AME 5 Q6

1 / 4

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.

C. Inadequate anti-fouling maintenance, frequent washing with abrasive cleaners, and poor ventilation.

D. Low-quality resin, improper curing of the laminate, and excessive use of sealants.

B. High moisture content in the laminate, inadequate gelcoat thickness, and poor adhesion between laminate layers.

Correct Answer:

A. Sharp corners or edges in the hull design, excessive weight concentration in specific areas, and insufficient reinforcement in high-stress zones.

Explanation:
1. Sharp corners or edges in the hull design: Sharp corners or edges create localized stress concentrations. These points are prone to cracking because the stress is not distributed evenly, leading to stress fractures in those areas.
2. Excessive weight concentration in specific areas: Concentrating weight in particular areas of the hull can cause localized stress. The hull may not be designed to handle such concentrated loads, resulting in stress cracking in those areas.
3. Insufficient reinforcement in high-stress zones: High-stress areas, such as around fittings or joints, require additional reinforcement. Without adequate reinforcement, these areas are more likely to experience stress cracking due to insufficient structural support.

Incorrect Answers:

B. High moisture content in the laminate, inadequate gelcoat thickness, and poor adhesion between laminate layers.

Why it's incorrect:
1. High moisture content in the laminate: While moisture issues can lead to delamination and osmotic blisters, they are not typically the primary cause of stress cracking. Stress cracking is more related to design and structural issues rather than moisture alone.
2. Inadequate gelcoat thickness: This primarily affects the protection and appearance of the surface but does not directly cause internal stress cracking.
3. Poor adhesion between laminate layers: This can lead to delamination and other internal issues but is not specifically a cause of stress cracking, which is more about structural design and load distribution.

C. Inadequate anti-fouling maintenance, frequent washing with abrasive cleaners, and poor ventilation.

Why it's incorrect:
1. Inadequate anti-fouling maintenance: This affects the protection against marine growth but does not directly cause stress cracking in the laminate.
2. Frequent washing with abrasive cleaners: This can damage the surface finish but does not typically cause internal stress cracking.
3. Poor ventilation: While poor ventilation can lead to moisture problems, it is not directly related to stress cracking, which is more about structural and design factors.

D. Low-quality resin, improper curing of the laminate, and excessive use of sealants.

Why it's incorrect:
1. Low-quality resin: This affects overall laminate strength and durability but is more related to general failure rather than specific stress cracking.
2. Improper curing of the laminate: This affects the bonding and strength of the laminate but does not directly lead to stress cracking unless it results in significant structural issues.
3. Excessive use of sealants: Sealants impact joint sealing and surface protection but do not directly cause stress cracking, which is related to structural design and load distribution.

Correct Answer:

A. Sharp corners or edges in the hull design, excessive weight concentration in specific areas, and insufficient reinforcement in high-stress zones.

Explanation:
1. Sharp corners or edges in the hull design: Sharp corners or edges create localized stress concentrations. These points are prone to cracking because the stress is not distributed evenly, leading to stress fractures in those areas.
2. Excessive weight concentration in specific areas: Concentrating weight in particular areas of the hull can cause localized stress. The hull may not be designed to handle such concentrated loads, resulting in stress cracking in those areas.
3. Insufficient reinforcement in high-stress zones: High-stress areas, such as around fittings or joints, require additional reinforcement. Without adequate reinforcement, these areas are more likely to experience stress cracking due to insufficient structural support.

Incorrect Answers:

B. High moisture content in the laminate, inadequate gelcoat thickness, and poor adhesion between laminate layers.

Why it's incorrect:
1. High moisture content in the laminate: While moisture issues can lead to delamination and osmotic blisters, they are not typically the primary cause of stress cracking. Stress cracking is more related to design and structural issues rather than moisture alone.
2. Inadequate gelcoat thickness: This primarily affects the protection and appearance of the surface but does not directly cause internal stress cracking.
3. Poor adhesion between laminate layers: This can lead to delamination and other internal issues but is not specifically a cause of stress cracking, which is more about structural design and load distribution.

C. Inadequate anti-fouling maintenance, frequent washing with abrasive cleaners, and poor ventilation.

Why it's incorrect:
1. Inadequate anti-fouling maintenance: This affects the protection against marine growth but does not directly cause stress cracking in the laminate.
2. Frequent washing with abrasive cleaners: This can damage the surface finish but does not typically cause internal stress cracking.
3. Poor ventilation: While poor ventilation can lead to moisture problems, it is not directly related to stress cracking, which is more about structural and design factors.

D. Low-quality resin, improper curing of the laminate, and excessive use of sealants.

Why it's incorrect:
1. Low-quality resin: This affects overall laminate strength and durability but is more related to general failure rather than specific stress cracking.
2. Improper curing of the laminate: This affects the bonding and strength of the laminate but does not directly lead to stress cracking unless it results in significant structural issues.
3. Excessive use of sealants: Sealants impact joint sealing and surface protection but do not directly cause stress cracking, which is related to structural design and load distribution.

