Dave,Looks ok, you can use an automotive relay to power the motor, like one of these..
http://m.ebay.com/itm/2-LOT-TEMCo-1...ss-Socket-Automotive-/381339530351?nav=SEARCH
The TEMco relay came in yesterday... according to your circuit diagram:
the wires didn't come numbered...they came three large wires ( yellow, red and blue ) and two smaller ones ( black and white )...here is the circuit with a switch, relay, overload fuse...
View attachment 101537
also the relay comes into two parts ( part a. the assembly with wires ( CN0174 )and part b. the top part ( CN0171 ) )...
here comes the really newbie question which colored wire goes where...
also... 1. the large wires ( yellow, red and blue wires ) aren't 8 gauge wires ( I bought 8 gauge AWG because... looking at the picture of this relay I knew the wires weren't as big as 8 gauge AWG ) 2. since the relay isn't 8 gauge AWG it is the weakest link into this circuit ( IMHO ( In My Humble Opinion )) 3. Since my battery is a lawn mower battery DC 12 volt 300 CCA and this is just a proto type model the circuit and the motor won't used continually or a heavy demand I decided to go with 8 gauge ... In a real situation ... the correct wire size should be rated at the battery size ( or the demand size ) ... meaning ... My sailboat had a main switch that connected to 4 marine heavy duty size batteries ... the house part of the main switch had 3 marine batteries that would make this circuit toast ( or worst ) if something went wrong ... the 4th battery of the main switch went to the engine ( 37 hp diesel ... the sailboat was 37 foot O'Day and I had electricians do the electrical work )
Lastly... I bought a ammeter from Ebay that is DC 200 volt 300 amp ... where in the circuit should I place it...
Thanx in advance
R