SAMS - Society of Accredited Marine Surveyors Certified Hull Inspection and Materials Questions and Answers

Question 1

When performing a non-destructive test on a steel hull to determine plate thickness, which method is most commonly used by marine surveyors?

Accepted Answer

Ultrasonic Thickness Measurement (UTM)

Answer

Ultrasonic Thickness Measurement (UTM) is the standard non-destructive method for gauging the thickness of a vessel's hull plating. It works by sending a high-frequency sound wave through the material and measuring the time it takes for the echo to return, which directly corresponds to the plate's thickness. While RT, MPI, and DPI are also NDT methods used in marine surveys, they are for detecting flaws like cracks and surface defects, not for measuring material thickness.

Question 2

A surveyor is inspecting a 15-year-old fiberglass (GRP) vessel that has been kept in warm seawater. They observe numerous small blisters below the waterline that, when punctured, release an acidic, vinegar-like fluid. What is the most likely cause of this phenomenon?

Accepted Answer

Osmotic Blistering

Answer

The scenario described is a classic presentation of osmotic blistering. This occurs when water molecules slowly permeate the semi-permeable gelcoat and react with uncured resins or other soluble materials within the fiberglass laminate, creating an acidic solution that forms blisters under pressure. This process is accelerated in warm water conditions. Galvanic corrosion affects metals, and delamination from impact would typically present as a larger, more localized area of damage.

Question 3

During a survey of an aluminum-hulled vessel, which of the following findings would be of GREATEST concern regarding potential accelerated corrosion?

Accepted Answer

A bronze through-hull fitting installed without proper isolation

Answer

A bronze through-hull fitting in direct contact with an aluminum hull creates a galvanic cell, where the aluminum (the less noble metal) becomes the anode and corrodes at an accelerated rate in the presence of an electrolyte like seawater. Proper installation requires isolating dissimilar metals. Minor scratches, uniform oxidation, and a functioning anode system are less critical concerns; in fact, the anode system is designed to prevent this type of corrosion.

Question 4

A surveyor is using the percussion (hammer) testing method on a cored fiberglass deck. A sharp, solid sound is heard over most of the area, but a dull thud is noted near a stanchion base. What does this dull sound most likely indicate?

Accepted Answer

Delamination or water-saturated core material

Answer

Percussion or 'tap' testing is a common method to identify voids or delamination in composite structures. A solid, sharp sound indicates a well-bonded laminate, while a dull, hollow, or 'dead' sound suggests a void, delamination between layers, or a water-saturated (and potentially rotted) core material. The area around deck fittings like stanchions is a common location for water intrusion into the core.

Question 5

Which of the following is a primary reason for using cored composite construction in a fiberglass hull instead of solid fiberglass?

Accepted Answer

To achieve a higher stiffness-to-weight ratio

Answer

Cored composite construction, which sandwiches a lightweight core material (like balsa or foam) between layers of fiberglass, is used to create panels that are significantly stiffer and stronger for their weight compared to a solid laminate of the same weight. This allows for a lighter, more efficient, and often faster vessel. While it can sometimes be cost-effective, its primary engineering purpose is to improve the stiffness-to-weight ratio, not simply to cut costs or increase weight. Cored hulls are susceptible to water intrusion if not properly sealed.

(SAMS) Society of Accredited Marine Surveyors Certified Practice Test

(SAMS) Society of Accredited Marine Surveyors Certified Practice Test

SAMS - Society of Accredited Marine Surveyors Certified Hull Inspection and Materials Questions and Answers