ArticleBoatingService Repair


Imagine yourself cruising through the open ocean while enjoying the sun on your skin and wind in your hair. With cool drink in the cup holder and fish in the box, it doesn’t get much better. All of a sudden your boat begins to slow and come off plane while your engine RPMs continue to rev up. Welcome to the spun hub club.


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Dead in the water is a situation no boater wants to be in. Photo: istockphoto/thinkstock

If this is the first time you’ve experienced this misfortune, then you might be under the assumption that you are experiencing a malfunction with the outboard motor. However, it’s all about the prop. The latest outboard powerhouses are impressively equipped and provide serious output. Striking an object in the water at any speed can be damaging to your lower unit and gear case, but that’s what a prop’s hub is designed for. Because of the immense torque transferred to the drive shaft, propellers must be designed with a hub insert to withstand the pressure. These critical elements protect your lower unit’s integrity by serving as the weakest link if your prop was to strike an object or become entangled in unforgiving debris. When the bond is broken between prop and hub, the shaft will spin but the propeller will not.

Not much is worse than a mechanical failure on the water, but with a few basic tools and spare parts you will be able to overcome this serious setback.

Prop hub inserts were one made exclusively out of rubber, but today’s outboards produce high temperature combustion and exhaust that can destroy rubber inserts. To keep outboards running smooth, manufacturers now produce prop hubs out of high tensile polycarbonate and composite materials, but that doesn’t mean you’re completely protected. While there are a host of obstructions one must avoid in the water, it’s not only direct impact that will result in a spun hub. Years of wear and tear will make the insert brittle and may result in its eventual failure. Once this vital assembly has been separated from the prop you will be dead in the water. There might be enough friction between the two where you can reach idle speed, but any additional increase in RPM will cause the prop to slip. From here your options are limited to idling home, calling for a tow, or replacing the prop on the water.

If you’re fishing abroad or routinely head miles over the horizon, it may be in your best interest to carry a spare prop, in addition to a basic tool kit and essential spares. A spare prop isn’t cheap, but if you fish from a single outboard powered vessel and don’t carry a spare you’re simply asking for trouble. A propeller is the single most critical factor for transferring power to on-the-water performance and it is unadvisable to head offshore without a spare prop kit. To get going after spinning a hub you’ll need a new prop and prop wrench, but you should also have an extra nut and cotter pin. Additional items that could get you up and running in the event of an emergency include spare fuel filters, engine oil, spark plugs and fuses.

Propeller hubs are inexpensive to repair, but it’s really not a do it yourself project, rather one that should be accomplished by a local marine mechanic. However, you can change a prop on the water and get back on your way. If you’ve spun a hub inshore and can reach a sandy shoreline, then you can easily change your prop with little hassle. Anglers fishing offshore will have a greater challenge on their hands, but one that’s completely feasible. After tilting the engine, the first step is to remove the cotter pin on the prop shaft with a pair of needle nose pliers. From here, using the appropriately sized prop wrench you need to remove the prop nut. You may have to secure the prop with a small 2×4 to do so. Next, remove the washer and prop. If the prop is stubborn, lightly tapping the back of it with a rubber mallet often does the trick.

At this point, the new prop should slide right on the prop shaft. Reinstall the washer, prop nut and cotter pin and you are back in business. It sounds rather painless, but you’ll either need to crawl over the cowlings and hang off the transom, or fully submerge yourself in the water. Either way, it will be a tricky dance as you negotiate a pitching and rolling boat without losing your balance or dropping tools and spare parts in the water. Sounds sketchy, but when you’re miles offshore your choices are limited.

If you’re able to make it back to the dock or shoreline, you’ll want to inspect the lower unit seal and also apply fresh grease to the shaft before installing a new prop. If you’re bobbing around in the ocean it’s understandable that your main objective is to simply install the prop and get back on your way. This is not the time to complete routine maintenance and inspections.

Not much is worse than a mechanical failure on the water, but with a few basic tools and spare parts you will be able to overcome this serious setback. Good luck and remember to never underestimate the harsh marine environment. Spend enough time on the water and you’ll learn that anything that can go wrong eventually will!