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SCT User Guide, scantlings with ISO 12215

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SCT_MC
SMALL CRAFT. - SCANTLINGS
International ISO Standard 12215-5 : 2019
May 2022
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SCT_MC
CHAPTER
Pag.
Introduction
1
Scantlings
3
Data Introduction
4
Getting Help
5
Defining the Structure
6
Work procedure
9
Materials Definition
11
Outputs in MS Word
12
_
INTRODUCTION
SCT_MC is an application that tries to help the designer with scantling of small craft, according the
ISO Standard 12215-5 : 2019, inside the scope defined by this standard.
The initial window of the application looks as follow :
It is a window of the called type “MDI” (multiple document interface), which acts as a container for several
other windows, called secondary windows, than the User can open along the same working session.
This window has its own heading menus , as we will see later, but, when one of the secondary windows
becomes the “active window”, the main window will only show the secondary window menus.
For this reason, in order to access to the MDI window’s menus, any other active windows must be closed.
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HEADER’S MENUS
Files menu
New Study: opens a secondary Windows to get the directory,
identification and any other data for the new study.
Open Existing Projects : opens a dialog box with the Windows
Explorer directory tree, to allow the designer to look for any
existing project, and load its data.
Save As : the user is asked for the new name and the
current project will be saved with that name, the program
creating the necessary folders.
Last projects : shows up to the 5 last projects we have been
dealing with. By clicking on its name, the application will load its
data and the window “Scantlings” will be open.
Delete History : deletes the list (not the projects) with the last
used projects.
Exit . Closes the application
Preferences menu
Language : allows the User to select
the language to be used by the
application.
Always start with Scantlings : when
checked this option, the window
“Scantlings” will automatically be shown
when starting a new work session.
Change Window Picture : allows to select a new image for the Background of the MDI window.
Delete Window Picture : no image will appear
REMARK : Options selected with the menu “Preferences” are saved by the application, that will
remember them while not further changes.
The window “Scantlings” has its own menu “Preferences”, that IS DIFFERENT THAN the one we have
just described, allowing the User to select specific preferences for working in scantlings.
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Other modules in menu
Accesses calculation
application:
modules
of
the
Materials : Open the window to work, modify
or add, materials.
Scantlings : Opens the window to work with
scantlings properly.
Structural arrangements …. (ISO 12215-6) :
opens the specific module for longitudinal
strength studies, protective keel, etc.
Rudders (ISO 12215-8) : rudders calculation
Welding : welding calculation for all the
structure elements, according ISO 12215-6.
Mast & Rigging : All calculations related to
the rigging. This module is sold
separately from SCT_MC, but once
installed, both applications are integrated.
Calculation of Beams : opens the modulus
to calculate frames and continuous beams.
Help menu
o
SCT_MC User Manual in pdf format.
o
Open the window to start the
application’s activation process.
o
SCT_MC , dealer and developer data
There may be some incompatibility with the pdf file reader. Therefore the help files are also in
.doc format and can be opened with MS Word.
All help files are stored in the folder .... SCT_MC \ Files \ AyudasSCTEn
.
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SCANTLINGS
The window to work with scantlings looks like in the image, with two differentiate areas :

The left one shows all the elements forming the structure of the ship.

The right hand area relates the properties of any of the precedent elements, as well as the results
when applying them the ISO Standard 12215-5 : 2019.
Clicking with the left button of the mouse over any one of the nodes in the left tree, the table in the right
side will show its properties.
Selecting any element in the window with the mouse left
button and, then, clicking on the right button, several popup menus will appear, helping the User in some tasks as :

Entering new data

Modifying existing data

Adding elements

Explanations about required data : menu “What is
this?” (see image)

Etc.
The total amount of nodes, elements, in the left hand tree is unlimited. However, as every node needs to
be linked to a table with its properties, the memory used can be very high and calculations speed may be
affected.
Within a complex project the number of nodes can become very high. That’s why, in order to avoid
so that we can know that the properties in the
confusion, the selected node will appear with the mark
right hand table are its properties.
On the other hand, if no node is marked with that icon, and we ask the application to do any calculation,
we could get improper or not coherent results.
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DATA INTRODUCTION
The introduction of data, an always convoluted task in this kind of studies, has been fully simplified.
Just we need to click, with the mouse left button, over the row which data we need to introduce :

In many cases, there is no other solution that do it manually. By clicking on the specific row, the
box will change its color and format. Now we can introduce or change the data.
The old data
will be shown
here

When possible,
relevant option.
SCT_MC opens several dropdown boxes where we just need to select the
Units used by the Standard are not fully homogeneous. For example :

The major (minor) dimension for a bulkhead’s panel must be in millimeters, while the load height
for it has to be given in meters.

