Ship Construction & Stability Flashcards

The distance measured vertically from the keel to the center of gravity is designated as:

Answer: KG

KG is the vertical distance from the keel (K) to the ship's center of gravity (G), a fundamental value in all stability calculations.

What effect does adding topside weight have on a vessel's stability?

Answer: It raises G, reducing GM and worsening stability

Adding weight above the center of gravity raises G, reducing GM and the righting lever arm, which decreases the vessel's stability.

The term 'camber' in ship construction refers to:

Answer: The transverse curvature of a deck, higher at the centerline

Camber is the transverse arch built into a deck, sloping upward toward the centerline, to promote drainage of water off the deck.

A permeability factor of 0.95 for a cargo hold means:

Answer: 95% of the compartment volume can be occupied by floodwater

Permeability is the fraction of a compartment volume that can flood; 0.95 means 95% of the space is available to floodwater, accounting for structure.

Sheer on a vessel is best described as:

Answer: The longitudinal curvature of the deck in profile, higher at bow and stern

Sheer is the rise of the deck in profile toward the bow and stern relative to amidships, providing freeboard and wave clearance at the ends.

In stability terminology, BM represents:

Answer: The distance from the center of buoyancy to the metacenter

BM is the metacentric radius, the vertical distance from the center of buoyancy (B) to the metacenter (M), calculated as I/V.

Which condition describes a vessel with a 'stiff' stability characteristic?

Answer: High GM producing a short, snappy roll period

A stiff vessel has a large positive GM, resulting in strong righting forces and a short, rapid roll period that can be uncomfortable and strain cargo.