🔍 Key Concepts

• Gasoline fuel tank venting requirements on small passenger vessels in 46 CFR Subchapter T • Purpose of a vent pipe U-bend and termination above the weather deck • Minimum vent pipe size and point of connection on the tank

💭 Think About

• Ask yourself why gasoline tanks must be able to freely breathe in and out, and what could happen if the vent were too small or poorly located. • Think about how rainwater or seawater might enter a vent, and what design features (like a U-bend/gooseneck and location above deck) are used to prevent that. • Consider whether a safe vent system would normally connect at the highest point of the tank or somewhere lower, and why that matters for vapors and expansion.

✅ Before You Answer

• Check in 46 CFR that there is a specific minimum vent size, often referenced to about 19 mm (3/4 in) OD tubing. • Verify that the regulations require the vent to be connected to the tank at its highest point to avoid vapor or liquid traps. • Confirm whether the rules call for the vent to terminate in a U-bend (gooseneck) above the weather deck to reduce the chance of water ingress and fuel spillage.