28. April 2022, updated 22. April 2024

Thundercat: The Most Fun For Your Money

a man and a woman together in a thundercat racing boat, jumping over a wave
Source: Aquarius Inflatables.

Come on, admit it, you’ve probably already fantasized how it would feel to ride on the water at over 50 knots. Well, such speeds reach only very few boats and those that do often are big vessels with high-horsepower engines and are therefore quite expensive. But there is one exception: the catamaran-style inflatable boats, known as Thundercats, Zapcats, or Pencil Ducks. With an empty weight to power ratio of about 3 kg/hp, such an inflatable boat is on par with a Porsche 911 Turbo Coupé (that’s only with the standard configuration of 50 hp!). Yes, it’s true that comparing a boat to a car sounds strange, but in this comparison, it becomes clear what incredible powerful boats we’re talking about. Is your heart already beating faster now? Then learn more about these impressive powerboats in this article!

Different Terminology

As mentioned at the beginning, various terms are in use for the catamaran-like inflatable boats: Thundercat, Zapcat and Pencil Duck. Thundercat and Pencil Duck are generic terms for this type of boat, although Pencil Duck is rather seldom used. Zapcat, on the other hand, is a brand name used by the South African manufacturer Gemini, and thus strictly speaking refers only to Thundercats from that one manufacturer. However, many people use Zapcat as a synonym for Thundercats/Pencil Ducks, although this is not correct.

History of Origins

The origin of Thundercats can be traced back to the coast of South Africa, where in the 1980s a somewhat crazy person started mounting a very powerful outboard motor on a rather small inflatable boat and then having the fun of a lifetime in the surf. A little later, an inflatable boat was developed to meet the requirements of high motorization and the rough water conditions in the surf on the coast of South Africa – the Thundercat was born. This type of boating quickly gained popularity around the coast of South Africa and organized races began to be held. Later, people around the globe followed enjoying such racing events, especially in Australia, New Zealand, and Great Britain. However, the Thundercat also gained popularity for recreational activities beyond racing.

The Design

Basically, Thundercats are a special type of Soft Inflatable Boats (SIBs), but the fundamental feature is that Thundercats have two speed tubes (also known as hijackers) under the main tubes. The collapsible bottom of the boat is usually made of wooden, aluminum or even carbon plates. At the bow, the two main tubes are connected with a nose cone, which is either made of GRP or carbon. Another special feature is that no conventional, closed transom is installed, but an open “wash through transom”, usually made of aluminum.

The classic dimensions of a Thundercat are 400 to 440 mm in length and 200 to 230 mm in width. The usual empty weight of such a boat is less than 85 kg and the standard engine (for racing) is 50 hp, although there are also some who motorize their Thundercat with up to 75 hp. For the engines, almost exclusively the light 2 stroke short shaft engines are used in the basic configuration with hand start and tiller produced by Yamaha or Tohatsu. The standard tiller is often modified by lengthening it and/or adding shock absorbers to improve control even in tough conditions.

There is little space inside the boats, but the boats are primarily intended for two passengers only, the driver and the co-driver. For the fuel tank, an ordinary mobile one made of plastic is used, which is then usually attached to the floor at the aft near the transom. But here, in favor of weight distribution, the exact position of the tank can be varied. In addition, the boats are equipped with holding straps on the tubes and on the floor, which allow the crew to find a hold on the boat even at high speeds.

In the figure below you can see quite well the layout of a Thundercat.

Advantages and Disadvantages

Now that we all know what a Thundercat is and how it is constructed, let’s take a look at the concrete advantages and disadvantages of such a unique design.


Unique Handling and Ride Characteristics

Due to the extremely low weight and compact dimensions, the advantages in terms of handling already come into play when launching the boat, because a Thundercat can easily be launched alone without a trailer. Even launching on the beach is no problem, after all, the boats were designed precisely for these conditions. Of course, the same applies to getting the boat out of the water.

In addition, a Thundercat also provides outstanding handling on the water, because the low weight makes any maneuver child’s play and thanks to the speed tubes, the boat runs like on rails and even tight turns at high speeds are possible. The direct tiller steering also ensures that the handling is very direct, and you get great dynamic feedback steering the boat.

The catamaran-style design also makes for a very smooth ride, as a kind of air cushion is created between the hull and the water surface, which has a dampening effect while minimizing friction and maximizing buoyancy. It also prevents the tube from getting sucked down at higher speeds, as is often the case with conventional SIBs (for details read our comparison between SIBs and RIBs).

In the video below includes some stunning drone footage you get a good impression of the great ride characteristics.

Drone Footage of Thundercat

Superb Weight to Power Ratio

As mentioned in the introduction, the Thundercats’ weight-to-power ratio is simply unbeatable. And that, together with the great handling, of course makes for a permanent grin on the water. Some consider Thundercats to be a better alternative to jet skis because of their guaranteed fun, but they are cheaper, more flexible and much cooler.

Great Affordability

In terms of initial investment, Thundercats are relatively budget-friendly, especially when you consider what a tremendous value they offer in terms of fun. They are also very inexpensive to operate and maintain, as there is no need for a permanent berth or even a trailer (though one is clearly recommended), and fuel consumption is also very economical. Any repairs can be carried out on your own, which is also easy on the wallet.