2 / 4

Which of the following are three causes of delamination in glass reinforced plastic (GRP) hulls?

B. Inadequate paint application, high ambient temperatures during construction, and poor surface cleaning.

D. Frequent washing with abrasive cleaners, poor anti-fouling maintenance, and inadequate hull ventilation.

A. Excessive moisture ingress, poor resin curing, and impact damage.

C. Incorrect hull shape design, improper adhesive use, and excessive use of sealants.

Correct Answer:

A. Excessive moisture ingress, poor resin curing, and impact damage.

Explanation:
1. Excessive moisture ingress: Moisture can penetrate the GRP laminate and cause osmotic blistering, which can lead to delamination. The trapped moisture creates pressure and weakens the bond between the laminate layers.
2. Poor resin curing: Inadequate curing of the resin can result in weak bonding between the laminate layers. This poor bond can lead to delamination, as the layers may separate under stress or pressure.
3. Impact damage: Physical impacts can cause cracks or damage to the GRP laminate, compromising the integrity of the bond between layers. This damage can lead to delamination over time.

Incorrect Answers:

B. Inadequate paint application, high ambient temperatures during construction, and poor surface cleaning.

Why it's incorrect:
1. Inadequate paint application: Poor paint application affects the outer surface and protection of the GRP but does not directly cause internal delamination.
2. High ambient temperatures during construction: While high temperatures can affect the curing process, they are not direct causes of delamination. Problems with delamination are usually related to internal issues rather than external temperature effects.
3. Poor surface cleaning: This impacts surface appearance and adhesion of coatings but does not typically cause internal delamination.

C. Incorrect hull shape design, improper adhesive use, and excessive use of sealants.

Why it's incorrect:
1. Incorrect hull shape design: While poor design can lead to other issues, delamination is more directly related to moisture, curing, and impact rather than shape alone.
2. Improper adhesive use: Adhesive issues can affect bonding but are not the primary cause of delamination in the laminate layers. Delamination is more related to the laminate itself rather than adhesives used in construction.
3. Excessive use of sealants: Excessive sealants can cause issues with joints but do not directly lead to delamination of the laminate layers.

D. Frequent washing with abrasive cleaners, poor anti-fouling maintenance, and inadequate hull ventilation.

Why it's incorrect:
1. Frequent washing with abrasive cleaners: This primarily affects the surface finish and does not typically cause internal delamination of the laminate.
2. Poor anti-fouling maintenance: This impacts the protection of the hull against marine growth but does not directly cause delamination.
3. Inadequate hull ventilation: Poor ventilation can lead to moisture issues and mold but is less directly related to delamination compared to moisture ingress and poor resin curing.

Correct Answer:

A. Excessive moisture ingress, poor resin curing, and impact damage.

Explanation:
1. Excessive moisture ingress: Moisture can penetrate the GRP laminate and cause osmotic blistering, which can lead to delamination. The trapped moisture creates pressure and weakens the bond between the laminate layers.
2. Poor resin curing: Inadequate curing of the resin can result in weak bonding between the laminate layers. This poor bond can lead to delamination, as the layers may separate under stress or pressure.
3. Impact damage: Physical impacts can cause cracks or damage to the GRP laminate, compromising the integrity of the bond between layers. This damage can lead to delamination over time.

Incorrect Answers:

B. Inadequate paint application, high ambient temperatures during construction, and poor surface cleaning.

Why it's incorrect:
1. Inadequate paint application: Poor paint application affects the outer surface and protection of the GRP but does not directly cause internal delamination.
2. High ambient temperatures during construction: While high temperatures can affect the curing process, they are not direct causes of delamination. Problems with delamination are usually related to internal issues rather than external temperature effects.
3. Poor surface cleaning: This impacts surface appearance and adhesion of coatings but does not typically cause internal delamination.

C. Incorrect hull shape design, improper adhesive use, and excessive use of sealants.

Why it's incorrect:
1. Incorrect hull shape design: While poor design can lead to other issues, delamination is more directly related to moisture, curing, and impact rather than shape alone.
2. Improper adhesive use: Adhesive issues can affect bonding but are not the primary cause of delamination in the laminate layers. Delamination is more related to the laminate itself rather than adhesives used in construction.
3. Excessive use of sealants: Excessive sealants can cause issues with joints but do not directly lead to delamination of the laminate layers.

D. Frequent washing with abrasive cleaners, poor anti-fouling maintenance, and inadequate hull ventilation.

Why it's incorrect:
1. Frequent washing with abrasive cleaners: This primarily affects the surface finish and does not typically cause internal delamination of the laminate.
2. Poor anti-fouling maintenance: This impacts the protection of the hull against marine growth but does not directly cause delamination.
3. Inadequate hull ventilation: Poor ventilation can lead to moisture issues and mold but is less directly related to delamination compared to moisture ingress and poor resin curing.

