Boat Security: Cable Locks & Trailer Hitch Locks
Most boat theft prevention is about making your rig harder to tow away and your gear harder to grab. Layer simple locks rather than relying on one.
What to Look For
Pick locks for the way your boat is actually stored: on a trailer at home, in a yard, or in a slip.
Coupler fit
Coupler locks are sized to ball sizes such as 1-7/8, 2 and 2-5/16 in. Confirm your trailer's coupler before buying.
Weather resistance
Look for covered keyways and corrosion-resistant finishes, and expect to lubricate locks used near salt water.
Layering
Combine a coupler lock with a cable lock for loose gear and a receiver lock while towing or parked.
Our Picks
A universal coupler lock for a parked trailer, an adjustable cable lock for gear, and a swivel receiver lock.
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Picks are based on manufacturer-published specifications and the buying criteria on this page, not on paid placement or hands-on lab testing. Check the listing for the current model, size and fit before you buy.
How to Choose Boat and Trailer Security
For trailered boats, much of the theft risk is the whole rig: someone backs up, drops the coupler on a ball and drives away. For boats in a slip or a yard, the risk shifts to loose gear such as small outboards, electronics, paddleboards and coolers. Good security is about matching a simple lock to each of those risks and using them every time.
Coupler locks for parked trailers
A coupler lock fills or blocks the trailer coupler so it can't be dropped onto a hitch ball. Many are sized for specific ball diameters, commonly 1-7/8 inch, 2 inch and 2-5/16 inch, while "universal" designs cover several. Check the size stamped on your coupler before buying. Coupler locks only work while the trailer is unhitched, so pair one with a wheel chock and park with the tongue facing a wall or tucked behind other vehicles where possible.
Receiver and hitch pin locks for towing
A receiver lock replaces the ordinary hitch pin and clip that hold the ball mount in your tow vehicle's receiver. It keeps your ball mount from walking off and adds a little security when you stop on the road. Match the pin diameter to your receiver class; many kits include both 1/2 inch and 5/8 inch pins.
Cable locks for gear
An adjustable braided steel cable lets you secure gear that doesn't have a dedicated lock point: a small outboard's clamp handles, kayaks and paddleboards to a rack, a cooler or fuel tank to a rail. Cable locks deter grab-and-go theft but can be cut with the right tools, so they're best for keeping honest people honest and slowing down opportunists.
Weather resistance and maintenance
Every lock near the water needs care. Choose models with covered keyways or weather caps, rinse them with fresh water after salt exposure, and use a lock-safe lubricant a few times a season. A lock that's seized when you need to leave is a lock that gets left off.
Layer it
No single lock prevents theft. Combine a coupler lock, a receiver lock while towing, cable locks for loose gear and good habits: take the ignition key and cut-off clip with you, record your hull identification number (HIN) and engine serial numbers, photograph your gear, and keep your registration information somewhere other than the boat. If you share keys with others, a key safe is better than a hidden spare.