06/17/2026
Help help, "I'm sinking"-Emergency Lift at the boat yard today..
Here's why...
Using standard plastic (like nylon) for thru-hulls below the waterline is dangerous because they become brittle with age, are vulnerable to UV degradation, and have low impact resistance. A sheared fitting or cracked fl**ge allows water to flood the boat, making it the one of the leading causes of boats sinking.
The primary risks of using standard plastic thru-hulls include: Brittleness and UV
Damage:
Ordinary plastics, especially nylon, degrade from exposure to sunlight and temperature changes, causing them to crack or snap.
Shear Stress: The weight of attached hoses and constant hull vibration can snap the fitting right at the fl**ge, creating an open hole.
Impact and Thread Failure: Standard plastic is less forgiving during installation. Over-tightening hose clamps or a minor strike against a dock can cause hidden cracks.
Approved Alternatives for Below the Water line for critical below-waterline fittings (intakes, drains, and their corresponding seacocks), marine standards require robust materials such as
Bronze:
The industry's gold standard for durability, strength, and corrosion resistance.
Marelon: A high-tech, fiberglass-reinforced polymer composite specifically engineered to be completely corrosion-proof and strong enough for underwater use.
Unfortunately this thru hull was attached to the waste holding tank and it's a super disgusting smelly job to clean up.
