Sailing a PAckraft with an Umbrella

I’ve been experimenting with umbrellas as a sail on my yak and it has been really good fun. Cheap umbrellas didn’t work as they fold back up but I got this sturdy one here in Thailand that has a rigid frame. I use my paddle as a rudder and off I go. It has been working great at sea and on bays but the metal parts are getting really rusty fast.