You should always run your inflatable boats with the tubes fully inflated. Running your boat with the tubes under inflated causes extra stress on the seams of the tubes as well as stresses the hull in areas that were not designed to take the full amount of pressure exerted on the tubes as the boat moves though the water. The typical operating pressure is about 3 PSI. If you are using a hand or foot pump, the maximum that your pump will allow is around 3 PSI. Your pump should have a label with it's max PSI on it.
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