Handling Obstacles: Logs and Hydrofoil Boats

Hydrofoil boats, marvels of modern engineering, glide above the water surface at high speeds with minimal drag. Yet, their interaction with floating debris like logs and branches is of primary concern. While conventional boats often face significant damage from such impacts, hydrofoil vessels employ advanced safety systems to mitigate these risks.

Boaters in areas such as the Pacific Northwest often confront the challenge of navigating around floating logs, especially after storms or king tides. To safely traverse waters with potential log hazards, mariners typically:

• Reduce speed
• Remain vigilant
• Steer clear of known accumulation zones
• Avoid areas with whirlpools containing logs, especially during slack periods

Following these practices could significantly reduce risks.

Foil boats, are a step ahead of regular boat designs. They have robust hydrofoils, built to withstand impacts from submerged objects, including logs.

Hydrofoil craft, by design, lift their hulls out of the water, reducing drag and increasing speed and efficiency. Nonetheless, this implies that the submerged foils, which provide the lift, could be susceptible to collisions with both underwater and floating debris.

Here are some common issues and solutions associated with hydrofoil boat collisions:

• Operating with their foils submerged below the water’s surface, hydrofoils are prone to hitting objects floating just beneath the surface, such as logs and submerged debris.
• Collisions of these objects with the fully submerged foils can inflict significant damage on the boat’s structure and impair its functionality.
• Traditional hydrofoil designs might struggle to withstand impacts from large objects. This necessitates the development of stronger materials and innovative designs that can absorb and mitigate the impact forces.

To address these challenges, modern foil boats incorporate the following features:

Shear-off points:

The design of shear-off points makes them break away upon impact, preserving the integrity of the main vessel.

Advanced collision-avoidance systems:

Utilizing sensors and AI, these systems detect and evade obstacles, thus enhancing the boat’s safety under various operating conditions.

Reinforced titanium alloy and carbon fiber foils:

Titanium alloy and carbon fiber foils not only ensure a lightweight structure but also provide excellent impact resistance against submerged objects.

Retractable foil systems:

When navigating areas with a high likelihood of debris, the foils can be retracted to avoid impacts, similar to the mechanism seen in Candela vessels. This feature allows the boat to operate efficiently in rivers and lakes with varying water conditions.

These innovations in hydrofoil technology contribute to the safety, performance, and smoother ride of modern hydrofoil vessels.

Candela has devised sophisticated collision-avoidance systems for its P-12 and C-8 vessels, blending real-time computer adjustments with structural design to counteract the risks associated with encountering debris.

Candela’s vessels are engineered with foil struts that can withstand impacts from various sized objects.

One of the most common questions we get is how a hydrofoil vessel copes with floating debris such as logs, branches, trash, or other objects floating in the water. In fact, our foiling boats can handle debris with active and passive safety systems. Therefore, if they hit something, they provide a level of safety that conventional boats don’t.

Longevity and robustness are embedded in the design of our P-12 and C-8 vessels. The foils can be retracted in shallower waters with the push of a button. As a result, the C-8 to access water depths as little as 60 cm and the P-12 less than 1 meter draft – minimizing the risk of running aground.

Floating objects do not hit the actual fully submerged foils, which during foiling are up to 2 meters below the surface, but instead bounce off the sturdy struts made from solid carbon fiber.

The foil struts on the Candela C-8 and C-7 have withstood hits from wooden pallets and branches without damage – just producing a bang and then causing a gentle touch down and landing. The Candela P-12 ferry is a bigger vessel, with much larger struts, and can hit even bigger objects without sustaining damage. It can also handle impacts from logs, which is one of the main concerns for operators on rivers and lakes.

