Trampolines on a Catamaran: Full Explanation


Just as you probably are right now, I wondered what that weird net in the front of the catamaran is and what it does, it looks fun, but surely that’s not why they put it there? Finding the answer to that seemingly simple question was harder than I thought, but now that I have figured it out, I want to share my knowledge.

The squared nets on the picture are called trampolines

A trampoline on a catamaran is a squared net at the bow with two functions that enhance the boat’s safety and handling. Firstly, it allows for water to pass through. Secondly, it reduces the structural weight forward of the mast. Trampolines can also be used as a place to sit and relax

Continue reading to understand why this is important and how it works.

  1. Contrary to a solid deck, a trampoline creates the possibility for water to pass through, thus significantly reducing the amount of water that can weigh down on the bows in the situation where the bow gets buried after semi-surfing a wave.
  2. A trampoline reduces the structural weight forward of the mast, which moves the center of gravity towards the middle of the boat, limiting the pitching effect and reducing the risk of burying the bows.

Now that we know what it does; let’s dig a little deeper and see if we can figure out how it works. Researching this post, I had to look further than I usually have to.

Google is usually my best friend, but this time it let me down! Many of the forums discuss the trampoline out of a comfort perspective, nothing wrong with that, but by asking a few more questions and looking a little bit further, I realized that it isn’t about esthetics or comfort; it’s all about safety.

Trampolines aren’t like choosing a safer car, it’s more like should I drive on the right or left side of the road! ok, that one wasn’t any good; what I’m trying to say is that having a trampoline instead of having a solid deck is a big deal. Here is why

Trampoline benefits explained

Quickly removing water from the bows

Looking back at function number one, water’s ability to pass through, this is essential since catamarans can surf down waves in big seas at great speeds. There is a possibility that the bows will be buried once the boat reaches the bottom of the wave, thus putting a lot of extra weight in the bow at the same time as the boat is braking and the wave is pushing it even deeper. At this moment, it’s of the highest importance to remove that pressure on the bow as soon as possible. With a solid deck, the water needs to pass over, and around the boat, this takes time, and time is at a premium in a situation like this.

On the other hand, with a trampoline, the weight of water pressing down can’t be equally high since part of the net is just an empty hole, and empty holes are not a part of the bow, so this area is subtracted from possible square meters of pressure from the weight of water.

This means not only that the possible area where water can stay is lower, but it also means that water now has a second option, to go down. This shortens the time when the bows are under load and in danger of a big wave flipping it over. It basically works as a fishing net, but you are the fish, and only water can pass through! Ha nailed it!

Reducing the risk of burying the bows

So we have talked about what could happen if we do bury the bows, reducing this from happening should be one of our highest priorities if we want to have a safe time on the ocean.

Personally, I think that Eric Smith of atlantic-cruising.com does a great job explaining how catamarans are using physics to their advantage. One point he makes is the importance of the center of balance to reduce pitching(the motion of a seesaw). Just as with a car, there is a need for a low and centered point of balance to minimize the risk of flipping or capsizing. On a car, that’s easier; on a catamaran, it’s a little bit more difficult; on the one hand, you want a low boat for a low and centered center of gravity(stability).

On the other hand, you want a high boat(less stable) so there is a possibility for the waves to pass under reducing the risk of waves slamming into the hull creating horrible banging noises and extra wear.

Knowing all this, it makes sense to replace the very heavy glass fiber piece with a lightweight, water penetrating net and thus not only reducing the catamarans weight (which, by the way, also makes it faster) but also moving the center of gravity towards the center of the boat reducing pitch and decreasing the risk of burying the bows. All of this reduces the risk of capsizing.

Another great benefit of having a boat that doesn’t pitch as much as the decrease in seasickness, which isn’t just nice; in many ways, seasickness makes you tired, makes bad decisions, and ultimately might be a safety issue.

So if removing that water is so important, why is there not just a big hole? Good question; I would argue that there are several reasons; one is that sailing the boat will require you to move all the way to the bow of the boat, and in this case, the trampoline acts as a floor, hindering you from having to balance around and possibly falling into the sea.

Another reason is that it also adds structural integrity; during a hard sail, there might be an outward pushing force acting on the hulls. This is counteracted through the tensioning of the net. This force is also countered with the cross beams, which are the main supports.

What about beer and stuff?

Yes, beer, sorry for all the technical nonsense; I’m just trying to keep you safe :). OK, here comes the interesting part, the beer part, so basically, the one huge benefit of having a solid deck is that there is plenty of room to drink beer and hang out. This is especially important on smaller boats where there is limited room on the aft.

Risks aside, having a big deck could really be a game-changer when it comes to the social aspects of a sail. If the boat isn’t used for crossing the Atlantic every Thursday, then it is definitely something that brings a lot of value to your trip. Sailing coastal, I would go with a solid deck, and for the great seas, I would choose trampolines.

Netting forward rather than solid decking is crucial for an offshore cat‐for comfort and for safety!

Eric Smith of atlantic-cruising.com

Gabo

Owner of CatamaranFreedom.com. A minimalist that has lived in a caravan in Sweden, 35ft Monohull in the Bahamas, and right now in his self-built Van. He just started the next adventure, to circumnavigate the world on a Catamaran!

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