How do I convince my mom to let me set up my swimming pool?

Ok ever since christmas I have asked my mom to let me set up our easy set swimming pool and she has said yes until the day me and my mom went to storage to get it out so we could set it up we came home and my stepdad asked why we went to storage so my mom told him we got the pool up and what does he say NO because he thinks someone will jump over the fence and jump in our pool and sew us for getting hurt but i just wanted to tell him you need to get back to reality becuase noone will do that, we keep our bikes out unlocked and we live a on a busy street for 2 years and no one has stolen our bikes. I have asked my mom a lot of times after that and she always agrees with my stupid stepdad and says no I have tried everthing to get her to say yes and she just wont she always say I will talk to troy, btw troy is my stepdad and then he says no like always! So what else should I do I wont take no for an answer. If I dont get to set my pool up then my whole summer will be ruined no matter if I go to the public pool I just want my own set up pool and we have it so why dont we accually use it??? PLEASE HELP ME!!!! THANKS :)