MST MST Hull & Fiberglass Repair

Question 1

What is the correct ratio of hardener to resin when mixing standard polyester laminating resin for a fiberglass repair?

Accepted Answer

1–2% MEKP by weight

Answer

Standard polyester resin requires 1–2% methyl ethyl ketone peroxide (MEKP) catalyst by weight for proper cure.

Question 2

Before applying a fiberglass patch, the damaged area should be ground to what profile?

Accepted Answer

A feathered 12:1 taper

Answer

A 12:1 taper grind ensures adequate bonding area and distributes stress across the repaired laminate.

Question 3

Which type of fiberglass cloth is preferred for above-waterline cosmetic repairs due to its smooth surface finish?

Accepted Answer

Plain weave cloth

Answer

Plain weave fiberglass cloth sands to a finer, smoother finish and is best suited for cosmetic above-waterline repairs.

Question 4

Osmotic blistering on a fiberglass hull is caused primarily by what process?

Accepted Answer

Water migrating through the gel coat into the laminate

Answer

Osmosis occurs when water molecules permeate the gel coat and react with water-soluble compounds in the laminate, forming acidic fluid-filled blisters.

Question 5

When repairing an osmotic blister, what is the first step after opening the blister?

Accepted Answer

Allow the hull to dry thoroughly for weeks

Answer

The hull must dry completely — often for 30–90 days — before epoxy barrier coat is applied to prevent moisture from being sealed in.

(MST) Marine Service Technician Practice Test

(MST) Marine Service Technician Practice Test

MST MST Hull & Fiberglass Repair