You too? So I’m not the only one who can hear water in the back area of the superjet. Specifically, on top of the tray and to the right and left.
Well as it turns out Yamaha filled the halves of the hulls seperately with foam so there is a small gap where water can get in and stay trapped. After time the water will absorb into the foam and cause your superjet to gain a LOT of water. We are talking 8+ pounds of waterlogged foam in the rear of your yamaha!!!
There are two ways to get the water out.
1. If you are lucky and don’t have water logged foam you can drill a couple holes and drain it out. Be sure to close up any gaps in the engine compartment or the seam going around the superjet so that the water doesn’t get back in!
2. You will have to cut open your tray and sides of your superjet and remove all the foam and water. This process takes a while, is messy, and can cost a couple hundred dollars in parts to re foam, and re-glass the rear of your superjet. It’s not uncommon to have to do this and a lot of people will actually sell their ski and find another so they don’t have to do it.
Before you do any of the above I suggest reading the Yamaha SuperJet forums on PWCTOday and X-H20 to find out EXACTLY what you have to do and how long it will take.
Me, I’m doing mine this winter and am going to install some footholds too 
-Todd