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General HydroStatics
Ship Stability Software |
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Command of the Week
(New or interesting aspects of GHS that you may not know about) |
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Rig @Rig
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Last week's COW demonstrated how the shapes produced by the @RIG method in
DB EditLSwt can also become additions to the geometry for calculating wind moments.
Then we wondered if the @Rig method might apply to another kind of rig. We used it to make a simple model. Here is the rendering out of DB EditLSwt for the weights: |
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| The EditLSwt main dialog shows the weight items that were generated: |
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| The corresponding geometry for displacement and wind-moment calculations (shown in the zero-ballast condition): |
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For calculating weights, the columns are hollow cylinders.
The buoyant envelope was generated by
reproducing the parameters except the wall thickness was
removed and the density was set to zero. (If the name of an
element ends in a minus sign, it will not appear in a rendered
view while checking the weight model.)
Here we were importing the columns (The "Do - only" button makes it easy): |
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They come together to produce stability graphs. Here the wind speed was
set at 90 knots.
This first one is at zero ballast: |
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| This is the ballasted draft: |
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| Stability at zero and 45-degree axis: |
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| This is the run file that was used: |
PROJECT RIGRIG
ENTER PMX /DIRECT
MACRO MakeHull
CREATE HULL
ENDS -100,100
top 20
bot 0
out 84
in 36
RADIUS (1) 5
RADIUS (2) 5
RADIUS (3) 5
RADIUS (4) 5
//
DISPLAY
MACRO MakeTank
CREATE BAL%%91S
ENDS %%92,%%93
INB 20
FIT HULL
///
CREATE BAL%%91P
OPP BAL%%91S
///
//
.MakeTank 1,-100,-80
.MakeTank 2,-80,-40
.MakeTank 3,-40,0
.MakeTank 4,0,40
.MakeTank 5,40,80
.MakeTank 6,80,100
WRITE RIGRIG.GF
/
IF NDISPLACERS=0 THEN
.MakeHull
END
QUIT PM
DB EDITLSWT
COPY "http://www.ghsport.com/cows/349/dbwimp.txt", "dbwimp.rf"
MACRO GetParts
RUN "dbwimp.rf" /call
VARIABLE (STR) YN
INPUT "Import more (Y or N)? " YN
IF "{YN}"="Y" THEN EXIT GetParts
/
.GetParts
DELETE ALL WEIGHTS+
WEIGHT 0
LOAD (*) 0
DB GetLSWt "/WEIGHT/HULLS"
DB GetLsWt
SOLVE
RENDER
REPORT
STATUS WEIGHT:ALL, LI(HULLS), DISPL, WPL
WIND 90
HMMT WIND /BAND
RA 0,2, ...,36
LOAD (*) 1.0
LOAD (BAL1*,BAL6*) 0.5
HMMT OFF
HEEL 0
SOLVE TRIM
RENDER
STATUS WEIGHT:ALL, LI(HULLS), DISPL, WPL
HMMT WIND /BAND
RA 0,2, ...,36
AXIS 45
HMMT WIND /BAND
RA 0,2, ...,36
PRINT PREVIEW
REPORT OFF
AXIS 0
erase "dbwimp.rf" /nor
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Questions, comments, or requests?
Contact Creative Systems, Inc. USA phone: 360-385-6212 Fax: 360-385-6213 Office hours: 7:00 am - 4:00 pm Pacific Time, Monday - Friday Mailing address: PO Box 1910 Port Townsend, WA 98368 USA Click here for an index to this and previous COWs |