Procedure 1. Start Modelmaker
Click the Modelmaker icon in the Autoship group/folder. When the view screen appears, pull down the File menu and click New GF. In the dialogue that appears, give your model a file name (MYBARGE.GF1, for example), and then specify a directory to store it in. Make a note of the filename and the directory where you are storing the file. Click OK to close the dialogue and accept your input. 2. Create a Part
On the top menu bar, click Options and select Meters as your measuring unit.
Select the Part Create/Edit command in the Edit menu; a dialogue will appear. Under Part Name you will see NEWPART highlighted. Type HULL over it (it does not matter whether you type in upper or lower case). You must have a part named HULL - if you don't, the model won't work in Autohydro. For Side, select the Center radio button. For Class, select the Displacer radio button. After you have made these selections, click OK. Now you are back at the main screen, which is still blank. Now for the Components:
We will create the model as a combination of two box-shaped components. The first component will be the parallel midship section including the aft rake, and we will shape it to form the aft rake. The second component will be the forward rake, and in order to demonstrate different techniques we will shape it using a different method. We will then join the two components together to make a single component.
3. Create Component 1
Go back to the Edit menu and select the Component Create command. In the dialogue that appears, you will see HULL on the left hand side. If it is not already highlighted, click to highlight it. On the right hand side you will see a list of the basic component shapes, called primitives, that Modelmaker uses as building blocks.
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Click the Box radio button and then click Input; the Create Box dialogue will appear. Under Component Name you will see C1.
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Click the FWD End input box and type 15f (the system will add three significant figures - 15.000f).
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Click the AFT End input box and type 20a.
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Click the Station Spacing input box and type 2.5 to specify the space between adjacent stations. Later, if you find this station spacing too large for fitting parts and components together smoothly, you can change the spacing by adding more stations with the Fill command in the Edit menu.
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To the right of OUTBOARD, in the TRANS input box, type 5 to set the halfbreadth.
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To the right of TOP, in the VERT input box, type 5 to set the height of the deck above baseline.
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In the Side Factor box click Center.
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Click OK.
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In the Create Component dialogue, click Done to return to the main screen. A rectangle will now appear on the screen.
Choose Iso (Isometric) from the View menu. This will display the first component of the model showing all the stations, with the currently selected station (the forward-most one) highlighted in black and the red cross-shaped cursor highlighting the first vertex of the station.
4. Shape Component 1
At this point, it is time to shape the first component: •
Shift through the group of stations to the aft-most station, by pressing F6 until the aft-most station is highlighted. Location, near the bottom left of the screen, will read 20a.
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The cursor will appear at the bottom-center of the station, highlighting the first vertex of the station. We will change the shape of this section by moving the two bottom vertices up to form the lower edge of the headlog. To do this, press the up arrow on the keyboard (repeatedly) until you can see 4.5 in the first vertical cell under Edit Points (at the left of the screen).
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Shift the cursor to the next vertex on the station by pressing F4.
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Move the cursor up with the up arrow until the 2nd vertical cell under Edit Points reads 4.5. Press Enter to update the changes and redraw the view.
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Shift to the next station forward by pressing F5.
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Shape this station differently (just for practice): type 2.25 in the first vertical cell and 2.25 in the second vertical cell, then press Enter to update the changes and redraw the view.
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If at any time the screen does not show changes that you have made, click the Redraw button.
Now we will create the second component. 5. Create Shaped Component 2
Select the Component Create command in the Edit menu; then, in the Create Component dialogue: click HULL, then click Box, and then click Input. The Create Box dialogue will now appear, and in it you will see C2 as the name of this component. Now type these values:
FWD End 20f AFT End 15f Station Spacing 2.5 Outboard Trans 5 Top Vert 5 Click the SLOPING? checkbox for Bottom. This will open up three additional input boxes. Input the following values:
Vert 4.5 Long 20f Vert 0 Long 15f Make sure that Side Factor is set to Center, then click OK. Click Done. If the main screen shows no change, select the View Part command from the View menu - you should now see the entire part.
To scroll through the components of the model, use the space bar.
6. Join Components
We will now join the two components for a cleaner appearance. Note that whether a part is made of one component or several, there will be no difference in the resultant calculations.
Select the View Profile command from the View menu to see the entire model in profile.
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From the Edit menu, select the Join To command; the Join dialogue will appear. Under Join Component, select HULL for part and C2 for component.
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Under Component To Join To, select HULL for part and C1 for component.
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Click the External button.
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Click OK.
You will now see your complete model without any break between components.
Note that all reference to the component C2 is gone - it has been amalgamated with component C1. 7. Save the File
Select the Save command from the File menu.
8. Start Autohydro and Find Lightship Drafts
Start Autohydro by clicking the Autohydro icon in the Autoship group/folder. When Autohydro has finished starting, select the Open command from the File menu. Next, select the GF you just created and click OK. After the GF is loaded, you should see a representation of your barge in the main views.
Now we are ready to input a draft and perform calculations.
