In this section, we will discuss basic electrical systems that apply to small marine craft (boats). You, as an Engineman, may be required to perform basic maintenance on an electrical starting system for a small boat engine when an electrician is not available.

Electric starting systems use direct current because electrical energy in this form can be stored in batteries and can be drawn upon when needed. The batterys electrical energy is restored when the battery is charged with an engine-driven generator or alternator.

The main components of the electric starting system are a storage battery, starting motor, and associated control and protective devices. Figure 10-1 shows a typical cranking system.

Figure 10-1.-Electrical cranking system and gear reduction.