Peace of Mind Below the Waterline

The SUPERIOR Locking Nut



Standard propellers nuts often come loose resulting in a vibration, cracked shaft, or loss of a propeller.

close up of rusted and weathered propeller nut
circle highlighting crack on propeller shaft

With the Prop-Tight Locking Nut, your propeller will stay securely in place.

close up of prop tight propeller locking nut
close up of prop tight propeller locking nut on propeller of boat out of water

Based on the proven castle nut and cotter pin combination, the Prop-Tight locking nut system will keep your propeller securely in place. With its patented multiple slots, Prop-Tight Nuts are easily installed by the boatyard or owner-operator. Although Prop-Tight Nuts cost a little more than standard nuts, they won’t come loose causing damage to your shaft or possible loss of a propeller. Prop-Tight Nuts are available for all popular shaft sizes and sold online or through reputable dealers and boatyards.

What People Are Saying

large ocean yacht cruising at sunset

When hauling our boat on different occasions, we discovered a loose propeller two different times. After some research we decided to install the Prop-Tight Locking Nut System. The first thing I noticed was the quality of machine work and that they were made of Nibral. With their design incorporating multi position cotter pin slots, there is no chance of the nuts backing off to produce any more loose propellers.

Fort Lauderdale, FL
large crew boat docked next to several other crew boats

After having some issues over the years with loose propeller nuts and cracked shafts in the keyway, we have found our solution. We came across Prop-Tight Nuts and have now installed them on all our crew boats ranging from 50’ to 115’. We have thus eliminated these issues for our Port Engineers and, more importantly, have removed the cost of additional shafts and unwanted haul outs from our bottom line. A very well made, Made in the USA product.

Delaware Bay Launch Service
Milford, DE
large ocean yacht cruising with mountainous coastline in background

Throughout my career, I have had propeller nuts back off on occasion. I no longer have that concern now that we installed Prop-Tight Nuts. A great design that gives me one less thing to worry about while traveling or fishing.

Road Harbor
37’ rybovich power boat cruising on open water

During a four-day cruise on the St. John’s River with our boat club, the propeller backed off my boat while in reverse. Luckily, I was able to borrow a propeller and finish the cruise. A few years later, I saw the Prop-Tight Locking Nut System and ordered a set for my 37’ Rybovich and my 30’ Whiticar Walk-Around. Did I mention new propellers aren’t cheap!

Palm Beach, FL
45' ocean yacht with many fishing poles cruising on the ocean

After having my old propeller nuts come loose years ago on a 100-mile trip from Barnegat Inlet to Ocean City, Maryland, I now have peace of mind after installing Prop-tight Locking Nuts on my 45’ Ocean Yacht two years ago. This past month we fished two tournaments and put over 1500 miles on the boat and it’s one less thing to worry about going wrong when I’m 80 miles offshore. I will never own another boat without Prop-Tight Nuts on them.

Prime Time Sportfishing
Big Game Fishing Journal
wave dancer power boat at marina dock

For the first time in 19 years the propeller nuts on my starboard shaft didn’t loosen thanks to Prop-Tight Locking Nuts. Your system was easy to install, the craftsmanship is great, and it really works.

Wave Dancer
Atlantic Highlands, NJ
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