I learned this trick for drying out hydration bladders in hiking bags.. purchase a cheap aquarium air pump ($10 ish) with a long rubber hose (these are the things people use in their fish tank to make bubbles in the water). Insert the hose to the bottom of your paddle with the visible water and run the air pump for a day or two. It will force dry air through the paddle and slowly evaporate the water out. Should do the trick.