General HydroStatics
Ship Stability Software
Command of the Week
(New or interesting aspects of GHS that you may not know about)

GROUP


The GROUP command can be used to establish a name for a group of tanks where they all contain the same substance. A pair of fuel tanks, port and starboard, could be assigned to a group and thereafter addressed in commands such as LOAD by one name.

For example,

GROUP FO1 = WT11.S, WT12.P
LOAD (FO1) 98%

In a typical Status Report all tanks in a group are represented by one line where the group's combined load and center of gravity are shown.

A report showing the details within a group is produced by the GROUP command simply followed by the group name:

GROUP FO1

Then to show the group's summary in the STATUS report,

STATUS TANKS

GROUP names can also appear in the current tank list:

TANK FO1
LOAD 0.8
STATUS TANKS

To delete a group:

GROUP FO1 OFF
STATUS TANKS

Here is the result of the above commands.



The TANK command and the GROUP command can work together to select tanks from a particular region of the vessel. For example,

TANK * /ENDS: 0, 100f
GROUP FOFWD={PNAME} /CONT:"FUEL OIL"

The result is a group named FOFWD with its members being fuel tanks in the forward end of the ship.

Another feature of Groups is their ability to maintain connections between tanks. For example,

GROUP HOLD1 = HOLD1.C -> DB1.P



Note that HOLD1.C spilled to DB1.P until its level got down to its reference point.

After a group is deleted, the loads revert back to the original load settings.

Another way of connecting tanks in a group is to have one tank receiving from multiple source tanks. For example,

GROUP HOLD1 = HOLD1.C <- WT1.S (.2) WT2.S



Note that 20% of the gain in HOLD1.C (its load increased up to its reference point) was from WT1.S, and the remaining came from WT2.S.

If you are having trouble understanding your GHS manual or HELP article where it has,

GROUP HOLD1 = UPPER1.P <- HOLD1.C (.5), UPPER1.P(.5), LOWER1.P

that's because it's wrong. It should be,

GROUP HOLD1 = UPPER1.S <- HOLD1.C (.5), UPPER1.P (.5), LOWER1.P

What are these connections between tanks good for? Well, that's your problem, not ours.


Questions, comments, or requests?
Contact Creative Systems, Inc.

support@ghsport.com

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

www.ghsport.com

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