How Do Pontoon Boats Float and What’s in the Tubes?

No doubt, the pontoon boat is perhaps the most curious looking watercraft of the bunch. With a flat deck resting on two (or three) tubes, this standout design can definitely get your curiosity going. And with such an outlandish look to it, you just might find yourself wondering - exactly how do pontoon boats float? Here’s a quick explainer.

The Pontoon Boat Design

There are lots of speculation as to how the pontoon boat floats. Some people have said that it’s because the tubes are filled with air, others even go as far as saying that they’re filled with nitrogen. But these interesting claims are nothing more than conjecture.

The simple explanation is that those tubes are hollow and completely sealed off, which means they don’t let any water get inside. On top of those tubes is a flat hull that rests on the tubes for support. In theory, a flat hull should be able to float on its own, kind of like a raft. But because pontoon boats carry heavy equipment like a console & cover, seats, and other additional fixtures and accessories, it needs more buoyancy to support its weight.

The solution then is to throw on some tubes. Essentially, these tubes improve buoyancy and keep the hull from submerging into water, which is also why pontoon boats tend to sit higher on the water’s surface than most other boats.

If you want to get into the science side of things, these pontoon logs resist the force of gravity a stronger buoyancy force. Had the boat gotten rid of the tubes with just the hull directly on the water’s surface, the force of gravity would push the boat underwater because its net buoyancy force wouldn’t be enough to keep it afloat.

Can a Pontoon Boat Sink?

On the topic of floating, you might actually find yourself wondering whether a pontoon boat might also sink. In theory, if you damage your tubes enough, it might be possible. But remember that pontoon boat logs are designed so that they aren’t easily sunk.

Each tube has chambers inside that are sealed off from one another. Should your tube be damaged, cracked, or punctured, these chambers prevent water from entering the entire tube. Now, unless you produce enough damage to fill both tubes entirely, then sinking your pontoon might be next to impossible.

Even then, filling up those tubes through nothing more than a crack would take quite some time. And even if you filled up a whole chamber, the rest of the tube plus the buoyancy of the opposite pontoon would still likely be enough to keep your hull from going under.

Check out our in depth answer to: can a pontoon boat sink?

A Quick Lesson in Buoyancy

Sure, a pontoon boat might not look like the typical boat design you might have in mind. But even then, it’s impressive structure means that it’s virtually unsinkable (in the right conditions and with the right care.) So, how do pontoon boats float? It’s really just a matter of the air filled tubes that give the pontoon it’s signature silhouette.