The purpose of this circuit is run a boat bilge blower motor for a predetermined amount of time. The relay is activated by closure of S1, a board mounted switch, or by a momentary +12 V state on the START wire. This wire is best run to the existing blower switch. This circuit is a variation of a Kemo B042 Precision Short Timer. I used the components and PCB that came with the kit with the exception of the relay which was replaced with an off-board Bosch type relay. It should be noted that the capacitors are rated at 16V and upgrading them to ones rated at 20V or higher would be a good idea. A description of the Kemo Kit is available at:

http://www.kemo-electronic.de/

I would recommend the power wire for the board to be fused at 1 amp and the power to the relay be fused as appropriate for the blower motor. By the way, the American Boat and Yacht Council Marine Color Code specifies YELLOW as the correct color for bilge blower wiring.
 

Note:

Transistor BC 237 crosses to NTE 159

See data sheet at:

http://www.nteinc.com/specs/100to199/pdf/nte159.pdf

http://www.cebek.com/cebek/default.htm

http://www.kemo-electronic.de/page2.html