Astronomical sketching is much easier if your telescope "follows" the objects in the sky. Star tracking is generally not available on dobsonian telecopes unless the telescope is placed on a so called equatorial platform. An EQ platform basically is a low rotating table carrying a telescope. The working principle is very well documented on the home page of Reiner Vogel (German).

The advantage of an EQ platform is the possibility to enjoy the comfort of a star tracking system while preserving the "dobson feeling". This means that objects can be found quickly just by grabbing the telescope by hand and move it to the appropriate point at the sky. As soon as the telescope is positioned, it sticks there without losing the object because the equatorial platform compensates earth rotation.

I build two EQ platforms of my own: a prototype (the black one) and an improved final version :