It's impossible to separte the hulls and the desk without destroy the Batboat. Hulls and desk are assembled with a strong glue !!!

So it's possible to remove the steering wheel, canopy and dasboard without open the Batboat. It's easy, the steering wheel, canopy and dasboard are not glued just assembled. For take pictures, and understand how change the steering wheel, the canopy or the dasboard this Batboat are opened BUT IT'S NOT necessary.

For remove parts :

1 - Pull up the dashboard and go away first by Robin side, and by Batman side.
2 - Pull down the canopy, it's fixed left and right by 2 little peg.
3 - Remove the steering wheel

Removed parts, look inside the dashboard it's write "BOAT" :

For reassemble parts (NO GLUE) :

1 - Up the steering wheel
2 - Up the canopy, it's fixed left and right by 2 little peg.
3 - Up the dashboard, first by Batman side and second by Robin side

So I don't understand why spare parts are not the same that original, why this 2 sides !!!