AME 5 Q7

1 / 3

What is the term "root whitening" in glass reinforced plastic (GRP) hull construction, and where is it most likely to occur?

C. Root whitening is the effect of resin bleeding through the laminate, typically seen in the transom and stern areas where construction materials are poorly bonded.

D. Root whitening is the formation of white patches or discoloration in the laminate due to stress, most frequently found in the midship section and areas around the strakes.

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.

B. Root whitening describes a pattern of cracking in the laminate layers, most likely to occur in the keel and bilge areas where there is excessive moisture exposure.

Correct Answer:

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.

Explanation:
1. Root whitening: This term describes the phenomenon where the gelcoat layer of a GRP hull develops a white, faded appearance. It is caused by the degradation of the gelcoat due to prolonged exposure to ultraviolet (UV) light and environmental conditions.
2. Waterline and UV exposure: These areas are particularly susceptible to root whitening because they are frequently exposed to sunlight and the environment. The waterline, in particular, is a common location for this issue due to its constant exposure to varying water conditions and UV radiation.

Incorrect Answers:

B. Root whitening describes a pattern of cracking in the laminate layers, most likely to occur in the keel and bilge areas where there is excessive moisture exposure.

Why it's incorrect:
1. Pattern of cracking: Root whitening is not related to cracking in the laminate layers. Instead, it concerns the discoloration or fading of the gelcoat surface.
2. Keel and bilge areas: While these areas are prone to other issues like moisture damage, root whitening specifically affects the gelcoat layer exposed to UV radiation, rather than areas affected by moisture and structural stress.

C. Root whitening is the effect of resin bleeding through the laminate, typically seen in the transom and stern areas where construction materials are poorly bonded.

Why it's incorrect:
1. Resin bleeding: Root whitening does not involve resin bleeding through the laminate. It is related to the degradation of the gelcoat layer.
2. Transom and stern: Root whitening is more commonly associated with UV exposure around the waterline and hull, rather than specific construction issues or bonding problems in the transom and stern areas.

D. Root whitening is the formation of white patches or discoloration in the laminate due to stress, most frequently found in the midship section and areas around the strakes.

Why it's incorrect:
1. White patches due to stress: Root whitening is not related to stress-induced discoloration in the laminate. It specifically involves the degradation of the gelcoat layer due to UV exposure.
2. Midship section and strakes: While stress and impact can cause issues in these areas, root whitening is most commonly associated with UV exposure around the waterline and hull, rather than specific stress-related discoloration in the midship or strake areas.

Correct Answer:

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.

Explanation:
1. Root whitening: This term describes the phenomenon where the gelcoat layer of a GRP hull develops a white, faded appearance. It is caused by the degradation of the gelcoat due to prolonged exposure to ultraviolet (UV) light and environmental conditions.
2. Waterline and UV exposure: These areas are particularly susceptible to root whitening because they are frequently exposed to sunlight and the environment. The waterline, in particular, is a common location for this issue due to its constant exposure to varying water conditions and UV radiation.

Incorrect Answers:

B. Root whitening describes a pattern of cracking in the laminate layers, most likely to occur in the keel and bilge areas where there is excessive moisture exposure.

Why it's incorrect:
1. Pattern of cracking: Root whitening is not related to cracking in the laminate layers. Instead, it concerns the discoloration or fading of the gelcoat surface.
2. Keel and bilge areas: While these areas are prone to other issues like moisture damage, root whitening specifically affects the gelcoat layer exposed to UV radiation, rather than areas affected by moisture and structural stress.

C. Root whitening is the effect of resin bleeding through the laminate, typically seen in the transom and stern areas where construction materials are poorly bonded.

Why it's incorrect:
1. Resin bleeding: Root whitening does not involve resin bleeding through the laminate. It is related to the degradation of the gelcoat layer.
2. Transom and stern: Root whitening is more commonly associated with UV exposure around the waterline and hull, rather than specific construction issues or bonding problems in the transom and stern areas.

D. Root whitening is the formation of white patches or discoloration in the laminate due to stress, most frequently found in the midship section and areas around the strakes.

Why it's incorrect:
1. White patches due to stress: Root whitening is not related to stress-induced discoloration in the laminate. It specifically involves the degradation of the gelcoat layer due to UV exposure.
2. Midship section and strakes: While stress and impact can cause issues in these areas, root whitening is most commonly associated with UV exposure around the waterline and hull, rather than specific stress-related discoloration in the midship or strake areas.

