Hydrofoils and Hydrofoil Stabilizers: How These Technologies Help Boats

What Does A Hydrofoil Stabilizer Do?

When it comes to boating performance, there are plenty of ways to tweak your vessel to up its operation. For many, speed can be a concern, whether it's for recreational use or otherwise. And while plenty of different strategies exist to boost this stat potentially, hydrofoil stabilizers provide an exciting option to work with and install.

A wing-like structure, hydrofoil stabilizers serve to reduce the overall drag on boats when moving through the water. But how exactly do these add-ons work, and what are the benefits?

What Are Hydrofoils?

As mentioned, hydrofoils are structures, and they generally have wing-like shapes. Overall, they serve a similar purpose to aerofoils on planes: reducing the drag to help with speed and fuel efficiency. Typically, boats that have hydrofoils installed on them are also known as "hydrofoils." Both larger passenger vessels and smaller ships can have hydrofoils installed.

This strategy for enhancing speed got its start in the late 1860s and would later go through several different iterations and adjustments for both military and recreational use. Hydrofoils were most popular during the 1960s and 70s, but several larger passenger vessels today still use the technology, and it's possible to find personal watercraft with them or modify one for yourself.

Performance Aspects

Hydrofoils work to help a boat reduce drag and increase speed. Because water provides resistance to a ship trying to move through it, the resulting pushback can make a vessel slow down, even at peak operation. Hydrofoil stabilizers will redirect the water flow downward, reducing that resistance and helping the ship travel faster.

While speed tends to be the primary benefit of hydrofoils, fuel efficiency receives a boost as well. Since there is less force pushing on the boat, the engine doesn't need to work as hard to travel across the water, and thus it burns less gasoline in the process. While other factors can impact fuel efficiency, hydrofoil stabilizers are one aspect that can affect both it and speed.

How They Work

Hydrofoil stabilizers primarily come in two different shapes: U-shaped ("surface piercing") and more modern T-shaped ("fully submerged") models. While different in design, both types of hydrofoils work on the same scientific principles to help increase speed.

When looking at boats that have hydrofoils, you can see the wings attached to the bottom of the hull. Unlike regular ships, where the hull will rest in the water, the hydrofoils instead sit in the water, meaning that far less surface area comes into contact with waves. Because the hydrofoils are the primary contact point, there is less surface to encounter the water, resulting in less drag—and higher speed.

However, a hydrofoil will not always mean that the boat gets its benefits. The vessel must first reach a certain speed, which then allows the hydrofoil to produce enough lift to equal the boat's weight, which moves the hull out of the water, thus reducing the drag as described above. When this situation happens, the boat rides on the hydrofoils.

Types of Hydrofoils

U-shaped hydrofoils were some of the earliest models. Their "surface piercing" moniker comes from the fact that you can still see them along the sides of the hull even when the boat is in the water. These designs are still in use today, and they have the benefit of being much more self-stabilizing than the other potential option.

Even so, T-shaped hydrofoils have their benefits. The "fully submerged" refers to how the entire hydrofoil rests below the water, and this allows them to stay more stable against waves, generally allowing for a more comfortable ride for anyone on board.

Since they can't self-stabilize, though, it takes regular adjustments to make them work, usually handled by sensors and computers. For some configurations, rather than a straight pole down, the hydrofoil bends at an angle before reaching the "T" tip.

L-shaped hydrofoils are also coming into play, as seen by their use in recent years for the 2013 America's Cup, helping these vessels reach high speeds. Some of the newer systems of hydrofoils are retractable, which helps solve some of the inefficiency issues that can happen when not running at the appropriate rates to create lift.

How Much Use Do Hydrofoils See Today?