Suppose the empty drafts are:
1.34m aft (at the forward end of the aft rake, at 15a); and 1.26m fwd (at the aft the of the forward rake, at 15f) Input these drafts into Autohydro by typing in the command line: DRAFT 1.34 @ 15a, 1.26 @ 15f (Enter)
Note that the comma is optional, and it does not matter whether you type in upper case or lower case.
Now let's get Autohydro to find the displacement and longitudinal center of gravity (LCG) corresponding to these drafts. In the command line, type:
SOLVE WEIGHT LCG (Enter)
In the Hydrostatic Values window you should now see the following results:
Draft status: Aft = 1.35 Mid = 1.30 Fwd = 1.25 m Lightship: 419.0 MT Fixed Weight LCG: .194a
Note that the drafts shown are not the drafts you put in. This is because the drafts shown are being measured at the extreme ends of the vessel, while the drafts you input were located closer to midships. Reset the locations where the drafts are reported so they match your draft mark locations, by typing in the command line:
DRAFT "US KEEL" 0 @ 15a, 0 @ 15f (Enter)
Now we know the lightship weight and its LCG. By default, both the transverse and vertical center of gravity are zero. Assuming we had calculated the vertical center of gravity to be 3.2m above baseline, we can input this value with the command:
VCG 3.2 (Enter)
Since you have changed some variables, the vessel is no longer in equilibrium. This will be indicated by the red Solve button in the top left of the screen.
Equilibrium in Autohydro
Autohydro considers the vessel to be in equilibrium when three conditions are met:
1. the displacement = the total of all weights (lightship + added weights + tank loads) 2. the LCB = trimmed LCG (RAt = 0) 3. the TCB = heeled TCG (RAl = 0)
To get Autohydro to calculate a new equilibrium, click the Solve button. After a quick calculation, the Solve button will turn grey, the graphics window showing the model will be updated, and the Hydrostatics Values window will show new values. At this point, Autohydro has a model to work with, has a reference line for measuring the drafts, and knows the vessel's lightship weight and center of gravity.
Now we can add some deck cargo and find the drafts that result.
9. Add Deck Cargo and Find Resultant Drafts
Autohydro maintains two separate weight categories: Fixed and Tank Loads. The Fixed category has two further sub-categories:
1. Fixed Weight:
a. Lightship Weight - can be set with the WEIGHT command, or by specifying drafts or depth and using the SOLVE WEIGHT command. b. Added Weights - can be input with the ADD command, or in a dialogue accessed via the Fixed Weight button.
2. Tank Loads •
Tank Loads can be specified with the LOAD command, or in a dialogue accessed from the Tank Loads button.
In our barge model we will add two fixed weight items as deck cargo. (If we had defined some tanks in the model, we could also have loaded them with contents.) To add a fixed weight item, click the Fixed Weight button.
In the Weight List dialogue that appears, click Add, change the label New Weight Item#01 to Lumber on deck, set its LCG to 12a, VCG to 6.5, and Weight to 3.
To add the second fixed weight item, click Add, change New Weight Item#01 to Forklift on deck, set its LCG to 10f, VCG to 6.1, and Weight to 1.3.
Close the dialogue box by clicking OK and return to the main Autohydro screen.
Even though you have now changed some variables, when you exit the Added Weights dialog, Autohydro will automatically find the new equilibrium. Now we know the total weight and center of gravity of the vessel and cargo, and the resultant drafts. All we need to do now is to create a report of this condition and print it out.
10. Generate and Print Report
Autohydro has different commands to produce different outputs. The most commonly used (and most general) is Status, which creates an overall status report of the current loading condition.
To generate a report: type STATUS in the command line, then click Enter. This will fill the output window with lines of unformatted information. To see the formatted report, click the Report button.
You can resize the Report window (like all other windows in Autohydro), and use its scroll bars to adjust your view of the page. Since the Report window is an editable spreadsheet, you can both edit directly within Autohydro and edit a file that has been opened by Excel or Word.
To print the report, choose Print from the File menu.
Review You have used Modelmaker to create and edit a vessel model. You have used Autohydro to calculate some hydrostatic behaviour of the model. You have produced a report of the vessel condition.
Task A
Add tanks to the barge created in the Quick Lesson We will create 6 tanks in all: Two void tanks, a Forepeak and an Aftpeak, plus four cargo tanks in between. Two of the cargo tanks will have a recess on top.
A1
Load MYBARGE.GF1
(The name you used for your geometry file may be different)
Click View - ISO to get the best viewing angle.
A2
Add more stations to the model so that Modelmaker can fit parts together smoothly: •
From the Edit menu choose Fill
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In the Fill station dialog, in the Maximum Station Spacing field, type .5, and click OK.
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This will fill the HULL with more stations and ensure smooth fits.
A3 Create the fwd tank: Part: (Edit - Part Create/Edit and then Add)
Part name: FOREPEAK Side: Center Class: Container Category : Misc. Contents: SEA WATER Component: (Edit - Component Create, select FOREPEAK, Box, Input) FWD: 21f AFT: 14.5f Station spacing: Match Stations to Hull Outboard Trans: 6 Top Vert: 6 Bottom Vert: -1 Note that the dimensions extend beyond the hull. To get Modelmaker to fit, or trim, parts properly, you must specify slightly larger dimensions for the part that is to be fitted to another part. A4 Fit FOREPEAK to HULL: From the Edit menu choose Fit to. In the Fit Component dialog, under Fit Component, for Part Name choose FOREPEAK and the appropriate component.
