MTC Hull & Structural Systems Flashcards

What is the purpose of 'osmotic barrier coating' applied to a fiberglass hull below the waterline?

Answer: To prevent water penetration that causes blistering

Osmotic barrier coatings (typically epoxy-based) seal the fiberglass laminate against water absorption, preventing the hydrolysis that leads to hull blistering.

A marine technician notices soft spots in a fiberglass deck. What is the MOST likely cause?

Answer: Water-saturated core material (balsa or foam)

Soft spots in cored fiberglass decks are almost always caused by water intrusion into the core material, which weakens it structurally and must be replaced.

What is the recommended procedure for sealing a deck hardware fitting to prevent water intrusion?

Answer: Apply marine-grade sealant (polysulfide or polyurethane) under the fitting base

Marine-grade sealants such as polysulfide or polyurethane create a flexible, waterproof bond between hardware and the deck surface, preventing water from entering the deck core.

Which of the following best describes 'freeboard' on a marine vessel?

Answer: The vertical distance from the waterline to the top of the hull at the side

Freeboard is the distance from the waterline to the upper deck edge, and greater freeboard generally means more reserve buoyancy and better seakeeping in rough conditions.

When inspecting a vessel for compliance with US Coast Guard standards, what does 'maximum persons capacity' refer to?

Answer: The maximum number of people the vessel can safely carry based on weight and stability limits

Maximum persons capacity is calculated based on the vessel's length and beam, representing the safe limit of occupants to maintain adequate stability and freeboard.

What is the function of limber holes in a boat's structural frames?

Answer: To allow bilge water to flow freely to the lowest point for pumping

Limber holes are cutouts at the bottom of frames and floors that allow water to flow freely to the bilge sump where it can be pumped out.