Occasionally kayaks of all types will develop indentations in their hulls - these indentations are sometimes referred to as “oil canning”, because they tend to pop in and pop out under pressure – similar to an oil can. Typically these indentations are due to improper storage or transport. Things like storing a boat flat on its hull or tying it on a car rack so that another boat or the rack itself pushes against the hull invite such indentations.
To remove a dent, set the boat in the direct HOT sun for a couple of hours with the dented area exposed. This process should be allowed to proceed for at least two hours. When the hull heats up, it usually reforms itself, but you may have to get creative with some weights or braces inside the boat to push the dents back out. Another method is to use your hands to push from the sides of the indentation to allow the center of the dent to pop back into shape. In the absence of HOT sun another way to remove a dent is to use a heat gun, hair dryer or HOT water to heat the dented area. Be careful to only heat the plastic to a soft state without burning or melting it. This will allow you to push the dent out and the hull should retain its original shape. The above methods can also be applied to dents in the side or chine of the kayak. These are often noticed after the boat is removed from vertical transport on a roof rack.
To prevent such dents in the future, be sure to store your boat either vertically, or on its side – never flat on the hull – and to be mindful of the hull during transportation.