AME 5 Q1 – SVE Study

AME 5 Q1

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What is the traditional method for the layup of a Glass Reinforced Plastic (GRP) hull?

A) Applying a single layer of glass fiber and resin using a vacuum bagging technique to ensure even distribution.

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.

D) Inserting pre-formed glass fiber and resin sheets into a mold and heating them to set the shape.

C) Spraying a mixture of glass fiber and resin onto the mold using a high-pressure spray gun for a quick and even application.

Correct Answer: 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.

Explanation: The traditional method for laying up a GRP hull involves placing multiple layers of glass fiber mat (or cloth) into a mold, applying resin to each layer, and then hand-rolling the layers to ensure good resin penetration and remove air bubbles. This process builds up the hull's strength and structural integrity. After the layers are applied, the hull is cured, usually at room temperature or with heat to set the resin.

Incorrect Options:

A) Applying a single layer of glass fiber and resin using a vacuum bagging technique to ensure even distribution.

Explanation: While vacuum bagging is a technique used in advanced composites to remove air and ensure even resin distribution, it is not the traditional method for GRP hull construction. Traditional GRP layup generally involves hand-laying multiple layers and rolling them out, rather than using vacuum bagging.

C) Spraying a mixture of glass fiber and resin onto the mold using a high-pressure spray gun for a quick and even application.

Explanation: This describes the chopper gun method, which is not the traditional hand layup method. The chopper gun is a more modern technique used for faster application but is different from the traditional hand-layup process that involves layering and hand-rolling.

D) Inserting pre-formed glass fiber and resin sheets into a mold and heating them to set the shape.

Explanation: This describes a process similar to pre-preg layup methods or sheet molding compound (SMC), which is not traditional for GRP hulls. Traditional GRP hulls involve applying multiple layers of glass fiber and resin separately and curing them in the mold rather than using pre-formed sheets.

Correct Answer: 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.

Explanation: The traditional method for laying up a GRP hull involves placing multiple layers of glass fiber mat (or cloth) into a mold, applying resin to each layer, and then hand-rolling the layers to ensure good resin penetration and remove air bubbles. This process builds up the hull's strength and structural integrity. After the layers are applied, the hull is cured, usually at room temperature or with heat to set the resin.

Incorrect Options:

A) Applying a single layer of glass fiber and resin using a vacuum bagging technique to ensure even distribution.

Explanation: While vacuum bagging is a technique used in advanced composites to remove air and ensure even resin distribution, it is not the traditional method for GRP hull construction. Traditional GRP layup generally involves hand-laying multiple layers and rolling them out, rather than using vacuum bagging.

C) Spraying a mixture of glass fiber and resin onto the mold using a high-pressure spray gun for a quick and even application.

Explanation: This describes the chopper gun method, which is not the traditional hand layup method. The chopper gun is a more modern technique used for faster application but is different from the traditional hand-layup process that involves layering and hand-rolling.

D) Inserting pre-formed glass fiber and resin sheets into a mold and heating them to set the shape.

Explanation: This describes a process similar to pre-preg layup methods or sheet molding compound (SMC), which is not traditional for GRP hulls. Traditional GRP hulls involve applying multiple layers of glass fiber and resin separately and curing them in the mold rather than using pre-formed sheets.

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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.

B) Glass fiber is corrosion-resistant and flexible; resin has low impact resistance and high thermal conductivity.

A) Glass fiber is lightweight and has high tensile strength; resin provides high thermal resistance and rigidity.

C) Glass fiber is strong and rigid, with high impact resistance; resin is heavy and has low tensile strength.

Correct Answer: D) Glass fiber has high tensile strength and flexibility; resin provides good adhesion and low water absorption.

Explanation: Glass fiber is known for its high tensile strength and flexibility, which makes it ideal for reinforcing materials and improving their strength and impact resistance. Resin (often epoxy or polyester) provides excellent adhesion, forming a strong bond with the glass fibers, and has low water absorption, which helps prevent damage from moisture and ensures durability in marine environments.

Incorrect Options:

A) Glass fiber is lightweight and has high tensile strength; resin provides high thermal resistance and rigidity.

Explanation: While glass fiber is indeed lightweight and has high tensile strength, resin is not typically known for high thermal resistance in the context of hull construction. Instead, the resin’s low water absorption and good adhesion are more critical properties for marine applications.

B) Glass fiber is corrosion-resistant and flexible; resin has low impact resistance and high thermal conductivity.

Explanation: Glass fiber is flexible but not inherently corrosion-resistant; rather, its strength and impact resistance are more relevant. Resin typically does not have low impact resistance or high thermal conductivity in hull construction; instead, good adhesion and low water absorption are more important.

