What Can I Use as an Aquatic Foam Substitute?

All mass-produced boat manufacturers must engineer their vessels and add floatation material such as polystyrene foam that will keep the boat from sinking if it gets swamped. Boat owners need to remove a portion of the foam when customizing the craft to their personal needs. Mice or other rodents can get in a stored boat and chew up the floatation foam. Other problems can occur, necessitating the addition of floatation material to ensure that the vessel remains safe to use. Boat manufacturers use products specifically engineered for marine purposes, but you have other options.

  1. Polystyrene Insulation

    • Polystyrene insulation, the most well-known brand name being Styrofoam, comes in a variety of shapes and thicknesses. Cut the insulation panels to the shape and dimensions you need, then secure them so they won't easily float free if your boat gets swamped.

    Insulating Foam

    • Several companies make a product that sprays out of a can as a thick liquid, thenrapidly expands and turns into a waterproof foam. Homeowners use this to fill cracks, seal windows and for other weatherproofing purposes. The foam expands to about 20 times its size when exposed to air and moisture. If you have a location needing more floatation material, spray in a layer, wait a few minutes until the application has expanded, then add more until you fill the space to capacity.

    Encapsulated Air

    • Foam works as floatation because it is made of millions of tiny pockets of air encapsulated by the surrounding plastic. It's the air that makes it float, not the plastic. You can construct or install air-tight/water-tight compartments constructed from plastic, metal or fiberglass on boats. These compartments will add to a boat's floatation without using foam. Be careful, however. If even a tiny hole occurs in the compartment's exterior wall, it will no longer be air and water tight and may fill with water in an emergency situation.

    Other Materials

    • Any solid material less dense than water will float. Some plastics are less dense than water. Many wood products are less dense, but most wood floats because it's not really solid, but because it contains air. That's why it can become water-logged and sink. You can use any substance less dense than water as floatation material. Few materials do a better job than encapsulated air, whether it's a water-tight compartment or encapsulated air in foam products.