2 / 3

Which of the following are two possible actions to take if root whitening is discovered in a glass reinforced plastic (GRP) hull?

D. Replace the laminate layers and adjust the hull shape for better load distribution.

B. Increase the anti-fouling coating thickness and improve hull ventilation.

A. Reapply a new gelcoat layer and perform a thorough inspection to ensure UV protection.

C. Apply a fresh layer of sealant and inspect the hull for moisture ingress.

Correct Answer:

A. Reapply a new gelcoat layer and perform a thorough inspection to ensure UV protection.

Explanation:
1. Reapply a new gelcoat layer: Since root whitening is caused by the degradation of the existing gelcoat due to UV exposure, applying a new gelcoat layer can restore the protective barrier and improve the hull's appearance.
2. Perform a thorough inspection to ensure UV protection: Ensuring proper UV protection involves checking that the gelcoat is adequately applied and considering future protective measures to prevent further degradation, such as applying UV-resistant coatings.

Incorrect Answers:

B. Increase the anti-fouling coating thickness and improve hull ventilation.

Why it's incorrect:
1. Increase anti-fouling coating thickness: Anti-fouling coatings are used to prevent marine growth and do not address the root cause of root whitening, which is related to UV degradation of the gelcoat.
2. Improve hull ventilation: While ventilation is important for preventing moisture issues, it does not directly address root whitening, which is primarily caused by UV exposure and gelcoat degradation.

C. Apply a fresh layer of sealant and inspect the hull for moisture ingress.

Why it's incorrect:
1. Apply a fresh layer of sealant: Sealants are used to seal joints and fittings, but they do not resolve root whitening. Root whitening involves the gelcoat layer, not sealants.
2. Inspect for moisture ingress: While inspecting for moisture ingress is important for other issues, it does not directly address the UV degradation of the gelcoat that causes root whitening.

D. Replace the laminate layers and adjust the hull shape for better load distribution.

Why it's incorrect:
1. Replace the laminate layers: This action is excessive for addressing root whitening. The issue is with the gelcoat layer, not the laminate layers.
2. Adjust the hull shape: Changing the hull shape affects structural and performance characteristics but does not address the cosmetic issue of root whitening caused by UV exposure.

Correct Answer:

A. Reapply a new gelcoat layer and perform a thorough inspection to ensure UV protection.

Explanation:
1. Reapply a new gelcoat layer: Since root whitening is caused by the degradation of the existing gelcoat due to UV exposure, applying a new gelcoat layer can restore the protective barrier and improve the hull's appearance.
2. Perform a thorough inspection to ensure UV protection: Ensuring proper UV protection involves checking that the gelcoat is adequately applied and considering future protective measures to prevent further degradation, such as applying UV-resistant coatings.

Incorrect Answers:

B. Increase the anti-fouling coating thickness and improve hull ventilation.

Why it's incorrect:
1. Increase anti-fouling coating thickness: Anti-fouling coatings are used to prevent marine growth and do not address the root cause of root whitening, which is related to UV degradation of the gelcoat.
2. Improve hull ventilation: While ventilation is important for preventing moisture issues, it does not directly address root whitening, which is primarily caused by UV exposure and gelcoat degradation.

C. Apply a fresh layer of sealant and inspect the hull for moisture ingress.

Why it's incorrect:
1. Apply a fresh layer of sealant: Sealants are used to seal joints and fittings, but they do not resolve root whitening. Root whitening involves the gelcoat layer, not sealants.
2. Inspect for moisture ingress: While inspecting for moisture ingress is important for other issues, it does not directly address the UV degradation of the gelcoat that causes root whitening.

D. Replace the laminate layers and adjust the hull shape for better load distribution.

Why it's incorrect:
1. Replace the laminate layers: This action is excessive for addressing root whitening. The issue is with the gelcoat layer, not the laminate layers.
2. Adjust the hull shape: Changing the hull shape affects structural and performance characteristics but does not address the cosmetic issue of root whitening caused by UV exposure.

3 / 3

Which of the following are two possible reasons for root whitening in glass reinforced plastic (GRP) hull construction?