C) Glass fiber is strong and rigid, with high impact resistance; resin is heavy and has low tensile strength.

Explanation: Glass fiber is strong and has high tensile strength but is not typically described as rigid or having high impact resistance. Resin used in hull construction is not heavy; it is designed to be lightweight and provide strength when combined with glass fiber, not low tensile strength.

Correct Answer: D) Glass fiber has high tensile strength and flexibility; resin provides good adhesion and low water absorption.

Explanation: Glass fiber is known for its high tensile strength and flexibility, which makes it ideal for reinforcing materials and improving their strength and impact resistance. Resin (often epoxy or polyester) provides excellent adhesion, forming a strong bond with the glass fibers, and has low water absorption, which helps prevent damage from moisture and ensures durability in marine environments.

Incorrect Options:

A) Glass fiber is lightweight and has high tensile strength; resin provides high thermal resistance and rigidity.

Explanation: While glass fiber is indeed lightweight and has high tensile strength, resin is not typically known for high thermal resistance in the context of hull construction. Instead, the resin’s low water absorption and good adhesion are more critical properties for marine applications.

B) Glass fiber is corrosion-resistant and flexible; resin has low impact resistance and high thermal conductivity.

Explanation: Glass fiber is flexible but not inherently corrosion-resistant; rather, its strength and impact resistance are more relevant. Resin typically does not have low impact resistance or high thermal conductivity in hull construction; instead, good adhesion and low water absorption are more important.

C) Glass fiber is strong and rigid, with high impact resistance; resin is heavy and has low tensile strength.

Explanation: Glass fiber is strong and has high tensile strength but is not typically described as rigid or having high impact resistance. Resin used in hull construction is not heavy; it is designed to be lightweight and provide strength when combined with glass fiber, not low tensile strength.

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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.

D) Heavy weight leading to poor fuel efficiency and complex manufacturing process.

A) High susceptibility to impact damage and easy delamination.

B) Inherent buoyancy issues and poor resistance to water ingress.

Correct Answer: C) Potential for UV degradation and difficulty in repairs; higher initial cost compared to traditional materials.

Explanation: GRP hulls have some notable disadvantages:
- UV Degradation: GRP can be prone to degradation from prolonged exposure to ultraviolet (UV) light, which can weaken the material over time.
- Difficulty in Repairs: Repairs to GRP can be challenging and require specialized techniques and materials.
- Higher Initial Cost: The initial cost of GRP can be higher compared to traditional materials like wood or metal, although it may offer long-term savings due to its durability.

Incorrect Options:

A) High susceptibility to impact damage and easy delamination.

Explanation: GRP hulls are designed to be durable and impact-resistant. While they can suffer from impact damage, they are not inherently more susceptible to damage or delamination than other materials. Properly constructed GRP hulls are relatively resilient to these issues.

B) Inherent buoyancy issues and poor resistance to water ingress.

Explanation: GRP hulls are generally buoyant and provide good resistance to water ingress when properly constructed and maintained. They are designed to be watertight and float effectively, which is a primary advantage of using GRP in hull construction.

D) Heavy weight leading to poor fuel efficiency and complex manufacturing process.

Explanation: GRP hulls are actually known for their lightweight properties, which contribute to better fuel efficiency and overall performance. Additionally, the manufacturing process for GRP hulls, while involving several steps, is not necessarily more complex than other methods and is widely used due to its advantages.

Correct Answer: C) Potential for UV degradation and difficulty in repairs; higher initial cost compared to traditional materials.

Explanation: GRP hulls have some notable disadvantages:
- UV Degradation: GRP can be prone to degradation from prolonged exposure to ultraviolet (UV) light, which can weaken the material over time.
- Difficulty in Repairs: Repairs to GRP can be challenging and require specialized techniques and materials.
- Higher Initial Cost: The initial cost of GRP can be higher compared to traditional materials like wood or metal, although it may offer long-term savings due to its durability.

Incorrect Options:

A) High susceptibility to impact damage and easy delamination.

Explanation: GRP hulls are designed to be durable and impact-resistant. While they can suffer from impact damage, they are not inherently more susceptible to damage or delamination than other materials. Properly constructed GRP hulls are relatively resilient to these issues.

B) Inherent buoyancy issues and poor resistance to water ingress.

Explanation: GRP hulls are generally buoyant and provide good resistance to water ingress when properly constructed and maintained. They are designed to be watertight and float effectively, which is a primary advantage of using GRP in hull construction.

D) Heavy weight leading to poor fuel efficiency and complex manufacturing process.

Explanation: GRP hulls are actually known for their lightweight properties, which contribute to better fuel efficiency and overall performance. Additionally, the manufacturing process for GRP hulls, while involving several steps, is not necessarily more complex than other methods and is widely used due to its advantages.

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