Copper strap is a very poor choice for a bonding system if you so choose to have one. Since the copper straps go to the aft section of your boat and aren't connected to anything there, it's likely that there was an HF antenna tuner there at one time that the straps would have been connected to. Bonding is a controversial subject. It's use has to do with managing destructive galvanic and stray currents. The term, "electrolysis", while commonly used, is a misnomer in this regard.