In the chair conformation, all the bond angles are 109° and hence there is no angle strain.  The same may be said of the boat conformation, where all the angles are also 109°. However, it will be seen later that this conformation is higher potential energy than the chair form. In this case, the different groups of hydrogens are shown below (Figure 11).

Figure 11

To understand why the boat conformation has higher energy than the chair conformation, they need to be drawn in the Newmann projection. As can be seen from the Newmann conformational formula, in chair conformation, there is no eclipsing of the C-H bonds. However, in boat conformations, there are several eclipsing interactions. Besides these, there is also an interaction between the two flagstaff hydrogen atoms. These interactions cause the boat conformation to have 25 kJ mol^-1 higher energy than the chair conformation (Figure 12).

Figure 12