3 / 4

Which part of the underwater section of a glass reinforced plastic (GRP) hull is most commonly affected by osmotic blisters?

B. The stern and the transom.

A. The keel and the areas around the bilge.

D. The midship section and areas around the strakes.

C. The bow and the waterline area.

Correct Answer:

A. The keel and the areas around the bilge.

Explanation:
1. Keel: The keel area is often the most exposed part of the hull to water, making it more susceptible to osmotic blisters. The constant contact with water and potential for damage or wear in this area increase the risk of moisture ingress.
2. Areas around the bilge: These areas are prone to moisture accumulation due to water ingress and drainage, which can contribute to osmotic blistering. The bilge area is also where water often collects and where hull damage is more common, leading to increased risk of blisters.

Incorrect Answers:

B. The stern and the transom.

Why it's incorrect:
1. Stern: While the stern and transom can be exposed to water, they are less commonly affected by osmotic blisters compared to the keel and bilge areas. The stern area is typically less in contact with water over time compared to the keel.
2. Transom: The transom is generally less susceptible to osmotic blisters because it is not as frequently immersed in water as other parts of the hull, particularly the keel.

C. The bow and the waterline area.

Why it's incorrect:
1. Bow: Although the bow is submerged and exposed to water, osmotic blisters are more commonly found in areas like the keel and bilge where water is more consistently in contact with the hull.
2. Waterline area: The waterline area can be affected by blisters but is less commonly affected compared to the keel and bilge areas. Blisters are more prevalent where water exposure is more direct and prolonged.

D. The midship section and areas around the strakes.

Why it's incorrect:
1. Midship section: This area is less commonly affected by osmotic blisters compared to the keel and bilge. The midship section is not in constant contact with water like the keel is.
2. Areas around the strakes: Strakes are structural features that can be affected by various forms of damage, but osmotic blisters are typically more common in areas like the keel and bilge where moisture exposure is more direct.

Correct Answer:

A. The keel and the areas around the bilge.

Explanation:
1. Keel: The keel area is often the most exposed part of the hull to water, making it more susceptible to osmotic blisters. The constant contact with water and potential for damage or wear in this area increase the risk of moisture ingress.
2. Areas around the bilge: These areas are prone to moisture accumulation due to water ingress and drainage, which can contribute to osmotic blistering. The bilge area is also where water often collects and where hull damage is more common, leading to increased risk of blisters.

Incorrect Answers:

B. The stern and the transom.

Why it's incorrect:
1. Stern: While the stern and transom can be exposed to water, they are less commonly affected by osmotic blisters compared to the keel and bilge areas. The stern area is typically less in contact with water over time compared to the keel.
2. Transom: The transom is generally less susceptible to osmotic blisters because it is not as frequently immersed in water as other parts of the hull, particularly the keel.

C. The bow and the waterline area.

Why it's incorrect:
1. Bow: Although the bow is submerged and exposed to water, osmotic blisters are more commonly found in areas like the keel and bilge where water is more consistently in contact with the hull.
2. Waterline area: The waterline area can be affected by blisters but is less commonly affected compared to the keel and bilge areas. Blisters are more prevalent where water exposure is more direct and prolonged.

D. The midship section and areas around the strakes.

Why it's incorrect:
1. Midship section: This area is less commonly affected by osmotic blisters compared to the keel and bilge. The midship section is not in constant contact with water like the keel is.
2. Areas around the strakes: Strakes are structural features that can be affected by various forms of damage, but osmotic blisters are typically more common in areas like the keel and bilge where moisture exposure is more direct.

4 / 4

Which of the following are three causes of osmotic blisters in glass reinforced plastic (GRP) hulls?

B. Excessive paint thickness, incorrect hull shape, and poor surface cleaning.

D. Frequent washing with harsh chemicals, inadequate hull ventilation, and incorrect storage conditions.

C. Excessive use of anti-fouling coatings, improper adhesive application, and high ambient temperatures during construction.

A. Inadequate gelcoat thickness, high moisture content in the hull, and poor bonding between laminate layers.

Correct Answer:

A. Inadequate gelcoat thickness, high moisture content in the hull, and poor bonding between laminate layers.

Explanation:
1. Inadequate gelcoat thickness: The gelcoat acts as a barrier to moisture ingress. If it is too thin or improperly applied, moisture can penetrate through to the laminate layers, leading to osmotic blistering.
2. High moisture content in the hull: Moisture ingress into the laminate layers causes osmotic blistering. When water is trapped within the laminate, it creates pressure and forms blisters in the gelcoat.
3. Poor bonding between laminate layers: If the bond between the laminate layers is weak, moisture can infiltrate the layers more easily, leading to the formation of osmotic blisters. Proper bonding is crucial for preventing moisture-related damage.

