Last Updated on June 20, 2025
This article talks about some common problems with sterndrive boat engines. While these engines have been around for a long time and offer some good things, there are a few downsides you should know about before you decide to buy a boat with one. We'll go over things like their weight, how much space they take up, and the kind of maintenance they need.
Sterndrive Boat Problems You Should Know About
Sterndrive engines have been around for a while, and they do have their good points. But it's also smart to know about the issues that can come with them. Here are some things to consider before you buy a boat with a sterndrive.
They Are Heavy and Big
One of the first things you'll notice about sterndrive engines is their size and weight. They are often based on car or truck engines, which means they are quite large. This includes big exhaust manifolds that help keep water out of the engine. Because of their width and height, they take up a lot of room in a boat. They are also heavier compared to an outboard engine with the same horsepower. So, if you're looking at a 300 horsepower engine, an outboard will have a better power-to-weight ratio than a sterndrive.
They Take Up a Lot of Storage Space
Since sterndrive engines are big, they use up a good amount of storage space inside the boat. If you compare this to a boat with an outboard engine of the same size, you'll usually find more room for other things and storage. This can be a big deal if you like to bring a lot of gear or want more open space on your boat.
More Maintenance and Repairs
Generally, an outboard engine will cost less to maintain and fix than a sterndrive. Sterndrive engines often need more oil and have more cylinders, which means more spark plugs. They might also need tune-ups more often because they have parts like a cap and rotor, unlike the solid-state ignition in outboards. They also have bellows in the drive that wear out over time, and a shift cable. All these extra parts mean more things can break or need replacing during regular maintenance.
While the costs aren't completely out of control, you can expect slightly higher maintenance and repair bills compared to an outboard. Sometimes, working on these engines can be tricky because they are in tight spaces. There have been times when parts like a starter or even spark plugs needed replacing, and the engine had to be removed just to do the work. That's a big job.
Can't Trim All the Way Out of the Water
Outboard engines can tilt all the way out of the water, which is really helpful, especially in saltwater or if you just want to keep your engine clean. But with a sterndrive, because it pivots at the waterline, you can't get the whole drive out of the water when you trim it up. In saltwater, this means the drive, with its aluminum and other metals, is exposed to more corrosion. Also, if you need to get the drive out of the water for shallow areas, it's harder. When you do trim it up, the bellows are exposed to sea creatures that might chew on them.
May Use More Fuel
Sterndrive engines tend to be larger and heavier, so they often use more fuel than an outboard with similar power. This is just how physics works. For example, a current 300 horsepower Mercury outboard has a 4.6-liter displacement, while a current 300 horsepower Mercury sterndrive is 6.2 liters. That difference in size, plus the extra weight, means more fuel consumption.
Need a Bilge Blower for Fuel Vapors
Since a sterndrive engine sits inside the boat, there's a risk of fuel leaks. Because of this, you need to use a bilge blower to remove any fuel vapors. This is important to prevent fires or explosions. Outboard engines don't need a blower because they are outside the boat. While the controlled explosion of fuel vapor inside the engine is what makes it run, you definitely don't want that kind of situation inside the boat itself.
Key Takeaways
- Sterndrive engines are heavy and take up a lot of space.
- They generally require more maintenance and repairs than outboards.
- You cannot trim a sterndrive completely out of the water, which can lead to more corrosion.
- Sterndrives may use more fuel due to their size and weight.
- A bilge blower is needed to manage fuel vapors inside the boat.
While sterndrive engines have benefits like a clean swim platform and a smoother ride in rough water, it's important to be aware of these potential issues before making a purchase. Knowing these things can help you decide if a sterndrive boat is the right choice for you.
