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

DB AddLSWt and AddFixWt
(Requires GHS version 17.00 or later)

(Use the command DB Update to get the latest version of the Data Base software.)

DB AddLSWt is the Data-Base version of the WEIGHT and ADD + commands.

DB AddFixWt is the Data-Base version of the ADD command.

For example:

DB AddLSWt /WEIGHT/ 3000, 48F, 0, 4.0

is equivalent to,

WEIGHT 3000, 48F, 0, 4.0

For weights not in the light ship:

DB AddFixWt "Crew and Effects" 4.0 1.0F 0 11.5
DB GetFixWt "Crew and Effects"

is equivalent to,

ADD "Crew and Effects" 4.0 1.0F 0 11.5
DB PutFixWt "Crew and Effects"

But this is only the tip of the iceberg. DB AddLSWt and DB AddFixWt provide extensive templates for entering parameters.

For example,

DB AddFixWt "Store Top"

brings up this template:

Nothing more than the Weight and CG fields are required in addition to the name, but all of the many parameters offered by the ADD command are covered as well.

Everyone wants to know, "What are Segments?" The ADD command can take a series of segments. For example,

ADD "Store Top" 1.0, 22F, 0, 12.0; 1.5, 23F, 0, 12.5

The two segments are two weights with their CG values separated by the semicolon.

Here is what it looks like in the AddFixWt template:

The DISTRIBUTE button brings up options for distributing a weight longitudinally.

A good example for that is the light ship distribution showing here in the AddLSWt template.

All of the distribution options available with the ADD command are represented. But here we see the direct input of the weight-density curve.

Check the "Edit in Table Form" and get this:

Back in the main template, the red "Ref" button gets into setting a reference point.

Once a reference point is established, all of the LTV coordinates are relative to the reference point. You can enter numbers for the reference point coordinates, or you can use the "Pick" buttons to select locations that have been associated with "Reference Words."

Note that zero has been entered at FR25 which caused the Frame 25 location plus zero to be entered for the longitudinal reference.

Reference Words are stored for a "family" of ships. There need be only one ship in a family, but the family mechanism is there so that ships that are nearly the same can share the reference locations.

Define Ref Words brings up the templates for managing the reference word lists.

Longitudinal Reference Words can include frame names and locations if those are defined, as is the case here. Other words can be defined as well.

Now going back to the weight distribution table, note that the longitudinal reference, which can vary.

There is a handy dialog to reset all of the references.

If the distribution happens to be in "blocks" (constant weight density over lengths), a block-oriented version of the table takes blocks of weights directly.

The Display button brings up a display showing the location, size and extent of the weight. Weights do not have shapes; the circle is representative of a sphere proportional to the weight, and the yellow bar shows the actual longitudinal span of distributed weights.

In this main template the sum of the segments is shown. In the segments template the display which the button brings up shows each segment with a cross at the center.

The lower part of the main template is divided into three sections that cover all of the other parameters that are available in the ADD command. Clicking the button reveals the details.

This is a brief survey. Some features are left for you to discover.

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