MST MST Hull & Fiberglass Repair 2

Question 1

Delamination of a fiberglass hull is best detected using which method?

Accepted Answer

Sounding with a plastic mallet

Answer

Tapping the hull with a plastic or rubber mallet produces a dull thud over delaminated areas, compared to a sharp ring over solid laminate.

Question 2

Which type of resin provides superior adhesion and moisture resistance for structural hull repairs compared to polyester?

Accepted Answer

Epoxy resin

Answer

Epoxy resin bonds more strongly, absorbs far less water, and provides better chemical resistance than polyester for structural repairs.

Question 3

What grit sandpaper is typically used for the final prep of gel coat before applying a color-matched gel coat patch?

Accepted Answer

220–320 grit wet/dry

Answer

220–320 grit wet/dry sandpaper creates a surface profile that allows the new gel coat to bond while minimizing visible scratches.

Question 4

Why is polyvinyl alcohol (PVA) film sometimes applied over a gel coat repair?

Accepted Answer

To exclude air and allow the surface to cure fully

Answer

Polyester gel coat requires exclusion of oxygen to cure tack-free, and PVA film seals the surface from air.

Question 5

A spider crack pattern in gel coat typically indicates what underlying condition?

Accepted Answer

Impact damage or flexing stress in the laminate

Answer

Spider cracks (crazing) usually originate from an impact or chronic flexing that stresses the rigid gel coat beyond its limit.

(MST) Marine Service Technician Practice Test