Unsinkable Boat: What Boats are Unsinkable?

Unsinkable Boat

There are few things that can fill a boater with dread, like seeing water rush into the hull. Impact with debris or the ocean bottom can be disastrous in an old-fashioned boat, but with an unsinkable boat, it will only be an inconvenience. 

What boats are unsinkable?

Everglades 255cc Center Console

By Coast Guard and Congress law, just about any boat under 20 feet long designed for ocean use is unsinkable. Companies like Boston Whaler, Edgewater, and Everglades are also making unsinkable boats up to 37 ft long.

Here’s what you need to know about what makes a boat unsinkable, why it’s so hard to find a larger vessel that is unsinkable and some makers of quality unsinkable boats.

Unsinkable Boats Under 20 Feet Are Required By Law

Boats under 20 feet long are mandated to be unsinkable by law. The Coast Guard and Congress mandate flotation standards since these boats may be so much more likely to sink down to the depths relatively easily. 

Before these mandates, a boat that punched a hole through its bottom or burst a pipe onboard could sink incredibly quickly. In the 1970s, these mandates were put into place and have probably saved many thousands of lives.

As time has gone on, more and more boat enthusiasts are demanding unsinkable boats. At the same time, technology continues to advance to make building unsinkable boats easier. Therefore, there is now a great collection of unsinkable motorboats for you to choose from. 

Unsinkable boats are especially essential for the beginner. Getting in a motorboat for the first time can be intimidating enough without worrying about it sinking on you. 

Knowing that a boat will maintain floatation even if it capsizes, gets a hole, or has a flood can put the beginner’s mind at rest and make them more likely to make a purchase.

Since beginners usually start with smaller boats, the market has been motivated to compete to create unsinkable power boats beneath 30 feet. Any boat this size that isn’t unsinkable is much less likely to attract attention from beginners.

Another demographic to which unsinkable boats matter is the experienced fisherman who has had bad experiences in the past. Offshore fishermen who have had a frightening experience with a sinking boat are more likely to invest in an unsinkable boat next time.

Are Unsinkable Motorboats Really Unsinkable?

There is certainly some variation in the market when it comes to unsinkable motorboats. Motorboats with hulls filled with air are much less unsinkable than those with foam, since air pockets can be punctured and filled with seawater unlike foam.

The best unsinkable boats, those with a very sturdy and extremely buoyant foam lining, are truly as close to unsinkable as you could imagine.

For instance, on the Unsinkable Legend Tour, an 18-foot Boston Whaler was cut in half and launched in various locations all over the country to show off just how unsinkable it really is.

Unsinkable Boat Brands

Here are some of the most unsinkable motorboats and how they construct their highly durable hulls.

Boston Whaler Boats

The Boston Whaler is the most famous unsinkable boat for good reason.

This company launched the unsinkable boat craze many years ago, and they have continued developing extremely buoyant boats of various sizes and makes ever since. 

They use their own technology, known as UniBond, to sandwich foam between fiberglass.

The hull and deck are joined together, and before the resin even cures, liquid foam is injected, causing a chemical reaction that bonds the glass and foam together.

This creates a nearly perfectly cohesive unit, with the fiberglass and foam sandwich providing structure and buoyancy no matter how the hull is cut or punctured.


This is another company that has taken advantage of modern advances in computer technology to create a wonderfully buoyant boat. They use a pre-formed foam that bonds to the fiberglass in the hull. 

This structure is then wrapped in fiberglass, and most of the area below the deck is filled with foam. On boats that are longer than 20 feet, additional foam is provided in order to keep the boat stable even if it fills up with water.

The Edgewater is now making a 37 ft unsinkable powerboat, one of the largest unsinkable powerboats available.


Everglades creates a practically one-piece hull using their patented process.

Pre-molded foam cores are created in the shape of the hull, the deck, and the transom.

Then the hull and deck are laid over them, and the entire thing is vacuumed and sealed to create an extremely tight molded core. 

Everglades 255cc Center Console
Everglades 255cc | Photo Source

According to the makers, this technique gives them a lot of control over the foam core quality and superb durability so that this boat will stand up even if it is put through extreme wear.