The P-12, C-8, and C-7 are also designed with built-in shear-off points on the foil system. In the unlikely scenario the vessel runs aground or into, a large underwater boulder, the struts and foil will break off in order to not damage the hull. Moreover, in case of a major impact, The P-12’s motors are designed to swing back and upwards, just like conventional outboards. That’s why, a Candela vessel has a very high probability of staying afloat in a major collision with an underwater obstacle, whereas a conventional vessel with a traditional hull might sustain hull damage and sink.

We’re exploring an advanced collision-avoidance system, which detects objects and persons, and assists the captain as an extra, watchful lookout, especially during high speed navigation. Consequently, it provides an additional layer of situational awareness, offering detection both on and above the water surface. This system analyzes various materials, including:

• wood
• steel
• plastic
• organic matter

It uses a neural network that performs segmentation, classification, and detection.

The system’s visual range extends to the horizon. However, the exact detection range depends on factors such as the size of the object and weather conditions. Additionally, it can differentiate between various entities, including:

• buoys
• persons overboard
• sailing or motorboats
• ships

Collisions with floating debris pose certain challenges to foiling boats. Yet, design and technological advancements, evident in Candela’s P-12 and C-8 vessels, provide robust solutions to these problems. For instance, by combining passive safety features with active safety systems, modern hydrofoil boats can handle the dangers of floating debris, ensuring a safer and more efficient operation.

You can read more about these boats and their different features in our comprehensive blog post:

Foiling vs. Floating; Understanding the Differences Between Hydrofoil Boats and Other Boats.

How do hydrofoil craft handle collisions with floating debris like logs? 

Several safety features are incorporated into the design of these boats to handle collisions. For example, Candela vessels have robust struts made of solid carbon fiber that can withstand impacts from objects such as wooden pallets and branches. Additionally, the foil struts are positioned to deflect debris away from the submerged foils.

What passive safety features do Candela vessels offer? 

Candela vessels offer the following passive safety features:

• Retractable foils, which enable them to navigate shallow waters
• Shear-off points on the foil system to prevent hull damage in case of major impacts
• Motors that swing back and upwards to avoid damage

What active safety systems are implemented in Candela vessels? 

Candela is exploring advanced collision-avoidance systems, employing sensors and neural networks to detect objects and persons. Moreover, this system enhances situational awareness by analyzing various materials and providing real-time alerts to the captain.

Can a foil boat operate in shallow waters? 

Yes, foil boats such as the Candela C-8, with their retractable foils, can navigate in shallow waters. The C-8 can access depths as meager as 60 cm, and the P-12, less than 1 meter draft.

How do hydrofoil boats ensure safety in the event of a collision with a large underwater obstacle? 

In the unlikely occurrence of a collision with a large underwater obstacle, the foils and struts break off at designated shear-off points, thereby safeguarding the hull from damage. Additionally, the motors are designed to swing back and upwards to avoid significant damage.

How does a hydrofoil boat maintain stability after a collision with debris?

A hydrofoil boat maintains stability after a collision with debris by using robust struts, retractable foils, and shear-off points. These features absorb and deflect the impact, thereby preventing major damage to the vessel and keeping it afloat.

What’s the difference between passive and active safety in hydrofoil boats?

Passive safety focuses on built-in structural defenses against collisions, while active safety involves technological systems like sensors and AI to detect and avoid obstacles in real-time. Active safety relies on technology, while passive safety is based on the boat’s structural design.

Can hydrofoil vessels safely operate at night or in poor visibility conditions?

Yes, they can safely operate at night or in poor visibility conditions, just like any boat. With advanced collision-avoidance systems that enhance the captain’s situational awareness, risks are further mitigated.

How do retractable foils contribute to the safety of hydrofoil boats?

Retractable foils improve their safety by minimizing the risk of collisions in shallow waters and near the shore, and by allowing the boat to avoid debris and rocks.

What happens if a hydrofoil boat encounters a large obstacle, like a submerged rock?

In such events, the boat’s shear-off points allow parts of the foil system to break away. This protects the hull and potentially prevents the boat from sinking. Motors designed to swing back and upwards help avoid further damage.