Which of the following best explains the process of osmosis in glass reinforced plastic (GRP) hulls and the formation of osmotic blisters in service?
B. Osmosis occurs when water molecules pass through the GRP laminate, entering voids and reacting with soluble materials within the laminate. This results in the build-up of pressure, causing the GRP layers to separate and form blisters.
Which of the following are three possible causes of delamination in glass reinforced plastic (GRP) hulls?
A. Excessive moisture ingress, poor adhesion between laminate layers, and impact damage.
Which of the following are three causes of delamination in glass reinforced plastic (GRP) hulls?
A. Excessive moisture ingress, poor resin curing, and impact damage.
What are some disadvantages of GRP (Glass Reinforced Plastic) hulls in service?
C) Potential for UV degradation and difficulty in repairs; higher initial cost compared to traditional materials.
What are the advantages of resin infusion molding compared to traditional methods of construction?
B) Improved fiber-to-resin ratio, reduced air voids, better control over material properties, and enhanced structural integrity.
Which of the following best describes the full process for the treatment of a glass reinforced plastic (GRP) hull suffering from the effects of osmosis?
B. Remove any visible blisters by cutting them out, thoroughly clean and dry the exposed area, fill the void with a marine-grade filler, sand the surface smooth, apply a primer, and then repaint the hull to ensure protection.
What is the traditional method for the layup of a Glass Reinforced Plastic (GRP) hull?
B) Laying down multiple layers of glass fiber mat and resin in a mold, followed by a curing process, with each layer being hand-rolled to remove air bubbles.
When treating a single osmotic blister on a glass reinforced plastic (GRP) hull, which of the following procedures is most appropriate?
C. Cut away the blistered area entirely, clean and dry the exposed surface, fill the void with a marine-grade filler, and then sand, prime, and repaint the area.
Which of the following are two effective methods for repairing delamination in a sandwich construction glass reinforced plastic (GRP) hull?
C. Cut out the delaminated section, fill the cavity with a core material, and then cover with a new layer of laminate.
Which part of the underwater section of a glass reinforced plastic (GRP) hull is most commonly affected by osmotic blisters?
A. The keel and the areas around the bilge.
Which of the following are three design problems that can lead to stress cracking in glass reinforced plastic (GRP) hulls?
A. Sharp corners or edges in the hull design, excessive weight concentration in specific areas, and insufficient reinforcement in high-stress zones.
Which of the following are two effective methods for detecting delamination in glass reinforced plastic (GRP) hulls during service?
A. Tapping the hull with a metal hammer to listen for changes in sound and using a moisture meter to measure the moisture content.
Why is simply drying out a glass reinforced plastic (GRP) hull not a sufficient cure for the effects of osmosis?
A. Drying out the hull removes all moisture, but it leaves behind the weakened laminate and does not repair any structural damage caused by osmosis.
Which of the following are three causes of stress cracking in glass reinforced plastic (GRP) hulls?
A. Sharp corners or edges in the hull design, excessive weight concentration in specific areas, and insufficient reinforcement in high-stress zones.
What is the term "root whitening" in glass reinforced plastic (GRP) hull construction, and where is it most likely to occur?
A. Root whitening refers to a discoloration or fading of the gelcoat layer, most commonly occurring around the waterline and hull sections exposed to high UV radiation.
Which of the following are two possible actions to take if root whitening is discovered in a glass reinforced plastic (GRP) hull?
A. Reapply a new gelcoat layer and perform a thorough inspection to ensure UV protection.
How does resin infusion molding help virtually eliminate the onset of osmosis in a GRP hull?
B) By creating a continuous, void-free barrier with improved fiber-to-resin ratio that reduces water absorption.
Which properties of glass fiber and resin make them suitable for the construction of a hull?
D) Glass fiber has high tensile strength and flexibility; resin provides good adhesion and low water absorption.
What is the process of resin infusion molding for the production of a Glass Reinforced Plastic (GRP) hull?
B) Placing dry glass fiber fabric in a mold, sealing the mold, and then injecting resin under vacuum pressure to infuse the fabric and cure the composite.
Which of the following are three causes of osmotic blisters in glass reinforced plastic (GRP) hulls?
A. Inadequate gelcoat thickness, high moisture content in the hull, and poor bonding between laminate layers.
Which of the following methods is most effective for detecting osmosis in a glass reinforced plastic (GRP) hull during service?
C. Measuring the moisture content of the hull using a moisture meter and looking for raised, soft, or discolored areas that may indicate osmotic blistering.
Which of the following are two possible reasons for root whitening in glass reinforced plastic (GRP) hull construction?
A. Prolonged exposure to ultraviolet (UV) light and degradation of the gelcoat layer due to environmental conditions.
