FREECAD COURSE SERIES

In order to generate tanks we load Part module, and create a box solid. Tanks must be created on top of solid geometry, as the ship instance, so first step is create two bow tanks (one per ship side) solid geometries that we will consider (usually ships have a lot of tanks for fuel, fresh water, salt water, load, etc).

When you press Accept weights will be stored in your ship instance. Note: the annotations will be removed when the tool is closed. Weights position are shown in the 3D view. The Ship workbench provides two different tools to generate each instance. Tanks, where fluid shape changes with the angle, needing center of gravity computation at each position.Fixed weights, that are fully linked to ship movements.In order to can compute GZ curve we need to know ship weights, and their position at each roll angle, so weights will be divided in two categories:

FREECAD COURSE SERIES

In this tutorial we will set weights and tanks for our series 60 ship, in a simulated situation. Area involved by GZ curve from 30 to 40 degrees of roll angle must be at least 0.030 m.Area involved by GZ curve up to 30 degrees of roll angle must be at least 0.055 m.Area involved by GZ curve up to 40 degrees of roll angle must be at least 0.090 m.With 30 degrees roll angle, GZ value must be 0.2 m at least.Maximum GZ value must be placed over 30 degrees of roll angle.GM (metacentric height) is the initial tangent of the GZ curve. IMO (International Maritime Organization) set following criteria: GZ is the static moment generated when the ship takes roll angle, of course, since the GZ arm is positive, the ship has a positive moment, and will try to recover upright position, but when GZ turns on negative numbers ship has not anymore stability, reaching a critical situation. In this tutorial we will work with weights and tanks in order to compute GZ curve, the most important hydrostatic stability parameter. Learn more about the Ship workbench from it's dedicated wiki page: Ship Workbench Introduction Before starting this tutorial, please ensure that you have already performed the first part.

Freecad course