This treatment is available on all Everglade boats up to 24 ft long.

Why Aren’t Larger Boats Built To Be Unsinkable?

When you consider the tremendous safety advantages and peace of mind of an unsinkable boat, you may wonder why this capacity isn’t available in much larger boats.

As technology advances, we are seeing unsinkable boats come out in larger and larger sizes, but it still has not advanced to hardly any boats more than about 30 ft long. Here are a few of the reasons that larger boats typically are not unsinkable:

Difficulty In Construction

It’s not easy to fill a boat with foam to create buoyancy. The more space that needs to be filled, the harder it is to do it in the necessary time frame before all of the components have dried and set.

The boat must sit in the mold for some time, which slows manufacturing, especially with the amount of room larger boats would take up.


Boats larger than 30 feet are much more likely to be used for liveaboard and extended trips, unlike boats that are under 30 feet, which are more commonly used as day cruisers. That means that larger boats need more space for storage. 

The foam takes up a lot of room. In fact, it may take as much as 6 or 7 cubic feet of foam to fill a boat that’s about 35 ft long. That’s an awful lot of room to take up in a boat that could otherwise be used for living space or storage.


These boats cost more because of construction difficulties and the specialized skills often needed to make a boat unsinkable.

Consumers can typically afford the additional cost in boats under 30 feet, but when this additional cost is added to boats more than 30 ft, it may become harder to sell an unsinkable boat.

Makers considering the cost-benefit analysis often decide that it is not worth investing in boats over 30 feet that are unsinkable. 

Larger Unsinkable Boats?

Demand is growing for larger unsinkable boats, and the boat-building company ETAP was taking steps to meet that growing demand. This company built its unsinkable boats with a typical outer hull that would be sufficient by itself, although not unsinkable. 

This hull is then fitted with an inner hull and bonded to the outer hull. Foam is injected into spaces between the two hulls. Not only does this foam keep the boat buoyant, but it channels water to keep the boat level. 

ETAP was already using this technique on boats as long as 37 feet, but they were planning to extend this technology to boats as big as 46 feet. Unfortunately, the company went under, and their larger unsinkable boats never went to market. 

While working boats and occasional cruising boats can be found up to 40 feet long, you’ll be hard-pressed to find an unsinkable boat much bigger than 30 ft.

It is even harder to find unsinkable motorboats since unsinkable sailboats seem to be a more common need.  One of the largest unsinkable boats currently available is the 370cc by Edgewater, which is built with single-piece infusion. 

Safest Boats For Long-term Cruising: Smaller Unsinkable Boat Or A Larger Boat?

Suppose you want to live aboard your boat or take it out for extensive journeys. In that case, you will have a difficult decision to make as to whether you want to go larger and sacrifice the unsinkable quality or stick to a smaller unsinkable boat. 

Where you intend to spend your evenings may help you to decide what kind of boat you want. If you are going to the marina most nights, you probably won’t have trouble stocking up on new supplies every day, and you’ll have the opportunity to stretch your legs. 

Therefore, you will likely be able to get away with a smaller boat and still be very comfortable living aboard. Furthermore, you’ll pay less for slip space with a smaller boat.

On the other hand, if you are anchoring out, you want all the supplies that you need for your trip at the beginning, so you’ll need more room for storage.

Another important consideration is what you want to do with the boat. If you enjoy fishing in deep water, but do not go very far offshore, having an unsinkable boat probably won’t be as important to you as if you are frequently traveling in shallower water where you may hit the bottom or if you are out in the deep ocean where a sudden storm may capsize you.

Enjoy The Peace Of Mind Of An Unsinkable Boat

An unsinkable boat can put your mind at ease, whether you are a beginner or an experienced sailor.

Knowing that if you hit the bottom or capsize, you will not be left treading water can make the difference between feeling confident in the ocean and motoring with anxiety. 

That said, always come prepared with a life raft, flotation bags, bilge pumps, and the ability to make a distress signal just in case your cockpit floods and you and your crew wind up needing help.