Incorrect Answers:

B. Excessive paint thickness, incorrect hull shape, and poor surface cleaning.

Why it's incorrect:
1. Excessive paint thickness: While excessive paint thickness can affect the hull’s appearance and performance, it does not directly cause osmotic blisters. Osmosis is more related to the laminate layers and moisture ingress rather than paint.
2. Incorrect hull shape: Hull shape issues can affect performance and structural integrity but do not directly cause osmotic blisters, which are more related to moisture penetration and laminate issues.
3. Poor surface cleaning: Poor cleaning can affect adhesion and aesthetics but does not directly contribute to the formation of osmotic blisters, which are primarily caused by moisture infiltration and laminate issues.

C. Excessive use of anti-fouling coatings, improper adhesive application, and high ambient temperatures during construction.

Why it's incorrect:
1. Excessive use of anti-fouling coatings: Anti-fouling coatings are used to prevent marine growth and do not cause osmotic blisters. They can impact the surface but are not a direct cause of osmotic issues.
2. Improper adhesive application: Adhesive application issues are more related to bonding materials rather than causing osmotic blisters. Osmotic blisters result from moisture infiltration within the laminate.
3. High ambient temperatures during construction: While high temperatures can affect curing, they are not a direct cause of osmotic blisters. Osmosis is related to moisture ingress and gelcoat issues rather than temperature alone.

D. Frequent washing with harsh chemicals, inadequate hull ventilation, and incorrect storage conditions.

Why it's incorrect:
1. Frequent washing with harsh chemicals: This can damage the surface but does not directly lead to osmotic blisters, which are caused by moisture penetrating the laminate.
2. Inadequate hull ventilation: Poor ventilation can lead to moisture buildup but is not as directly linked to osmotic blisters as the other factors listed in option A.
3. Incorrect storage conditions: While storage conditions can affect the overall condition of the hull, osmotic blisters are primarily related to moisture ingress through the laminate and gelcoat rather than storage alone.

Correct Answer:

A. Inadequate gelcoat thickness, high moisture content in the hull, and poor bonding between laminate layers.

Explanation:
1. Inadequate gelcoat thickness: The gelcoat acts as a barrier to moisture ingress. If it is too thin or improperly applied, moisture can penetrate through to the laminate layers, leading to osmotic blistering.
2. High moisture content in the hull: Moisture ingress into the laminate layers causes osmotic blistering. When water is trapped within the laminate, it creates pressure and forms blisters in the gelcoat.
3. Poor bonding between laminate layers: If the bond between the laminate layers is weak, moisture can infiltrate the layers more easily, leading to the formation of osmotic blisters. Proper bonding is crucial for preventing moisture-related damage.

Incorrect Answers:

B. Excessive paint thickness, incorrect hull shape, and poor surface cleaning.

Why it's incorrect:
1. Excessive paint thickness: While excessive paint thickness can affect the hull’s appearance and performance, it does not directly cause osmotic blisters. Osmosis is more related to the laminate layers and moisture ingress rather than paint.
2. Incorrect hull shape: Hull shape issues can affect performance and structural integrity but do not directly cause osmotic blisters, which are more related to moisture penetration and laminate issues.
3. Poor surface cleaning: Poor cleaning can affect adhesion and aesthetics but does not directly contribute to the formation of osmotic blisters, which are primarily caused by moisture infiltration and laminate issues.

C. Excessive use of anti-fouling coatings, improper adhesive application, and high ambient temperatures during construction.

Why it's incorrect:
1. Excessive use of anti-fouling coatings: Anti-fouling coatings are used to prevent marine growth and do not cause osmotic blisters. They can impact the surface but are not a direct cause of osmotic issues.
2. Improper adhesive application: Adhesive application issues are more related to bonding materials rather than causing osmotic blisters. Osmotic blisters result from moisture infiltration within the laminate.
3. High ambient temperatures during construction: While high temperatures can affect curing, they are not a direct cause of osmotic blisters. Osmosis is related to moisture ingress and gelcoat issues rather than temperature alone.

D. Frequent washing with harsh chemicals, inadequate hull ventilation, and incorrect storage conditions.

Why it's incorrect:
1. Frequent washing with harsh chemicals: This can damage the surface but does not directly lead to osmotic blisters, which are caused by moisture penetrating the laminate.
2. Inadequate hull ventilation: Poor ventilation can lead to moisture buildup but is not as directly linked to osmotic blisters as the other factors listed in option A.
3. Incorrect storage conditions: While storage conditions can affect the overall condition of the hull, osmotic blisters are primarily related to moisture ingress through the laminate and gelcoat rather than storage alone.

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