The stiffeners spacing for a panel is given in millimeters, while its distance from the App is to be
given in meters.
 Etc.
For this reason, the label in the left of the text box, shows not only the item to be introduced but also its
correct units.
Besides of these facilities, not all the boxes in the table are to be fulfilled by the User, either because they
are not necessary for the calculation or because the application will deduce them from other previously
given data.
By instance, once introduced the waterline length, in fully loaded condition, and the vessel speed, SCT
will calculate the coefficient V/
and will deduce if the ship is “Displacement” or “Planning” type. The
boxes for these elements are marked with “---“ : we don’t need to fulfill them.
In other cases, the element in the table (that is extracted from a generic template) is not applicable to the
current item. The application, then, will write “n.a.” in its box : not applicable.
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GETTING HELP
There are two ways to get help :
1. At the top left of the window, among several other menus, is the one
labelled Help.
By clicking on it, a secondary window will appear with a list with the
different available help topics.
Pressing in the left area, over the required item, the right hand area will show appropriate
explanations. They are, usually, existing figures in the ISO Standard 12215-5.
2. Pressing in the main window over a node, label or box, firstly with the mouse left button and,
then, with the right button, the What is This? pop-up menu will appear.
Clicking on it, appropriate explanations will be shown to the User. Sometimes the application will
indicate that does not exist such explanation, well because it is obvious or because we just have
to choose among the possibilities listed in a dropdown box, making unnecessary more details.
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DEFINING THE STRUCTURE
The application shows a tree, similar to the one in the figure, with
the different areas that a generic new project needs.
We have, also, to define the plates an stringers needed to build
any element of the structure..
And, of course, we need some general data defining the overall
ship.
In this area, left part of the program’s window, we don’t need to
write anything. Everything works by means of pop-up menus
appearing when selecting a node and clicking, then, the right
button of the mouse.
It is possible to add or delete elements, or change their names.
Every AREA can have as many elements, with
different designations, as we consider necessary to
fully define the ship’s structure and fully study its
possible problems (see image) .
First thing the application will do, when trying to add a
new element, is asking us for a name for the item, so to
give it an unequivocal identification.
Every possible element is considered to be formed by a
plate panel, with transversal and longitudinal stiffeners
(vertical and horizontal for vertical elements of the
structure).
Although some of them will not be necessary, it does
not matter as we will not fill in the boxes in the table and
no calculations will be performed about them.
Those panels and stringers must be one of the
previously defined in the upper part of the nodes tree,
called “Plates and Stiffeners”.
Example : The bottom panel Central will be formed by
the Hand laminated of 8 mm thick and as stringers we’ll
use the Omega de 60x50x150, for frames, and Omega
de 40x40x60, for longitudinal.
We will see later how to assign a plate or a stiffeners to
each element in the structure.
In turn, when defining plates and stiffeners, we will have
to specify the material they are made with, as well as
the thickness, in case of plates.
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When PRF materials, SCT_MC calculates the thickness and other properties, depending on the mass
content of fiber we have indicated for each layer.
When defining stiffeners we have to indicate the profile type : flat bar, bulb bar, composed “T”, omega
profile, etc. and to give the dimensions.
You also may apply "hybrid" materials, combination
of
o
o
o
Glass / Carbon,
Glass / aramid or
Carbon / Aramid
When working with a plate, the following window will
be shown :
There you need to give an ID for the plate, select its
material
and then press Validate
Initially cells in white do not contains any data and they have to be filled in, as previously indicated, acting
over the boxes in grey color, mouse left button and/or right button.
For homogeneous materials we need to give the thickness but, when PRF materials the application will
include several additional rows, to introduce the materials of each of the layers that make up the laminate
of this plate or stiffener.
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1.
Pick the corresponding row with the left mouse button..
2.
Act over the right mouse button : a pop-up menu will appear and
we will select the option “Add laminate”.
SCT_MC
_
3.
Over the selected row will appear a dropdown box with several
available elements.
4.
Selecting one of then it will be incorporated in the actual row.
And so on till complete all the plies needed for the laminate
.
When selecting a hybrid material for a plate, the dropdown
list above will show elements of the two materials forming the
hybrid
There exists the option of Copy a Previous Combination
combination in a previous panel .

