In the modern age, almost every pontoon boat that is constructed is made from aluminum. The reason that companies and boat manufacturers use aluminum is that it is a very light metal, and it does not rust at all. To make the log shaped pontoons, sheets of aluminum are rolled and then welded into cylinders. The cylinders do not cover the boat from aft to stern, they slant upwards as they get to the stern of the boat, this is necessary so the boat will be able to move forward with a very small amount of resistance.
If they were just flat you would need a lot more power to move the boat, and that would be poor design as you would be wasting money on fuel. There are anywhere from 2-3 cylinders, but actually there are a lot more than that. Just to make up one, several cylinders are welded together with each having its own water tight compartment, so if a hole gets punctured in one of the cylinders then there are many more water tight compartments to keep the boat afloat.
Boat builders can choose from different kinds of aluminum, it will all depend on what size boat that they will be building. It isn’t extremely important on what grade aluminum is used if you plan on using the pontoon boat in freshwater. But if you plan on using the pontoon boat for saltwater you will want the highest quality that you can get, as saltwater has the tendency to corrode metal.
There are three main types of logs that are used on pontoon boats, these are the traditional round logs, U-shaped logs, and boat shaped bottom logs. The boat shaped bottom logs, or pontoons, are made for speed, so if you want a boat that travels fast you may want to look into a boat that has these. The traditional rounded logs are rarely used these days in pontoon construction as there are many other factors that can be easily upgraded to contribute to better speed, and better deck attachment. U-shaped logs are probably the most popular logs that are used in pontoon construction, as they provide great buoyancy and are easier to assemble to the beams that connect the 2 or 3 pontoon logs.
The 2 or three pontoon logs are attached together by aluminum bridge beams, and they are generally 16 inches apart. The beams are either connected to the pontoon logs by means of welding, or by nuts and bolts. If the boat is using nuts and bolts then they will have to be inspected annually to make sure that they are still tight, while if the cross beams are welded onto the pontoon logs there would be no need to check up on the tightness.
Once the beams are intact then a boat builder will start adding the deck, which is almost always made of plywood that has been pressure treated so the wood will not rot. A few reasons why boat builders use plywood as a deck over metal are metal decks get hot easier, this would be bad on a hot sunny day. Another reason is that would absorb vibrations and sound a whole lot better than metal does.
Once the deck is mounted onto the cross beams it is usually outline in a finished aluminum for looks and support, and they marine carpet is added on top of the deck also in most cases. From there the boat builder could install railing and furniture on the boat which is mounted to the deck, now for the main design all that is left to do is install the motor.
Pontoon boats almost always use outboard motors, and the mounting of the motor is easily done by use of a motor mount that is installed between the pontoon logs. I have not seen many pontoon boats that have more than one outboard motor installed on them but I am sure that it possible and there are some out there with dual motors.
Now that the main design is done there are many other things that could be added to the pontoon boat. For instance Crest along with other pontoon boat manufacturer’s have models where an aluminum sundeck is mounted to the frame, giving the pontoon boat another floor. Ladders are often installed on new pontoon boats, and can easily be installed if you have a boat without one.