What Is Outdrive On A Boat?

When buying a boat, it’s crucial to know the boat engine type. The outdrive mounted behind the boat hull is easy to steer.

Most of us consider the materials used to make the boat, top speed, features, and passenger capacity before anything else. The type of engine on the vessel plays a vital role in how your boat is operated. But what is outdrive on a boat?

Outdrives are propulsion mechanisms that enable boats with an inboard engine to operate an external drive. The system is usually attached to the vessel's rear and efficiently helps drive a boat through the water.

Outdrive boats are built for those who want to have an adventurous life on the water. They are perfect for fishing, diving, sailing, or cruising with friends and family. But what makes them different from other types of engine systems?

Stick around as we explore the world of outdrives, so you know what you will be getting with a sterndrive boat.

‍What is Outdrive?

An outdrive motor is essentially the bottom half of an outboard connected to the inboard engine - usually a four-stroke automotive engine located in the hull. The outdrive enables the transmission and steering of the propeller outside the hull.

The outdrive may be connected with the inboard stern engine or have an outboard motor mounted on the boat’s rear end

The benefits of outdrives arise from the design of inboard/outboard (I/O) engines. A driveshaft runs from the engine through the hull to the upper half of an outdrive. The top part is connected to the bottom half by two 90-degree gearboxes, which transmit the power to the propeller.

Thanks to the efficient design of outdrives, they produce less drag and consume less fuel than a shaft drive. If these sound like something you want to achieve, you can have one cleverly outfitted to your inboard-driven boat.

What Does an Outdrive Do?

This marine propulsion system handles both transmission and propulsion tasks. No rudder is required to steer the boat. The entire drive unit is rotated from side to side to control direction.

Nonetheless, the outdrive can also be trimmed up to avoid striking anything in shallow waters. This flexibility further allows the boat to be trailered more easily. If this feature weren't present, you'd risk damaging the propeller and other components. It also helps prevent fouling between uses.

Common Outdrive Problems

As with any watercraft, outdrives engines develop problems too. Some types are affected a little bit more than others. Anyone who's owned a boat that runs on an inboard/outboard (I/O) engine will tell you certain issues are common for all outdrives. A few are brand-specific.

Read on as we look at three of the most prevalent issues that affect outdrive systems.

Physical Damage

Should your drive unit encounter an obstruction underwater, expect some damage. Some boaters have had the entire drive unit pop out of the engine after accidentally hitting a submerged rock or stump.

Even a mud bank is enough to cause substantial damage.

Corrosion Issues

Saltwater and heat are the biggest culprits of outdrive weathering, especially if you keep your boat moored on the dock for extended periods.

Most corrosion occurs in the lower exhaust housing. It’s where the seawater comes into contact with hot gasses from the unit.

Mechanical Problems

One of the most common mechanical failures you may have to deal with is linkage failures. Most outdrive users report a delay after moving the throttle lever from neutral to a forward drive position.

After about a minute, there is a 'clink' sound before the vessel conforms to the set gear. The same also occurs when you return to neutral.

Inspect the linkage cable and ensure it is firmly clamped to the outdrive. Then drain the oil from the outdrive and check for anomalies. If there's a noticeable change, the gear oil could be burning due to high heat produced from a slipping clutch. The best solution would be to perform a linkage adjustment.

Can You Beach an Outdrive?

Yes, you can beach an outdrive—just don't let it bang off the bottom. Outdrive units are flexible and can be moved up and down depending on the depth of the water.

Beaching is not to be confused with grounding. The latter is when the vessel is completely taken out of the water, while beaching involves pitching your boat so it sits on the sand at low tide. Learning how to beach an outdrive is an essential skill for situations when you'd like to go onshore.

Process of Beaching

Step 1: Begin by reducing the speed, so the boat idles towards the shore.

Step 2: Have someone sit in the stern section of the craft with the bow anchor until you get to where the water is waist-high.

Step 3: Turn off the engine and trim the motor upwards as the bow nuzzles into the sand.

How to Awaken Your Outdrive After Winter

Waking up your outdrive motor from a deep winter slumber is substantial work. It would help inspect the outdrive, gears, propellor, and lube. Your best bet is to call in the experts, but a basic knowledge of the working mechanism of watercraft will suffice if you DIY.

If you live in areas with substantial snowfall and freezing temperatures, you already understand how much damage ice can do on a boat. Thus, we are advised to winterize the outdrive plus the engine. Typically, this involves treating the engine with fogging oil, changing the inboard/outboard's engine and gear lube oil.

Follow this simple guide to see you through:

Examine the Outdrive

Carefully examine all outdrive components for faults. Are there cracks on the driveshaft and bellows or leaks from the cylinders of the trim/tilt reservoir? You must remove all damaged parts.

And if you find one cracked bellow, you have to replace all the bellows on the boat. A defective bellow could flood your boat, capsizing it.

Check the Propellor

Detach the propeller and grease the shaft. Inspect it for bends before reinstalling the prop. If there is physical damage, you may have to purchase and replace it with a new one.

Change the Gear Oil

Depending on the design of your outdrive motor, perform a gear lube oil change. Refer to the boat's manual for specific instructions on how to complete this task depending on the outdrive you have.