A number of foamed plastic materials are widely used in boat hulls, as well as in home- built aircraft. They are a bit higher in cost, but are lighter and easy to work with. Each of these material families has a set of mechanical properties, physical properties, working and handling characteristics, and a cost structure all of their own. In addition to the differences from one chemical type to another, there may also be major differences between the low-density and high-density members of the same family. Cost and performance will need to be considered for each case.
Be aware that these materials have relatively low softening temperatures, and in the hot South African sun, we need to be careful. Even the paint colour of the final product needs consideration, as dark colours are a problem.
A few of the more commonly used foam materials are discussed in the paragraphs below, along with some of the characteristics which distinguish them.