I'm guessing he was hoping he could get it out pretty quickly - however she may notice tire tracks around the pool. But even so, I'm sure she'd be more sympathetic to the situation of she knew he dropped the mower in the pool, but manned up and got it out and cleaned up after himself, rather than coming home finding him sitting in front of the TV sipping another brew and breaking it to her that they can now mow the bottom of the pool.