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

(Requires GHS version 15.88 or later with Condition Graphics)

Ground points offer a unique and effective way to include ground reactions when performing salvage or complex loading calculations. However, with standard ground points, it is up to the user to determine the depth and penetration of each point to yield an accurate model of the scenario under consideration. As environmental or loading conditions change, the ground points must be manually updated to reflect these influences.

Enter GROUND /FLOOR: a new approach to issuing ground points. GROUND /FLOOR will automatically create ground points at optimum locations on the specified geometry components and will assign realistic depths and penetrations to these points based on the surrounding floor conditions. How does it all work?

GROUND /FLOOR allows the user to define the "seafloor" using one of two methods: a data file that contains real-world bathymetry data of the area around the vessel, or a constant depth. When using the file option, points on the seafloor are specified with a location and a depth sounding, and included in the file. The location of each point may be in standard length units, such as feet or meters and referenced from a seafloor datum, or latitude and longitude coordinates using the degrees-minutes-seconds format, e.g. 48d8'39.03", -122d45'17.0136". When using the constant depth option, the seafloor is oriented parallel to the waterplane at the specified depth and extended to infinity in all directions.

Part of the power of GROUND /FLOOR may be realized when it is used iteratively. If the attitude or condition of a vessel changes, a new call to GROUND /FLOOR will update the ground points to reflect the new condition. Take, for example, the following scenario:

For dramatic effect, the LCG and TCG of the fishing vessel are initally set off-center to induce heel and trim. Using the constant depth option, the floor is then decreased to simulate an outgoing tide. Once the vessel is out of the water, the LCG and TCG are shifted back to zero, and once again the vessel is re-floated.

In this simulation, one may see how the ground points attempt to "follow" the most critical grounding locations on the vessel as the floor decreases. The ground points also reflect the shift in LCG and TCG. As the floor increases, the zero heel condition results in a symmetrical pattern. Here, a larger number of points were issued, but GROUND /FLOOR also includes options to tailor the number of points, and their clearances, as needed.

There are many other applications where GROUND /FLOOR might be useful; the example shown here is only demonstrative of the capabilities that await the creative user.

The run file used to create this example may be downloaded here.

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

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