I have a 1977 arrowglass nova I am running a 12v trolling motor I would like run a 24v trolling motor
first question is the switch I have pointed out in pic a toggle switch that has been broken off
if so what does it do
next how would I go about setting up for a 24v trolling motor
feel free to asking question I am sure I have left out important info I am mechanically inclined just not electrically inclined so any help would be appreciated
thanks

That switch allowed you to choose 12 or 24 volts. It effectively doubled the number of speeds that the motor had. With the age of the boat, I'd not use it or any of the current wiring. I'd buy some 6 gauge wire and run it from the batteries to the front of the boat and install a plug in for the trolling motor.

To get 24 volts you need 2 12v deep cycle batteries hooked up in series. That is running one wire from the positive of battery 1 to the plug in. Then run the other wire from the negative of battery 2 to the plug in. Finally put a jumper wire from battery 1 negative to battery to positive.

Thanks for the help dayne let me ask about charging do I need to hook a charger up to each battery or will charging one also charge the other
also can I hook up my fish finder to the 24v battery I have a 788 hd ci

You will want to keep a dedicated cranking/accessory battery for the depth finders, outboard and any other accessories. The trolling motor batteries will be connected in series to provide the 24V. The new wiring 6ga advice above is good. You will need to charge each battery individually, or invest in a multi bank charger.
John