When choosing this option, a dropdown box appears
with the list of existing panels.

Selecting one of them, its mats-rovs will be copied in
the actual table, starting with the row we have pickedup first (see point 1)
Once this has be done, we press the button
Physical properties of the current plate will be calculated and the application will write them in the boxes
of the table, without any additional action from our side. These properties will be taken into account at the
moment of analyze the panels forming the structure.
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Working with a stiffener the procedure is very similar
The program presents a new window in which, in addition to identifying the stiffener and determining its
material, we can choose the type of profile that we need to use.
Depending on the type chosen, we will have to give the dimensions of its elements.
Once all this is done, press "Validate"
When dealing with PRF, the composition for the laminate has to be indicated.
In the case of "top hat" type reinforcements, it is
possible to add extra layers only in the crown,
which is the area where the stress due to bending
will reach its highest value. This makes it possible
to reinforce the crown without adding material, not
very efficient, to the "legs" of the reinforcement.
To do this, the option "... only crown" appears in
the dropdown box for each of the various layers
that form the laminate of the reinforcement.
_
WORKING PROCEDURE
As it can be deduct from the precedent, the normal working procedure would be as follow :
1. DEFINITION

Introduction of the general data for the boat

Determine the composition of each plate or stiffener that we are going to use for the panels or
reinforcements of the structure.

Delimit each of the well-differentiated areas into which the boat is divided.

In each area we will select one or more panels, with their corresponding reinforcements, to be studied.

Assign a plate and specific reinforcements to the elements that make up and limit each panel..
2.- CALCULATION
Once all dimensions have been defined as well as the
position of every element in the structure, the application will
deduce the real properties for everyone, and comparing
them with the ISO Standard 12215.-5 requirements.
These requirements will appear on the fourth column of the
table, marking with red color those properties below the
requirements.
3.- CHECK
Looking at the results we can decide the convenience or not of modifying elements properties, spacing of
stiffeners, the plate assigned to each panel, etc
4.- STACK ANALYSIS
When the "Enhanced" analysis method has been selected,
the stress analysis must be carried out in each layer of the
laminate to verify that, in none of them, the design stresses
of the material of that layer are exceeded.
The application carries out this task with when clicking on the
toolbars button illustrated in annexed figure. Note that this
study
is only possible if it has previously been carried out point #2.
On a template, specially prepared for this purpose in MS
Excel, and fully similar to the one showed in the ISO Standard 12215-5:2019 , will be arranged the
results of the analysis.
Any amount of analysis can be performed and all of them will be added into a single Excel file.
5.- SAVE STUDY
It is very convenient to save work with some
frequency in order to don not loose any one
of the calculations.
_
6.- OUTPUTS
The button in the toolbar of the
Scantling window creates a
document in MS Word with the
data introduced for the study, the
table properties for each element
as well as the results for them.
Writing in Word is a slow procedure
and, given that the structure may
have a lot of components, it may
last several minutes.
In the calculations the application uses several
pressures and coefficients that can be displayed
in a separate window, if we click on the figure.
The final report with results in MS Word also
displays these values.
STACK ANALYSIS The ply analysis for each panel or stiffener are shown directly in an Excel Work Sheet
specifically prepared for this study.
You can access the existing studies using the button
_
DEFINITION OF MATERIALS
This issue deserves a separate chapter and, in fact, the application has a
specific window to deal with them. Use the header menu “Materials”.
On the window’s left part, a nodes
tree shows all the materials existing
in the actual SCT_MC’s data base.
The table on the right part shows the
physical or mechanical properties for
the specific material selected on the
nodes tree.
SCT_MC
incorporates
a
collection of materials that will
probably be enough for most of the
options we will need in our projects.
If an
specific material were not
found, one could use a similar one
from those existing in the database or
incorporate a new material to it.
When adding a new material, it is necessary to introduce all its mechanical properties. In the case of PRF,
however, you only need to enter a few characteristics and the application will calculate the mechanical
properties, based on the formulas in Annex C of ISO 12215-5: 2019. The application colors the cells that must
be filled in by the user.
In this, and in other cases, cells with the text "---" appear. That means that these data, although necessary,
should not be filled in by the User, but rather the application will take care of it. However, if the User wishes to
enter a specific value by hand, they can do so, although it is not recommended.
_
VERY IMPORTANT NOTE
The SCT_MC database contains all the materials (steel, aluminum and wood) indicated in ISO
12215-5: 2019, with the physical and mechanical properties indicated there.
Regarding the properties of fiberglass and carbon materials, they have been calculated in
accordance with the indications and formulas of ANNEX C of ISO 12215-5: 2019.
For Aramid fibers, the formulas of ISO 12215-5: 2008 have been used.
Following the new version of the standard, to determine the properties of a laminate, some
variables that were not considered in the previous standard must be taken into account:

