When it comes to making a boat move over the the surface of the water, you have a few basic options.
An engine, sail or oar.
If you plan to do any serious distance travel and/or you have a boat much larger than a dinghy, oars are probably not the best method of propulsion.
If you own and operate a Viking longship, allow me to respectful withdraw that statement in your specific case.
Sailing is a great pleasure, but also a lot of work and requires a lot of specialized knowledge and equipment.
Thus, most people who own a boat tend to own one that uses a fuel-powered motor. (Some boats are electric, sure, but most aren’t, so for our purposes today, assume that when I say motor or engine, I’m talking about a gas-powered system.)
So, then there were two, the inboard motor and the outboard motor.
Technically there’s an odd third option, the inboard/outboard motor, also known as a sterndrive. This is a sort of hybrid of the two, but we’re not going into depth on that one today.
Being a canoe owner and frequent paddler myself, let me state for the record that I often wish I had at least one option—an inboard or an outboard, e.g.—at my disposal, especially a few hours into the trip.
I suppose I’ll have to settle for a trolling motor like the Minn Kota Endure C2 and putter along at a couple knots if I want a break from the paddles. Trolling motors are a whole different thing, but they get the job done for small boats.
But if you’re considering buying a boat, you have other options. It’s time you ask yourself that timeless maritime question: Should you go with an inboard or outboard motor?
This is also what’s known as a “big decision.”
An Introduction to Inboard and Outboard Motors
Outboard Motor 101
In the broadest strokes—get it? Like four-stroke motor?—an outboard motor is a self-contained propulsion system wherein every aspect of the engine is built into the unit.
That includes the actual engine (often called the powerhead), a gearbox, brackets for mounting the unit, air intakes and exhaust ports, position adjusting hardware (see a note on “trim” below) and the actual propeller itself.
In most boats, save for very small craft used for fishing or for motoring around in harbors or smaller lakes, outboard motors are connected to controls at the helm, usually in the form of a steering wheel and a throttle, as well as an easy way to power off the motors as needed, especially in the event of an emergency.
Smaller outboard motors with two to four cylinders usually deliver less than 150 horsepower. Larger units can be rated at 500 horsepower and more. When several large outboard motors are working in concert, they can easily propel larger boats, even those easing forty feet or more, through the water at high speeds.
The Benefits of the Outboard Motor
- Easy to Remove — An outboard motor can be removed from a boat with relative ease, whether for repairs or replacement with a new unit, or when the boat goes into storage for the season.
- Safer in Shallow Waters — On most boats, outboard motors can be raised completely out of the water, thereby allowing the boat to safely enter very shallow areas or to dock water where the tide rises and falls significantly.
- Lower Cost — Generally speaking, most costs associated with outboard motors, from purchase to maintenance, are lower than those of an inboard boat propulsion system.
The Drawbacks of Outboard Motors
- Understand Trim — With outboard motors, trim is basically the tilt of the motor. It’s the angle at which the propeller is facing while pushing the boat along. A trimmed-out motor keeps the prow raised, a trimmed-in motor pushes it down.
Proper trim helps keep the boat in control and efficient. Improper trim can make the boat too slow, too non-responsive, and can even increase the likelihood of a serious issue like a capsizing.
- Propeller Danger — If you have ever seen a picture of a scarred Florida manatee, you know what horrible injuries a spinning propeller can inflict. Don’t ever let that happen to a human (or an animal, if you can avoid it).
- Remember to Raise It — Outboard motors stick farther down into the water than many boaters realize. When you approach shallows, raise the engine even if you’re not going to lift it fully out of the water. This is especially important when rocks are around.
Inboard Motor 101
As the name suggests, most aspects of an inboard motor are, well, inside the boat. The engine system is connected to one or more propellers that are outside the boat (or yacht or ship), but the actual motor, gears, cooling system and so forth are housed inside the boat.
In boats of a certain size, and that generally means larger vessels such as cabin cruisers or yachts, inboard motors are often the only option, FYI. And likewise for smaller boats, like my canoe, they might not be an option at all.
The Benefits of the Inboard Motor
- Power Play — Ultimately, an inboard motor can provide more power, which can equate to more speed and/or more capacity to move a larger boat. Inboard motors aren’t limited to housing attached to the back of the boat, thus they can be much larger than outboard motors.
- Minimal External Hardware — Inboard motors have minimal components outside the boat save for the propellers themselves. This allows for a sleeker profile, less chance of the propeller dragging on the bottom or over rocks without the need to raise the propeller, and allows for a deck at the back of the boat for swimmers, lounging or storing gear.
- Silence Is Golden — Okay, no inboard motor is silent, but they tend to be significantly quieter than outboard engines, especially when compared at higher speeds.
The Drawbacks of the Inboard Motor
- Dollars and Cents — Inboard motors are much more expensive than outboards when it comes to repairs or replacement. Just accessing the engine can be a laborious process and a costly one if you need to hire a professional.
- Space Requirements — Inboard motors, being houses within the boat’s hull, take up a lot of space that could otherwise be occupied by people, cabin room, or storage space for supplies.
Inboard and Outboard Motors: Which One Is Right for Your Boat?
If you’ll forgive my impertinence, there’s a chance you’re asking yourself the wrong question here.
Your first concern should not be whether inboard motors or outboard motors are better or worse. Rather, you should be thinking about what type of boat you have and/or want and what you’ll use your marine propulsion system for.
Outboard motors tend to offer tighter turns and a more athletic response, so if you’re thinking about a smaller speedboat that will be enjoyed for its namesake—that’s speed, I mean—then a setup with an outboard motor or two or three is probably your best bet.
If you have a larger cabin cruiser, you probably need an inboard system. And you’ll be glad for its smooth, steady, rather quiet operation during those multi-day trips out on the water.
If you use a midsize pontoon boat like, say, a SunCatcher V22RF, then there’s not really any place for an inboard motor to go, now is there? So hey, good thing that outboard and inboard motors exist, right?