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If I'm not mistaken, the red and black wires from the twist lock should run straight back to the battery compartment on the starboard side. You would need to take them off the 12v system and hook them up to your 24v system. If you use two of your batteries for the 24v trolling motor, you won't need the Perko any more because you would need to hook the two batteries in series for 24v and keep them and the twist lock separate from the rest of the electrical system. If your still interested, let me know and I'll go into more detail. Don't forget to put a separate fuse in for the 24v system. I have a 2006 191FS and am about to do the same setup.
Must be nice to have Xmas come early...
Maybe I can get a do over and say to the family...hey, remember when I said I didn't want anything for father's day...I changed my mind...