Hull Inspection and Materials Flashcards
7 cards from real SAMS practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Hull Inspection and Materials flashcards as text
During a haulout survey of a fiberglass vessel, what is the significance of finding osmotic blisters primarily below the static waterline but not above it?
Answer: Confirms moisture permeation requires prolonged water immersion, consistent with osmosis
Osmotic blisters occur below the waterline because sustained water contact is required for moisture to permeate and initiate the hydrolysis reaction in the laminate.
What is the primary purpose of a keelson in wooden hull construction?
Answer: To reinforce the keel from inside the hull and distribute loads
The keelson is an internal longitudinal timber bolted over the frames and keel, reinforcing the keel from inside and distributing structural loads along the hull's backbone.
When a surveyor measures hull plate thickness on a steel vessel and finds wastage exceeding what percentage of original thickness, is replacement typically recommended?
Answer: 20%
Generally, steel hull plating with wastage exceeding 20% of original thickness is considered to require repair or replacement to maintain structural integrity.
Which condition is most indicative of 'hard spots' in a fiberglass hull?
Answer: Localized cracking in the hull skin aligned with underlying bulkhead or frame positions
Hard spots occur when hull skin cracks appear in lines that mirror the position of stiff internal members (frames, bulkheads) transferring point loads into the flexible laminate.
In composite construction, what does the term 'print-through' refer to?
Answer: Telegraph of the woven fabric pattern visible through the gel coat surface
Print-through is the telegraphing of the weave pattern of underlying reinforcing fabric through the gel coat, caused by differential cure shrinkage.
A surveyor inspects a vessel and finds that the hull-to-deck joint is through-bolted and bedded with polysulfide sealant. What primary concern should the surveyor address?
Answer: The joint should be inspected for sealant failure, water intrusion, and structural fastener corrosion
The surveyor must verify that the sealant is intact, that no water intrusion has caused core saturation or fastener corrosion, as the hull-to-deck joint is a critical structural connection.
When assessing plywood used in a hull repair, what feature distinguishes marine-grade plywood from exterior-grade plywood?
Answer: Marine plywood has no voids in interior plies and uses waterproof adhesive throughout
Marine-grade plywood is manufactured with solid, void-free interior plies and waterproof (WBP) adhesive, preventing delamination and hidden voids that trap moisture.