Boats handle best when they run parallel with their at-rest waterline — you’ll notice a more comfortable ride, increased speed and more efficient gas mileage. The bow of your boat meets the water at a specific angle — and that angle has a direct correlation to how efficiently you operate your vessel.
Trim isn’t something you can set and forget because load and water conditions change regularly, so having the ability to adjust it on the fly is essential. It’s equally as important to know how to fix it properly — failure to adjust it incorrectly could cause the boat to swamp. If you tilt the angle of the engine too far in or down, known as negative trim, the bow of your boat will drop. If you tilt the angle of the engine too far out or up, known as positive trim, the bow of your boat will rise.
To give boaters the ability to adjust and maintain the proper angle, outboard and sterndrives feature a power trim adjustment that gives you the ability to tilt the drives’ angle out or in. However, this means the propeller handles the power trim, which was designed to force the boat in a forward motion. When the prop is used for trim, the prop is pushing the boat forward in addition to raising and lowering the stern — this increases the prop slip, killing your boat’s performance. The power trim adjustment is also ineffective at slower speeds and unable to correct listing.
In addition to increasing prop slip, the power trim adjustment is solely for adjustments on the axis that runs fore — closer to the bow, or front of the boat — and aft — closer to the stern, or back of the boat. In other words, power trim adjustment only helps you make adjustments to the angle of your boat tilting more forward or backward. What happens when you need to correct a leaning problem, known as a list? The simplest answer is to redistribute the weight of passengers and cargo to compensate for the sideways list, but conditions are always changing, and redistributing weight at higher speeds can have a magnified effect on the shift of the boat.
To maximize the control of your trim and address both of these issues — avoiding prop slip and making lateral adjustments — adding trim tabs to the transom is ideal.
Trim tabs are two independently adjustable metal plates controlled by a panel at the helm. These tabs can help compensate for engine torque or unequal weight distribution. What do trim tabs do on a boat? They give you the ability to trim the hull and the prop independently and to make lateral adjustments to avoid sideways list. Since the trim tabs can take over trimming the hull, the power trim can focus solely on adjusting the prop. By having the power trim and trim tabs work together, your boat achieves optimum performance and efficiency you can’t get with the power trim alone.
Now you understand what trim tabs do on a boat — but how do they do it? These tabs are mounted on either side of the transom of the boat. They are completely independent of one another — not connected to each other. When you’re focused on adjusting the power trim of the boat, you now have two additional metal plates you can use to do the heavy lifting when it comes to tilting the engine in or out. In this case, you’d have both metal plates tilted about the same angle in or out, to match the power trim of the engine. This alleviates some of the work on the prop and helps you maximize performance.
But what happens when you start to notice the boat leaning? Without trim tabs, there isn’t much you can do besides moving passengers and cargo or adjusting your speed and route. Fortunately, you can adjust each of the trim tabs independently and can easily compensate for a shift in sea conditions, weather, etc., without having to make adjustments in weight distribution or changing your route.
Now you know what trim tabs do on a boat and how they do it, you may be wondering what trim tabs you need. There is no one-size-fits-all solution for trim tabs. The size of the tab you need depends on several factors, including the engine, weight of the boat, length of the boat, weight distribution and type of boat, among other things.
Whether you’re just getting started with learning power trim adjustments, or wondering how to use trim tabs in rough water, we’ve gathered some valuable tips for using your boat’s trim. We’re sure these will come in handy as you begin searching for your boat’s perfect trim — regardless whether you’re boating in a lake or on the ocean. It’s important to remember each boat’s trim is different, so for every boat, factors such as the balance of trim, weight of the boat, sea conditions, speed, etc., are a little different. While these are general tips, it’s important to always operate your boat with caution as you begin discovering your boat’s ideal trim.
If you’ve been wondering how to use trim tabs in rough water, you’re not alone — in fact, regardless of whether you have trim tabs, you must consider sea conditions, since they directly impact how you find your boat’s perfect attitude. Therefore, your boat’s attitude should change depending on what type of sea you encounter. Be mindful, small adjustments can have a big impact — in both power trim and trim tab adjustments, but also adjustments in weight shifting on the boat. Just because you’ve changed your boat’s attitude to match sea conditions doesn’t mean you can set it and forget it on the water. Passengers moving on the boat and changing sea conditions are two reasons finding your boat’s perfect attitude can be a permanent work in progress.
Here are some adjustments you should consider making to improve your boat’s attitude in each of the following sea conditions.
Mastering your boat’s trim so you can use it to your advantage isn’t easy — it takes the right set of tools, knowledge and patience.
At Formula Boats, we’ve been a boat manufacturer and dealer for more than 60 years, so we understand how boats, engines and trim tabs can work together to maximize your performance to give you increased speed, a smoother ride and improved fuel efficiency.
If you have questions about perfecting your boat’s trim — or aren’t sure where to start — please don’t hesitate to contact us.