A True Eye Catcher

Despite all these great advantages, Thundercats are still rather rare to find and are therefore often real eye-catchers. In addition, many manufacturers of Thundercats offer a high degree of customization (in terms of color scheme) and you can create a true one-of-a-kind, which in our eyes is another advantage.


Risk of Flipping Over

However, the combination of high speeds and low weight comes with the risk of flipping over with the boat. Especially in wind and waves you should be careful. With the right caution, a Thundercat is nevertheless very safe, and you should not be deterred by its popular use as a racing boat, because it is also very well suited as a recreational boat.

Thundercat racing boat having only contact to the water on one side, almost flipping over
At high speeds, you can easily lose water contact. Source: Infanta Inflatables.

Sacrifices in Recreational Use

Just now we wrote about the fact that a Thundercat is also great as a recreational boat, but certain disadvantages cannot be ignored. For one thing, there is only little space on board for passengers and equipment, and especially for smaller children, safe riding is quite limited. Secondly, the transom is open, which is great for use in the surf, as any water that gets into the boat immediately flows out through the transom. However, not only the water is flushed out, but also everything else that is lying around in the boat and that is not secured. However, if this should really become a problem and you use the boat primarily for recreational purposes, you can easily close the transom.

Note: More information regarding a family-friendly, more leisure-oriented version of the Thundercat can be found further below in this article.

Limited Availability of Outboards

As described above, the choice of outboard motor falls primarily on light, simple 2-stroke models. The problem, however, is that in some parts of the world (e.g., throughout the EU), these can no longer be purchased new by private consumers, as they do not meet the strict emissions regulations. Within these regions, one must rely on the limited second-hand supply or obtain an engine through complicated, not entirely legal means.

Modern 4-strokes are great engines, but they often weigh considerably more and have the problem that they cannot be made ready to run again as quickly and easily as a robust 2-stroke in the event of flipping the boat over.


In the table below we have listed all the advantages and disadvantages once again as an overview.

Unique Handling and Ride CharacteristicsRisk of Flipping Over
Superb Weight to Power RatioSacrifices in Recreational Use
Great AffordabilityLimited Availability of Outboards
A True Eye Catcher 
Advantages and Disadvantages of a Thundercat

Well-Known Manufacturers

Now we would like to introduce you to a few well-known manufacturers of Thundercats.

Gemini Marine

A very large, well-established manufacturer from South Africa that offers not only the popular Zapcat F1, but also many large RIBs.


Caesar Inflatables


Also, a well-known manufacturer from South Africa, who, in addition to their normal Thundercat (the 4.1 Racing Bullet) has developed other variations of the Thundercat, including the impressive 5.3 Maxi, also known as the Thunderbolt, which can be equipped with a whopping 90 horsepower.


Aquarius Inflatables

Another manufacturer from South Africa with a very good reputation, which also offers the Thundercat in different sizes and variations. They have also developed a few RIBs, including a catamaran-style RIB.


Infanta Inflatables

The last famous manufacturer we want to present to you comes, like the others, from South Africa and offers, in addition to its P1 Pencil Thundercat, other significantly larger inflatables.


Bonus: Compromise Between Performance and Recreational Suitability

If you are enthusiastic about the concept of the Thundercats but are not interested in racing and family suitability and practicality are important to you, then we have something for you! Some of the manufacturers listed above offer Thundercats with a “closed nose”. This means that the bow does not consist of a rigid nose cone, but of a continuous tube, just like that of a conventional inflatable boat. Basically, this variation of the Thundercat is no longer a real Thundercat, but rather a normal SIB with the distinctive feature that speed tubes are attached to the hull. The result is an exciting fusion that combines the performance advantages of the Thundercat with the practicality of a normal SIB. Although you must sacrifice a little performance compared to a purebred Thundercat, in many cases this may be perfectly tolerable.

Such a type of inflatable is offered by Ceasar Inflatables with their 4.1 Surfcat, by Aquarius Inflatables with their 4.1m Aquacat Sport Boat, as well as by Gemini Marine with their GRX 420. Zodiac Nautic, probably one of the best-known inflatable boat manufacturers, had similar boats on offer for a long time with their Futura series, but for some time now this has been dropped out of their product range and, as far as we know, can only be purchased through the Zodiac Milpro brand, which is aimed at professionals.

In the following picture you can see a Zodiac Futura competing with a racing boat in 1989. Unfortunately, we do not know how the race ended…

And here is the 4.1m Aquacat Sport Boat from Aquarius Inflatables. At first glance you might think it was a conventional SIB, but take a closer look and you’ll see the speed tubes under the main tube.

That’s Enough, Get on the Water!

We hope to have given you a good overview of these great catamaran-style inflatable boats and maybe we have infected some of you with our enthusiasm! The great thing is that they are relatively affordable compared to many other products in the boating world and still offer a lot of fun on the water. Let’s go, get on the water!

If you have any questions, suggestions, or other input, feel free to leave a comment, we will respond to everyone. We’ll also be happy to help you with some buying advice!

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