Under Part or Component to Fit To, for Part Name choose HULL and the appropriate component.
Under Type of Fit choose Internal.
Click OK.
A5
Create the aft tank: Part: Part name: AFTPEAK Side: Center Class: Container Category: Misc. Contents: Seawater Component: (Box) FWD: 14.5a AFT: 21a Station spacing: Match Stations to Hull Outboard Trans: 6 Top Vert: 6 Bottom Vert: -1
A6
Fit AFTPEAK to HULL as in step 1.3.
A7
Create a port tank aft of midships, out of 3 components:
Part: Part name: NO1
Side: Port Class: Container Category: DO Contents: Diesel oil Component: (Box) FWD: 5a AFT: 14.5a Station spacing: Match Stations to Hull Outboard Trans: 6 Top Vert: 6 Bottom Vert: -1 Component, for the second of the 3 components: (Box) FWD: 0 AFT: 5a Station spacing: Match Stations to Hull Inboard Trans: 2 Outboard Trans: 6 Top Vert: 6 Bottom Vert: -1 Component, for the third of the 3 components: (Box) FWD: 0 AFT: 5a Station spacing: Match Stations to Hull Outboard Trans: 3 Top Vert: 3 Bottom Vert: -1 Join the third component to the second component: Click Edit - Join To.
Under Join Component, for Part Name pick NO1.P, for Comp Name pick C3. Under Component to Join to, for Part Name pick NO1.P, for Comp Name pick C2. Click External and then OK.
Join the second component to the first component in the same manner.
Now you have a tank with a recess in the top.
A8
Fit NO1.P to HULL, choosing INTERNAL.
A9
Create a starboard tank aft of midships, matching the NO1.P tank. We will create this tank in a different way. We will start by creating a regular cubic shape. Next, we will create a temporary smaller cubic shape. Then we will fit the larger one to the smaller one. Finally, we will delete the temporary part.
Part: (the tank part) Part name: NO1 Side: Starboard Class: Container Category: DO Contents: Diesel oil Component: (Box) FWD: 0
AFT: 14.5a Station spacing: Match Stations to Hull Outboard Trans: 6 Top Vert: 6 Bottom Vert: -1 Part: (the temporary part) Part name: Temp Side: Starboard Component: (Box) FWD: 0 AFT: 5a Station spacing: Match Stations to Hull Inboard Trans: -1 Outboard Trans: 2 Top Vert: 7 Bottom Vert: 3
A10
Fit NO1.S against the part called Temp, choosing EXTERNAL.
A11
Fit NO1.S to HULL, choosing INTERNAL.
A12
Delete the temporary Part:
Go to Edit - Delete Part/Component, pick TEMP.S and click on the Delete Part/Comps button. Click on Yes' at the message "Delete part TEMP.S" and then click on Close.
Now you have a starboard tank exactly opposite to the port side tank created previously.
A13
Create a port tank fwd of midships: Part: Part name: NO2 Side: Port Class: Container Category: Misc. Contents: Gasoline Component: (Box) FWD: 14.5f AFT: 0 Station spacing: Match Stations to Hull Outboard Trans: 6 Top Vert: 6 Bottom Vert: -1
A14
Fit NO2.P to HULL internally.
A15
In the Edit menu, click on Opposite part.
In the Opposite Part dialog choose NO2.P.
The second field will show NO2.S. Click OK. Now your barge is fitted with all six tanks.
Task B
Create sounding tubes for the cargo tanks B1
In the edit menu, click Sounding Tube.
B2
In the Sounding Tube dialog, choose the part to have the sounding tube; start with NO1.P.
B3
Click Insert Points, and then click it again.
B4
In the grid, type in the following values for points 1 and 2 (Note that Point 1 must be the lowest point on the tube, and be sure to click on Record to register the changes):
Pt. 1
Long
Trans
Vert
0.2a
4.8p
.005
Pt. 1
0.2a
4.8p
B5
Create sounding tubes for the other tanks in the same way. Remember to designate aft or forward, and port or starboard.
5.25
Task C
Create a deckhouse
C1
Create a deckhouse with the following dimensions: length: 5m - fwd end at 14a, aft end at 19a height: from the deck to 2.5m above deck, width: 3m wide - inboard at 2.5m from centerline, the outboard side overhangs the starboard side of the hull by .5m.
Part: Part name: Deckhouse Side: Starboard Class: Sail Component: (Box) FWD: 14a AFT: 19a Station spacing: Match Stations to Hull Inboard Trans: 2.5 Outboard Trans: 5.5 Top Vert: 7.5 Bottom Vert: 5 The modifications to the model are now finished. Save your model. To avoid overwriting your original model, use a different name; we suggest incrementing the extension, i.e., if you named the original barge MYBARGE.GF1, name this model MYBARGE.GF2.
