the transmittal of POWER from prop shaft into
propulsive force.
This includes efficiency losses due to
gear/transmission/shafts, hull efficiency losses and
propeller
inefficiencies, and is usually between 0.5 --> 1.0. The efficiency factory
is essentially a
measure of the “effectiveness” that available power is
transmitted to the water as a propulsive
force causing acceleration. Use
the Power Efficiency Wizard to enter each efficiency/loss value.
Use
PowerEffy WIZARD to help determine the overall power eff'y loss from the
engine through drive to the propeller to the water. Enter your expected
1) propeller slip factor (%),
2) practical hull eff'y (%) losses,
3)
drive train efficiency (%) losses.
The PowerEffy WIZARD will compute
your overall PowerEfficiency and Effective Power Available. |
| RPM Max |
(RPM) |
Maximum RPM
setting/allowable on engine (input directly or from MotorSelection Wizard
database). |
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Air/Water |
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Altitude |
(ft) |
altitude above sea level, of expected
performance conditions. |
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Water Type |
(Selection) |
expected water
conditions - sea water or fresh water. |
| Air Temperature |
(deg) |
Air Ambient temperature (%)
(deg) |
| Air Humidity |
(%) |
Air Relative humidity |
| Water Temperature |
(deg) |
Water temperature |
| Lifting Strakes |
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| Lift Strakes |
(selection) |
Select “One Strake”, “Two
Strakes”, “Three Strakes” or “No Strakes”. TBDP©/VBDP© assumes that there
are Lift Strakes on both sides of hull (pairs); |
| Strake Location |
(in) |
Strake location dimension on
Vee Hull is specified as horizontal distance from centerline of hull; strake
location dimension on Tunnel Hull is specified as horizontal distance from
inside of sponson keelson. |
| Strake Width |
(in) |
Horizontal
width of Strake component |
| Spray Rails |
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| Above-Chine
Spray Rails |
(Selection) |
Check to turn ON, if your
design includes spray rail components located ABOVE the chine (ie: not on
planning surfaces). Use of above-chine spray rails can reduce sheer spray
drag on some hull configurations. |
| Below-Chine
Spray Rails |
(Selection) |
Check to turn ON, if your
design includes spray rail components located BELOW the chine (ie: on the
planning surfaces). Use of below-chine spray rails can reduce whisker-spray
drag on some hull configurations, if effectively sized and located. |
| Center Pod Spray
Rail |
(Selection) |
Check to turn ON, if your design
includes spray rail components on the Center Pod (Tunnel Hull).
Use of
spray rails can reduce whisker-spray drag on some hull configurations, if
effectively sized
and located. |
| Center Pad Spray
Rail |
(Selection) |
Check to
turn ON, if your design includes spray rail components on the Center Pad (Vee Hull). Use of spray rails can reduce whisker-spray drag on some hull configurations, if
effectively sized and located. |
| Spray Width |
(In) |
Width of SPRAY RAIL, if they
exist. |
| SprayFac |
(0->.99) |
Factor estimates effectiveness
of spray rail in redirecting any water spray. Higher value PREVENTS prevents more
spray drag. Affected by effectiveness of spray rails, chine steps,
etc. (Default = 0.5) |
| Trim
Tabs |
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| Trim Tab
Selection |
(Select) |
Select checkbox – check for use
of Trim Tabs; uncheck for NO Trim Tabs. TBDP©/VBDP© assumes that there are 2
Tabs for all installations (input dimensions are for each (1) Tab. |
| Tab Width |
(in) |
Horizontal width dimension of
each Trim Tab |
| Tab Length |
(in) |
Trailing Length dimension of
each Trim Tab |
| Tab Deflection |
(deg) |
Tab
Deflection (degrees, “+ve” input means deflected Tab DOWN to water; “-ve”
input means retracted Tab UP) |
| TTMaxVel |
(mph) |
Set the maximum velocity to turn off
(auto-retract) TrimTabs for safety |
| Suppress Warning |
- |
Check box to TURN OFF warning messages
regarding setup and safe operation of Trim Tabs. |
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13th edition
"Secrets
of Propeller Design" book!
