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

ADD DELTA


How would you go about finding where to locate deck cargo so as not to affect trim? Every naval architect knows that's what the center of flotation is good for.

Take the problem of finding the weight of the cargo that would immerse the ship to a given draft while keeping the same trim: You would set the target draft, observe the new hydrostatics, and issue an ADD command for whatever the difference is between the new displacement and the existing vessel weight, locating it at the CF.

No need to copy numbers; do it in one run. For example, given this initial condition with the desired draft set to 4.120:


The setup for the ADD command would be,

VARIABLE W
SET W={DISPL} MINUS {WEIGHT}
ADD "CENTER CARGO HERE" {W}, {LCF}, {TCF}, 6.0
SOLVE


The result is not perfect because the trim changed slightly and the draft is not quite on target. This is primarily due to the fact that the CF changed.

A quicker and easier way to hit the target is to use ADD DELTA. For example,

ADD "CENTER CARGO HERE" DELTA, ?, ?, 6.0



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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