D. Low-quality resin used in the laminate and high ambient temperatures during curing.

B. Excessive use of anti-fouling coatings and inadequate ventilation during construction.

C. Improper application of sealants and excessive moisture ingress in the hull.

A. Prolonged exposure to ultraviolet (UV) light and degradation of the gelcoat layer due to environmental conditions.

Correct Answer:

A. Prolonged exposure to ultraviolet (UV) light and degradation of the gelcoat layer due to environmental conditions.

Explanation:
1. Prolonged exposure to UV light: The gelcoat layer of a GRP hull is directly exposed to sunlight, which contains UV rays. Over time, UV exposure breaks down the gelcoat, causing it to lose color and become discolored or faded, which is known as root whitening.
2. Degradation of the gelcoat layer: Environmental conditions such as UV radiation, moisture, and temperature fluctuations contribute to the deterioration of the gelcoat layer. As the gelcoat degrades, it becomes more prone to discoloration, resulting in root whitening.

Incorrect Answers:

B. Excessive use of anti-fouling coatings and inadequate ventilation during construction.

Why it's incorrect:
1. Excessive use of anti-fouling coatings: Anti-fouling coatings are used to prevent marine growth and are not related to root whitening. They do not cause the gelcoat to degrade or change color.
2. Inadequate ventilation during construction: While poor ventilation can affect the curing process, it does not directly cause root whitening. Root whitening is more related to UV exposure and environmental degradation of the gelcoat.

C. Improper application of sealants and excessive moisture ingress in the hull.

Why it's incorrect:
1. Improper application of sealants: Sealants are used to seal joints and fittings but do not cause root whitening. Root whitening involves the degradation of the gelcoat layer, not issues with sealants.
2. Excessive moisture ingress: Moisture ingress can lead to problems such as osmotic blisters or delamination but is not directly related to root whitening, which is caused by UV exposure and environmental conditions.

D. Low-quality resin used in the laminate and high ambient temperatures during curing.

Why it's incorrect:
1. Low-quality resin: Low-quality resin affects the overall strength and durability of the laminate but does not specifically cause root whitening. Root whitening is related to the degradation of the gelcoat layer, not the resin used in the laminate.
2. High ambient temperatures during curing: While temperature can impact curing, root whitening is primarily caused by UV degradation of the gelcoat layer rather than the curing process itself.

Correct Answer:

A. Prolonged exposure to ultraviolet (UV) light and degradation of the gelcoat layer due to environmental conditions.

Explanation:
1. Prolonged exposure to UV light: The gelcoat layer of a GRP hull is directly exposed to sunlight, which contains UV rays. Over time, UV exposure breaks down the gelcoat, causing it to lose color and become discolored or faded, which is known as root whitening.
2. Degradation of the gelcoat layer: Environmental conditions such as UV radiation, moisture, and temperature fluctuations contribute to the deterioration of the gelcoat layer. As the gelcoat degrades, it becomes more prone to discoloration, resulting in root whitening.

Incorrect Answers:

B. Excessive use of anti-fouling coatings and inadequate ventilation during construction.

Why it's incorrect:
1. Excessive use of anti-fouling coatings: Anti-fouling coatings are used to prevent marine growth and are not related to root whitening. They do not cause the gelcoat to degrade or change color.
2. Inadequate ventilation during construction: While poor ventilation can affect the curing process, it does not directly cause root whitening. Root whitening is more related to UV exposure and environmental degradation of the gelcoat.

C. Improper application of sealants and excessive moisture ingress in the hull.

Why it's incorrect:
1. Improper application of sealants: Sealants are used to seal joints and fittings but do not cause root whitening. Root whitening involves the degradation of the gelcoat layer, not issues with sealants.
2. Excessive moisture ingress: Moisture ingress can lead to problems such as osmotic blisters or delamination but is not directly related to root whitening, which is caused by UV exposure and environmental conditions.

D. Low-quality resin used in the laminate and high ambient temperatures during curing.

Why it's incorrect:
1. Low-quality resin: Low-quality resin affects the overall strength and durability of the laminate but does not specifically cause root whitening. Root whitening is related to the degradation of the gelcoat layer, not the resin used in the laminate.
2. High ambient temperatures during curing: While temperature can impact curing, root whitening is primarily caused by UV degradation of the gelcoat layer rather than the curing process itself.

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