As mentioned, the 60s and the 70s were the most popular time for hydrofoils. They still exist today, but generally on smaller leisure boats and medium-sized passenger boats. You can also see them on some top quality sailboats. Very rarely will you find hydrofoils on any yacht. And while you can still find them, the cons of hydrofoils have prevented them from becoming more widespread:

  • They are complex to build and maintain, especially the adjustment systems required to help T-shaped hydrofoils stay balanced in the water.
  • Boats that use hydrofoils require potent engines, which can be expensive.
  • Hydrofoils have sharp edges, which not only create maintenance issues but are also possibly dangerous to wildlife and people who handle them.
  • Not suitable for shallow waters.
  • When the foils aren't creating lift, they actually create more drag on the boat, making the operation less efficient.

These negatives don't make it impossible for hydrofoils to work, but they're not the most economical option for manufacturers or boaters, either. Aside from boats, other watercraft will use occasionally hydrofoils, such as surfboards and electric bikes.

Hydrofoils and Hydrofoil Stabilizers

Since hydrofoils don't have as many benefits to balance out their cons, technology has given way to other ways to help balance out speed and fuel efficiency when it comes to boats. In a similar vein to hydrofoils, hydrofoil stabilizers are an add on to a boat's outboard motor that works to help vessels plane quicker and reach top-end speeds.

While that's the short version of the answer to "What does a hydrofoil stabilizer do?", it's essential to recognize that the benefits of stabilizers work best when there's an imbalance between the power output of the motor and the size of the boat.  This setup can lead to decreased fuel efficiency and porposing if the nose of the ship rises too high during acceleration.

Without the right matchup, you may not see any noticeable performance improvements on your boat. For smaller vessels, any minor improvements of hydrofoils may not be worth it. However, these stabilizers have the potential to significantly help out a larger boat if it's having issues, such as a subpar performance from used outboard motors. Those who don't feel like they're having troubles won't find hydrofoil stabilizers to be a worthwhile investment.

How Much Do Hydrofoil Stabilizers Cost?

As we've talked about, one of the significant disadvantages of larger hydrofoil systems is that the motors necessary to make them work can be expensive. Stabilizers, on the other hand, work as parts added onto your outboard motor, so they don't have as high of a cost to get one.

When shopping online, you can find bargain hydrofoil stabilizers for approximately thirty dollars, while more advanced top-end models can cost $150 or higher, depending on what model you choose to purchase. Cheaper models tend to rely on fin styles, while costlier ones have more parts and pieces to provide the necessary adjustments to your boat.

When shopping, you want to ensure that you've chosen a model suitable for your boat's engine type. Otherwise, you may end up with reduced performance due to a mismatch in performance and output. Sizing is also important, though it is possible to make adjustments during the installation process if you need to do so.

Installing Hydrofoil Stabilizers

For the most part, many stabilizer products require you to attach the hydrofoil directly to the outboard motor fin with included bolts. This process can go smoother if you have the correctly sized drill bits in advance to help create the holes to attach the stabilizer in place. Some manufacturers even make hydrofoils that simplify setup even more if you're worried about it.

If things go smoothly, you can attach the stabilizers in twenty minutes or so, but, like with many other boat projects, allow some extra time in your schedule just in case something happens to go wrong. Aside from matching with your engine, however, you don’t have to worry about the brand of your ship, from G3 Boats or otherwise.

Installing a hydrofoil stabilizer does not have any impact on your boating insurance policy.

Wrapping Up

In a perfect world, we wouldn't have to worry about engines not matching up with the size of the boat and causing issues. Unfortunately, it still happens, so something like hydrofoil stabilizers can help balance things back out to get better performance from your boat in terms of planning and fuel efficiency, so long as you have the right matchup.

Looking at larger-scale hydrofoils, you likely won't get your hands on them unless you go specifically looking for them, but the newer advents to the technology may change how we see them, especially with L-shaped, retractable models seen on sailboats and their use on other recreational watercraft. If you want a ship with this capability, a boat payment calculator can help determine the costs.

Whether or not they make a full comeback, we may find ourselves with more ways to enhance our vessel's speed, fuel efficiency, and overall performance.