properties of the matrix used.

overal procedure for scantling determination (replaces the "Evaluation Level" of the
previous version.

Building quality, which aims to take into account the builder's expertise and quality.
The properties of the laminates in the plates section are calculated with certain values for these
parameters. In this way the designer can get an idea of the resistance of the materials that he is
going to use.
It may happen, however, that, when assigning these materials to a specific panel or reinforcement,
those variables are different from those initially foreseen. Or it may happen that elements that use
the same laminate scheme have different values of these variables.
For this reason, when assigning, for example, a plate to a certain panel, the three variables for that
specific case must be specified again. According to them, SCT_MC will calculate and apply the
new mechanical properties deduced from the new variables.
_
FINAL REPORT SAMPLE IN MS WORD
Project 001
03/03/2012
CONTENTS
GENERAL
PLATES
hand lay up, 8.7 mm thick
plate 5.2 mm thick
Sandwich 30 mm
plywood 24 mm
STIFFENERS
Glass Rectangular 50x150
Omega profile 60x50x140
T profile, 70x7 45x10
Bulwark Stiffener 40x30x40
Solid Wood 50x50x50
Omega 40x40x60
Bulb Bar 60x6
Omega 40x30x40
Flat Bar 200x14
BOTTON
Stern panelbotton
Stern frmbotton
Stern longbotton
SIDE
Stern panelside
Stern frmside
Stern longside
DECKS
Main Deck paneldeck
Main Deck frmdeck
Main Deck longdeck
Fore Castle Deck paneldeck
Fore Castle Deck frmdeck
Fore Castle Deck longdeck
BULWARK
Stern panelbulwark
Stern frmbulwark
SUPERSTRUCTURE
Passage House panelsuperstructure
Passage House frmsuperstructure
Passage House longsuperstructure
Deck House Front panelsuperstructure
Deck House Front frmsuperstructure
4
5
5
6
7
8
9
9
10
11
12
13
14
15
16
17
18
18
19
20
21
21
22
23
24
24
25
26
27
28
29
30
30
31
32
32
33
34
35
36
_
IMPORTANT NOTE
Weights indicated for laminates in tables below are dry fibre weights.
It is necessary to have practical data about how much weights per sqm, a laminate with an X% of fibre.
On average, it can be said that for a laminate with a 40% in mass of fibre they are necessary about 650
gr/m2 of fibre,for every mm in laminate thickness, when using a “mat”, and about 1000 gr/m2 when
using “roving".
_
GENERAL
Builder
Building N.
Type of Hull
Design category
Power or Sail
Length of the Hull
Length of the fully loaded waterline at mLDC
Beam of the hull
Beam of the fully loaded waterline at mLDC
Chine beam
Depth
Draugth at mLDC (TC)
Maximum speed at mLDC
v/SQR(Lwl) Coefficient
Operating mode
Loaded displacement mass of the craft
Deadrise angle at 0,4 LWL forward of its aft end
Water specific gravity
m
m
m
m
m
m
m
knots
kg
º
kg/m3
Mono Hull
A "ocean"
Motor
24
23.56
5.8
5.75
5.5
2.6
1.95
