thank you Friends.. its so fun with her.. can operate even from a wash basin..
the rudder surface is fixed.. and i made a centrifugal thrust pump, with a bottle cap, that holds a simple foam board disc, with four simple blades are glued.. you can see an opening at the front side of the cap, to expel the water, through either side, when the disc rotates either direction.. when disc rotates, water shoots out one direction, makes an thrust reaction that turns the boat.. so effective in all crafts.. and toy radios works only as on and off, this arrangement is so easy, but works well.. we can also make simple crafts, while turning servos as gear boxes, in continues mode.. with hobby radio.. its so easy..