Composite Decking on a Pontoon Boat Stylishly Replaces Rotted Plywood

Composite Decking - Fortress

High-quality composite decking is durable and moisture-resistant–two things that you’ll need if you want to use it on a pontoon deck.

My all-time favorite weekend was one spent on a rented pontoon boat with close friends, lazily drifting down a river. One of these friends liked the experience so much that he made the effort to get his own pontoon boat. It took him awhile, but he was able to get his hands on one at a price he could afford without having to take out a loan. A little under five thousand dollars got him two aluminum pontoons with a deck of mildewed carpet and rotting plywood that flexed underfoot. He had to buy the trailer separately.

When he had the whole thing parked in his side yard he called me up to take a look at it. I told him right away that there was no saving the decking, or the carpet. He said that he knew, and was thinking about replacing it with slip-resistant composite decking. “On a pontoon boat?” was my disbelieving response. I’d never heard of anything like it, and I had no idea if it would work, or if it was worth trying.

About Pontoon Boats

Pontoon boats are very simple watercraft that depend on two or three hollow, watertight cylinders for buoyancy: the pontoons that give the craft their name. Holding the pontoons together is a frame with a deck built on top. Everything else is bolted to the deck. Propulsion is usually through an outboard motor attached to the back, and the steering links are underneath the deck.

A basic pontoon boat uses an absurdly simple design. As long as the pontoons and the frame that holds them together is intact, the rest of the boat can be cost-effectively replaced with any number of materials. This affordability and interchangeability is unique in watercraft.

Different Types of Decking on Pontoon Boats

Far and away the most common type of deck used on a pontoon boat is a plywood deck with plastic carpeting installed over it. This is not the most appealing combination in terms of look, feel, or longevity. The biggest problem is that the plywood beneath is prone to rotting. Removing everything from the deck and replacing it just seems to be an accepted part of owning a pontoon boat. If you don’t own a pontoon boat, hearing this may give you pause, but it’s actually a pretty easy maintenance schedule, and quite a bit easier than patching the fiberglass hull of a motorboat.

Aluminum decks are often offered on pontoon boats as a more upscale deck material. The drawback to these is that the sound of the water spray hitting the bottom of the deck is quite loud. They also flex a bit more than the wooden versions, and this flexing while the boat is underway can loosen fasteners. Aluminum is also, predictably, much more expensive than plywood, which is partly why plywood decks are far more common. However, the plywood deck isn’t the major complaint pontoon boat owners have about their boats.

The displeasure of boat owners seems to be most often directed at the carpeting that covers the decking. It traps water from swimmers coming back onto the boat, becoming unpleasantly soggy underfoot. One of the more common pontoon boat modifications is replacing the carpeting with non-slip vinyl flooring. Vinyl imitation teak with false boards is one of the most popular choices because it harkens back to the plank decks of sailboats. My friend hoped using composite boards for his new pontoon boat deck would do the same, with some added advantages. The benefit of composite boards is that they are actually boards, rather than a sheet formed to look like boards. This allows those installing the boards to leave a small amount of space between them to let the deck drain. On the other hand, truly waterproof composite decking material is rare to find, and these types of decking haven’t been used frequently enough on boats to give any certainty about how well they work.

Using Composite Decking on a Pontoon Boat

One of the biggest concerns I had about composite was the weight of the composite boards versus the weight of the typical plywood deck. This lasted until I did a Google image search and saw people building cabins and even entire homes on top of a pontoon platform. While composite is significantly heavier than wooden boards–and quite a bit heavier than plywood–it’s not as heavy as an entire structure. Pontoons are amazingly buoyant, and since we were building directly on top of the frame (keeping the weight close to the water line), the additional weight of the composite seemed well within tolerances. I would think twice before using composite decking on the second level of a structure built on pontoons, though. Adding that amount of extra weight high above the water line is not a good idea.

Another major concern was the potential of the composite to flex. Composite decking is less rigid than wood, and even on land some composite systems are famous for their flexing. Removing the old deck laid my fears on this subject to rest. The cross bracing of the frame was 16 inches off-center maximum, with the bracings getting closer together toward the rear of the boat to better support the weight of the engine. If we wanted to run the deck boards diagonally at the rear, we’d technically be within specifications.

The key word there is technically, which leads to an important point about using composite decking on a pontoon boat: there is no way that any composite manufacturer will warranty decking on a pontoon boat. This use is just too different from what composite was originally intended for. Installing composite on a pontoon boat is always going to be an out-of-pocket expense and an experiment. For that reason, it is important to use a composite that’s high quality with a full cap that protects it from moisture above and below to give it a chance of lasting long enough to be worth the cost.

What to Look for in Composite for a Pontoon Deck

In the end, my friend decided it was worth giving composite a try. We purchased the boards, ran them lengthwise, and use the manufacturer’s hidden fastener system to hold them down. This resulted in a sharp-looking, smooth deck without any danger of popped nails or screws. We did end up with gaps between the boards. We were worried about water splashing up between the boards, and whether or not the hidden clips would hold the board when the boat was moving and vibrating. On our test run, though, there were no noticeable issues with splashing water or with bouncing boards, and the gap between the boards let puddles drain rapidly. A year later, and my friend hasn’t had much of a problem with his new boat deck. However, using composite on the deck is very much an experiment, and it remains to be seen if it continues to hold up.

Putting composite decking on a pontoon boat is an uncertain prospect, but, as my friend learned it can have beautiful results. If you’re interested in giving it a try, look for composite with features that will help it stand up to moisture and will make it an appealing surface for bare feet. A fully capped composite board is a must, as the capping will protect the core of the board from moisture coming from all sides. Hidden fasteners are optional but make for a very smooth deck that’s barefoot friendly. Since they don’t pierce the board, hidden fastener systems also help keep the water-resistant cap intact. Another feature to look for is a slightly rubbery capping, which feels both more natural and more pleasant than the slick surface of vinyl, and isn’t as likely to contribute to slips and falls.

One composite system that has all of these features is Infinity decking by Fortress Deck. Infinity is a fully capped, bamboo-based composite decking system that’s designed for extreme durability in almost any situation. This composite is carefully engineered to resist moisture, UV rays, and wear and tear. To find out more, contact Fortress Deck or look for a dealer near you. And, take a look at Fortress Building Products other stylish, durable offerings.

Leave a Comment

You must be logged in to post a comment.