16
3.296
Displacement
68500
25
1025
_
PLATES
hand lay up, 8.7 mm thick
Plate's material
laminated kind of ply
Glass
Mat (WR), Manual lay-up
moulding Type
Open mould simple surface
Evaluation Level (EL) of mechanical properties
mass content of fibre
Total Thickness
Total Weight
MATS & ROVINGS
MAT 450
ROV 800
800RV-450M
1700RV-300M
ROV 800
MAT 450
%
mm
kg/m2
EL-b
40.7
9.217
5.75
_
STIFFENERS
Glass Rectangular 50x150
User defined, rectangular
Type of Stiffener
Stiffener's Material
Glass
Mat lay-up (WR) by hand by contact
laminated kind of ply
Glass content in mass
%
Moulding Type
Evaluation Level (EL) of mechanical properties
Web Depth
Base Width of the Profile
Web Thickness
Flange Thickness
Neutral Axis
Shear Section Area
Minimal value for First Momento of area
Second Moment of area
Weight or the Stiffener
MATS & ROVINGS
MAT 300
MAT 450
MAT 600
800RV-450M (only on crown)
800RV-450M (only on crown)
MAT 600
MAT 300
mm
mm
mm
mm
cm
cm2
cm3
cm4
kg/ml
30
Open mould simple surface
EL-b
150
50
5.254
8.777
7.5
7.88
78.219
586.6425
4.75
_
BOTTON
Stern : panelbotton
Units
%
mm
mm
mm
mm
kN/m2
N/mm/mm
N/mm
m
kg/m2
kg/m2
COEFFICIENTS AND PRESSURES USED IN THE CALCULATIONS
kDC = 1
nCG = 3
kAR = 1
kL = 0.614
PBMD base = 114.621
PBM MIN = 38.946
PBMD = 70.378
k2 = 0.481
k3 = 0.026
kC = 1
kSHC = 0.446
As per ISO 12215-5
hand lay up, 8.7 mm thick
Panel's Composition
Panel's Material
Mass content of glass
Thickness
Deflection
Shorter dimension of plate panel
Longer dimension of plate panel
Design pressure
Flexural Moment along "b" direction
Shear stress at b/2
Distance of mid panel from of aft end of LWL
Minimun dry fibre mass for the lay-up
Panel's weight
Values given by the User
Glass
40.7
9.217
410
705
--948.377
12.869
3.2
3.963
5.75
7.894 (formula 35)
70.378
3.39
_
SIDE
Stern : frmside
Units
Stiffener Type
Stiffener's Material
%
Arrangement of the Stiffener
Crown of a curved stiffener
Unsupported span of stiffener or frame
Stiffeners spacing
Effective extent of plating connected to the stiffener
Design pressure
Bending Moment
Neutral Axis
Shear area, Stiffener + Attached Plate
First moment of area (Wx)
Second moment of area (Ix)
Stiffener's weight + attached `plate
Height of stiffener's midpoint above WL
Distance of mid stiffener from of aft end of LWL
mm
mm
mm
mm
kN/m2
Nm
cm
cm2
cm3
cm4
kg/ml
m
m
COEFFICIENTS AND PRESSURES USED IN THE CALCULATIONS
kDC = 1
nCG = 3
kAR = 0.593
kL = 0.572
kZ = 0.998
PDM base = 22.846
PSM MIN = 21.204
PSMP =0 .0155
kCS = 1
kSA = 7.5
As per ISO 12215-5
Omega 40x40x60
Glass
Open mould simple surface
Stiffener's Mould
Glass content in mass
Values given by the User
30
attached to hull or panel
1000
750
------1.47
24.28
123.592
181.5218
12.769
1
2
215.02
38.817
7.043
57.082
23.6541
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