If you love to fish or just enjoy a bit of lake time, an aluminum boat is a great choice. Lightweight, easy to maintain, and also highly customizable, they’re a perfect choice of watercraft. They’re tough enough to venture offshore, and due to their lack of weight can carry a lot of payload for their size.
If you’re thinking of getting yourself an aluminum boat, there is a big question that you’re going to need to answer. It’s not going to go anywhere on its own, and unless you intend on rowing your boat everywhere you’re going to need an engine!
After all, aluminum boats make for fantastic small speed-craft. But what size motor do you need? This guide is here to help you out.
We’ll take a little look at the various things that can impact your choice of motor, from the use you intend for your boat and the sorts of loads you’re likely to be hauling to what top speed you’re looking for. By the time you’ve finished reading this, you’ll be ready to get that motor and get out on the water!
Rules And Regulations
Before we dive into the options available, just a quick reminder of the fact that Federal regulations exist governing the maximum horsepower you can install on any watercraft.
When you buy a boat the manual should include this information and any boat under 20 feet in length is required by law to have a capacity plate in the helm area that tells you what your maximum allowable horsepower is.
If for whatever reason your boat is missing this information, contact the manufacturer before you start looking at motors.
What Are You Using Your Boat For?
Aluminum boats are popular for island-hopping and general water activities, and also make brilliant fishing platforms. They’re a great way to get your hands on a relatively high-speed craft for a good price and are also useful for moving gear around between closely connected locations. The question for you is, what is your priority?
If you’re mainly getting out alone to fish, you’re not going to want to be adding a huge, powerful motor to your aluminum boat. For one thing, it’s not necessary to have that much horsepower at your disposal.
For another, more horsepower means a bigger, heavier engine, and if it’s just you and your catch in the boat you could end up with a serious lack of balance which could endanger you and your boat. You’re better off looking for something reliable and lower-powered.
If you’re using your aluminum boat for group outings or carrying more cargo, then you have a couple of options. It’s an obvious statement that a bigger, more powerful engine will consume more fuel; power and fuel consumption are directly related, with the caveat that different engines are more or less efficient than each other.
As a consequence, think about how fast you need to be getting your payload from one place to another. If you’re not prizing speed over efficiency, again look toward the lower-powered end. If you want to be able to move people and things quicker, then you can explore the higher end of the range.
It’s not just what you’re doing but where you’re going to be doing it that matters. Taking a group of friends for a trip across a mirror-smooth lake is one thing, but take those same pals out into choppier waters and your boat needs a whole different set of capabilities.
Rough water requires more horsepower to navigate than smooth due to the demands of meeting waves and wind. If you’re heading to the open seas, get yourself a bigger motor to cope with the conditions.
As alluded to in the last section, fuel efficiency is very important in choosing a motor. There are a few things to consider in this calculation. If you use your boat a lot as a major part of your lifestyle, it may be worth it to you to have a more powerful engine that burns more fuel.
However, frequent use can also mean that a thirstier engine is less attractive as it will cost you more over time. No guide in the world can work that particular conundrum out for you, as it very much depends on your personal circumstances and how much you are willing to spend on your boat! Either option is entirely valid.
Another thing to consider is how far you’re going to be traveling between opportunities to fuel up. If you’re doing short hops, then you may not find a less fuel-efficient engine to be a problem, as you can plan to refuel as you go.
If you’re intending to travel longer distances between landings and you don’t want to be constrained by the amount of fuel you need to bring with you then much like the tortoise and the hare, slow and steady may well win the race.
To add to this, your desired speed is important too. You don’t want to be running whatever motor you choose at the top end of its throttle range all the time to achieve your chosen speed, because you’ll be burning more fuel than if you had bought a more powerful engine and used it within its more efficient range.
Almost everyone makes decisions based on economy and fuel efficiency is the most important part of that choice over the lifespan of your boat.
Of course, your primary motivating factor might be speed. This applies across all of the use cases discussed above, and in deciding on your motor you’re going to need some benchmarks.
A good starting point is a 60-horsepower engine, which will give your lightly laden boat (i.e. carrying you and one other person) a top speed of around 25-30 mph. If you add more weight to the boat this speed drops, and running your 60-horsepower engine at wide-open throttle like this is not the route to the best fuel efficiency!
If you’re looking for that sort of speed regularly, then you’re going to need a more powerful engine. For example, a 90-horsepower engine in the same 16-foot boat with the same load will have a top speed of around 40 mph but will achieve around 25 mph in its most fuel-efficient throttle range.
That will result in a big saving in fuel over time, while also providing you with a bit more get-up-and-go from your motor.
When you’re looking at motors for your boat, the ticket price is going to be high on your list of considerations. While everyone has a budget and spending the big bucks isn’t a necessity, the motor for your boat is one component that will hold its value well over time.
If you can afford to lay out a little more for a motor, you will be able to shop around for the most efficient and powerful engine for your needs. You can also be confident that, if or when you come to selling your boat or upgrading the motor, you will be able to recoup a significant amount of your investment.
So there you have it; a broad look at the different reasons for choosing different-sized boat motors and a rough benchmark for what size of motor is capable of what performance.
The difficult thing with choosing something like a boat motor is that there is a whole heap of variables that apply to every purchase. It’s not as simple as just saying that your boat is 16 feet long and therefore you should get this specific motor.
Only you know what you want to use your boat for, how often you want to do so, what fuel economy you’re shooting for, and what budget you have.
It’s not just your individual circumstances that muddy the waters on this decision, but even simply the physical size of your boat makes a difference! If you’re intending on getting in at the higher end of the power spectrum, then you need to be careful to watch the regulatory maximum horsepower limit.
This isn’t the same for all 16-foot boats, as it is dependent on transom width. The build of your boat also has an impact at lower horsepower as well, because a broader-built hull approaches the water differently compared to a narrow one.
To achieve the performance you are seeking you may have to get a more powerful motor, or perhaps you will be able to get by with a less beefy option.
The key is to be guided by your manufacturer’s guidelines as stated in the manual and capacity plate for your vessel, your budget, and your desired outcome. Don’t forget that your local boating community is a haven of knowledge and insight too, and there will be someone out there to talk these issues through with.
If you come into any conversation about buying a motor forearmed with these thoughts that we’ve stepped through in this article you’ll find the process to be much smoother, and you’ll be out on the water in no time!