A man or older boy is standing up in a blue and white speedboat that's parked in a driveway.
The man and boy are pretending that their boat is in a race.
We cannot be certain why they're standing like that on the boat unless we ask them, which sentence 1 gives no info on. The man and boy may not even have a connection to one another.
exists e2 e1 s1 s2 s3 x1 x2 x3 x4.(in(e1,x2) & in(e2,x4) & n_driveway(x4) & Theme(e2,x3) & v_park(e2) & (x2 = x3) & n_speedboat(x2) & a_white(s3) & Theme(s3,x2) & a_blue(s2) & Theme(s2,x2) & a_up(s1) & Manner(e1,s1) & Actor(e1,x1) & v_stand(e1) & (n_man(x1) | exists s4.(n_boy(x1) & r_more(s4) & a_older(s4) & Theme(s4,x1))))
exists e1 p1 x1 x2 x3 x4.(n_boat(x4) & of(x4,x2) & n_thing(x2) & n_boy(x3) & n_man(x2) & subset_of(x3,x1) & subset_of(x2,x1) & Topic(e1,p1) & Actor(e1,x1) & v_pretend(e1) & exists p2 x5.(in(x4,x5) & n_race(x5)))