Conveyor-DiagramFuel theft is on the rise, forcing boaters to look for the best means of protection, and they are finding it with the Tank Lock™ durable locking fill cap.  Lock your boat's fuel, water, and waste tank --- securely.

The patented design and quality manufacturing of our Tank Lock sets a standard unequaled by plastic and rubber locks, and provides a high quality solid stainless steel locking cap to prevent fuel theft. Buy Tank Lock online now.

The Tank Lock:

  • Locks a boat's fuel, water, and waste supply.
  • A product giving you self security and peace of mind.
  • The two piece fuel cap installs in just minutes.
  • Durable and strong for a long service life.
  • The only locking fuel cap offered in 5 standard sizes.
  • Developed by an avid boater...for boaters.
  • Made in the U.S.A. of solid high-grade stainless steel.

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We recommend measuring the threads and cap of your existing fill with a set of calipers for accuracy.  Most marinas and auto part stores will gladly help you with this.

There are five different tank lock systems, based on size, so it is important that you order the correct size to match your existing setup.  See our size help page HERE

Along with ordering online from the Tank Lock website, the Tank Lock is also available for purchase at many boating recreation stores and marinas across the United States.

The most updated list of dealers that carry the Tank Lock are listed HERE

Installing the Tank Lock takes only a matter of seconds to complete and only requires a Phillips screwdriver and standard deckfill key / L key.  

Just unscrew the chain from your old fill cap and attach it to the Tank Lock with the special screw provided.  Tighten into deck fill with your L key and you're all set!

Tank Lock support stands can be ordered 24 hours/day online at or by phone at 866-865-5625

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