Why Do Pontoon Boats Sink?


sinking pontoon boat

Pontoon boats are fantastic recreational vessels that offer a sense of style and luxury for cruising and fishing on inland waters. They are very stable and safe boats when used in the right way, in the correct environment and under the appropriate conditions. So why do these majestic boats sometimes sink?

Pontoon boats can sink for a number of reasons. The most common reason for a pontoon boat sinking is overloading. Poor weight distribution, using the wrong motors, having water in the pontoons, inappropriate handling of the vessel especially in waves and chop, and using the boat in the type of very harsh conditions it was not designed to be used in, are all things that can cause a pontoon boat to sink.

Why do pontoon boats sink?

Pontoon boats are usually pretty stable vessels and they will be very safe to use if they are handled correctly, if you follow the manufacturer’s guidelines and if you maintain a healthy respect for both the water and mother nature.

When pontoon boats sink it is always down to human error. Sinking can, and should, be prevented. Of course if another boat hits your pontoon and there was no way you could avoid the collision that is a completely different matter (though still down to human error).

In this article I will address the main reasons a pontoon boat sinks when it is not hit by another vessel.

Overloading

Loading a pontoon boat to the point where it is over capacity is not a smart thing to do. Overloading is the biggest cause for pontoon boats sinking.

The problem with overloaded pontoon boats is that they tend to look fine even when they are well over their weight capacity. Because a pontoon boat deck is large and spacious people tend to load more stuff on it, including passengers, than is safe to do.

Even if a pontoon boat were so heavy that the pontoons/tubes were very low in the water the boat would still appear to be floating in a stable position. However, when you start the boat and attempt to move off it will quickly become apparent that the pontoon is going to sink.

To avoid overloading always follow the weight capacity guidelines of the pontoon boat’s manufacturer to ensure your load is well within the boat’s weight limits.

Taking look at the water line against the pontoons is a great quick way to determine if your boat is overloaded. The water line should never be above the middle of the pontoons. In fact, the lower the water line is, the better.

You should also note that the water line at the bow end of the pontoons should be lower than the water line at the stern end. When the water line at the front of your pontoons is lower than the water line at the back of them this means your boat is heavier at the back than the front. This is how it should be on a pontoon boat.

As you will see later, if a pontoon boat is not lighter at the front than the back it can lead to the boat taking a nose dive into the water.

Poor weight distribution

Not distributing the weight correctly on a pontoon boat can lead to the boat sinking, especially if the water is choppy.

As mentioned above, it is important that a pontoon boat is lighter in the bow area than at the stern.

When too much weight is placed at the bow of the boat the pontoons at the front of the boat  are forced lower into the water. This causes a “ploughing” effect to occur when the boat is throttled up. The boat literally starts ploughing through the water instead planing above it.

When a pontoon boat “ploughs” through the water it will eventually start to take on water at the front end and will sink front first.

Wrong motor types mounted

The HP of the motors on a pontoon boat are very important and must fall between the minimum and maximum power levels for that boat.

A motor that does not have enough HP to power a pontoon boat will be unable to lift the front of the boat out of the water sufficiently for the boat to get on plane. When that happens the ploughing effect mentioned above starts to occur.

Water in the pontoons

The tubes that a pontoon boat sits on are called pontoons. They are hollow tubes that give the boat buoyancy and keep it afloat on top of the water. These tubes have a tendency to take on water over time because they are hallow.

If there is water in the pontoons then the boat will sit lower in the water and thus be unable to get on plane. This also leads to the ploughing effect mentioned previously.

To avoid problems with the pontoons regular draining of the tubes is needed to maintain a safe boat. Pontoons are fitted with drain plugs that merely require you to unscrew them and let the water pour out before screwing the plug back in.

Some pontoons are chambered though and this can cause problems when trying to drain the tubes. When a pontoon is chambered it means the tube is sectioned into different parts.

Why is this a problem?

Well, there may be water in one chamber and none in the others. If the drain plug does not empty all the chambers you may find it difficult to get all the water out of the pontoon.

So draining chambered pontoons requires a different approach as outlined here.

Incorrect handling

A pontoon boat is fairly easy to drive and offers a good bit of acceleration as many boats are capable of reaching speeds up to 25 mph, but that doesn’t mean you can drive one like it’s a speedboat.

Many people sink pontoon boats because they try to take waves and wakes too fast and without proper caution.

Pontoon boats require special handling especially when it comes to waves and the wake of larger vessels.

When you encounter the wake of a larger vessel you must slow down. With reduced speed you should then take the wake at roughly a 45 degree angle. Work the throttle so that you can lift the bow up on the initial wave, and keep it up on any subsequent waves that follow.

Trying to speed through waves and wake will cause your boat to take on water and it may lead to it sinking. Always slow down near wakes and on choppy water.

Using the boat in very harsh conditions

A pontoon boat is a recreational boat. It is designed for fun days in the sun. It is not a utility boat nor is it a deep draft boat designed for turbulent water.

As a shallow draft vessel a pontoon boat performs best in calm shallow waters. It will struggle in rough water.

Never use a pontoon boat in very bad weather conditions or in very challenging waters. Although pontoon boats can be used in the ocean, they can only be used under very specific conditions and only close to the shore.

How to stop a pontoon boat taking a nose dive

Most pontoon boats that sink, sink front first. This is known as a nose dive.

We have covered the subject of why pontoon boats nose dive and how to prevent it in the article why did my pontoon boat nose dive.

That article also has an easy-to-implement simple trick to completely eliminate the change of your pontoon boat nose diving, regardless of the conditions.

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