SRT Inflatable & Rigid Hull Boats 2 — Questions and Answers
Question 1: What is the correct upstream ferry angle for an inflatable rescue boat to efficiently cross a swift current?
- 90 degrees perpendicular to the current
- 30-45 degrees angled toward the upstream bank (Correct answer)
- 60-75 degrees angled toward the downstream bank
- 15 degrees nearly parallel to the current
Correct answer: 30-45 degrees angled toward the upstream bank
A 30-45 degree upstream ferry angle allows the current to push the boat laterally while forward momentum is maintained with minimal effort against the flow.
Question 2: When an inflatable rescue boat is broached sideways against a rock, crew members should immediately:
- Lean to the downstream side away from the rock
- Jump out to lighten the load
- Lean upstream into the rock (high-side) to prevent the downstream tube from diving (Correct answer)
- Push off the rock from the downstream side with paddles
Correct answer: Lean upstream into the rock (high-side) to prevent the downstream tube from diving
High-siding by leaning to the upstream side keeps the downstream tube from diving under, which would cause the boat to wrap or flip catastrophically around the obstacle.
Question 3: When crossing an eddy line in a swiftwater rescue boat, the primary hazard to anticipate is:
- Loss of motor power due to aeration
- An abrupt change in current direction causing the boat to spin or flip (Correct answer)
- Increased hull friction from turbulent water
- GPS signal interference from spray
Correct answer: An abrupt change in current direction causing the boat to spin or flip
The sharp velocity differential across an eddy fence can quickly rotate or capsize a boat if it is not crossed at the proper angle and speed.
Question 4: A 'rooster tail' seen in a river primarily indicates:
- An area of calm, deep water suitable for boat landing
- A jet of water shooting up downstream of a submerged rock, marking a hidden hazard (Correct answer)
- The spray pattern created by a motor at high RPM
- A safe eddying current suitable for swimmer recovery
Correct answer: A jet of water shooting up downstream of a submerged rock, marking a hidden hazard
The standing wave or spray plume called a rooster tail forms on the downstream side of a submerged obstacle and warns boat operators of its presence.
Question 5: The primary structural difference between a rigid inflatable boat (RIB) and a standard inflatable rescue boat (IRB) is:
- A RIB has a solid fiberglass or aluminum hull paired with inflatable sponson tubes, while an IRB has a flexible or inflatable floor (Correct answer)
- RIBs are always motor-powered while IRBs are always paddle-powered
- RIBs are rated only for flatwater while IRBs are designed for rapids
- RIBs have a single air chamber while IRBs have multiple independent chambers
Correct answer: A RIB has a solid fiberglass or aluminum hull paired with inflatable sponson tubes, while an IRB has a flexible or inflatable floor
The rigid hull of a RIB provides structural rigidity and tracking while the inflatable sponsons (tubes) provide buoyancy and impact absorption.
Question 6: When approaching a strainer in an inflatable rescue boat, the correct crew action is to:
- Accelerate to punch through before becoming pinned
- Turn aggressively upstream and motor or paddle away immediately (Correct answer)
- Deploy an anchor to hold position while assessing passage
- Drift slowly toward the strainer to evaluate gap size
Correct answer: Turn aggressively upstream and motor or paddle away immediately
Strainers are among the most lethal hazards in swiftwater; the only appropriate boat response is immediate aggressive upstream movement to escape.
Question 7: When operating an outboard motor in a shallow, rocky rapid, why must the operator be prepared to tilt the motor quickly?
- To increase thrust by changing the propulsion angle
- To prevent cavitation in aerated whitewater
- To protect the propeller and shear pin from striking submerged rocks (Correct answer)
- To redirect the boat sideways using propeller torque
Correct answer: To protect the propeller and shear pin from striking submerged rocks
Tilting the outboard up in shallow or rocky sections protects the propeller and driveshaft from impact damage on submerged obstacles.
SRT Inflatable & Rigid Hull Boats 2
What is the correct upstream ferry angle for an inflatable rescue boat to efficiently cross a swift current?