There seems to be a belief that your stainless trolling wires must be isolated (insulated) from your boat. Here is a video I made up a while back showing voltage that a fish sees (using 2 meters). I show a caribiner to connect up with. That is a quick and easy method. The picture below is probably a tidier system with a metal tube that the wire goes through and makes contact or a stainless spring that is free floating between drum and block with a connecting wire to it (Cannon used a spring). Anything you use will have to be large enough and strong enough so as not to get fed into your drum or block and making a mess. I will follow up soon with another video explaining a boat's bonding system for those who are interested.

Vide: https://www.youtube.com/watch?v=elDMKAvl0Jg

Here is a link to a short video showing the basics of a bonding system on a small aluminum boat with an outboard. If you were wanting to bond a fiberglass or wood boat to generate downrigger wire voltage, the experts recommend interconnecting virtually all the boats metal and electronic components, both above and below the waterline. Essentially you start with a good quality, low resistance, heavy wire (like welding cable) that is bare of coating and runs the length of the bilge. Connect (preferably soldered) all metal components as listed with #10 or #12 copper wire:
*outboard or sterndrive
*rudder including mounting hardware like packing gland housings.
*skeg
*trim tabs
*keel coolers
*through hull fittings
*engine blocks
*propeller shaft (inboard, using a contact brush)
*kicker motor
*all electronics casings
*radar stand
*anchor winch
*metal rigging
ETC. Connect these all to the bonding wire. A central zinc can be added if you have a lot of metal below water. The amount of zincs can be adjusted in order to find the right amount of voltage needed for your trolling wire. It is possible to over-zinc a boat. Bonding helps to eliminate any stray, nasty bugs that might be costing you fish. Like galvanized bolts on a bronze through hull fitting YIKES! If you don't know what attaching hardware to use ... just ask a commercial fisherman.
Now that you have a happily bonded boat, go back to my first post and connect the downrigger wires to the bonding wire. Test your line voltage by using a short piece of downrigger wire as an extension of your positive probe and touch it in the water a couple of feet from your downrigger wire. Drop your canonball and wire a few feet and contact that wire with negative probe. Meter should be on 2v dc setting. Try this away from boats, engine off, engine on, moving, electronics off, electronics on. See what you have. Canonball should be on a breakaway line and not touching the wire. It really is quite a simple yet effective system.
https://youtu.be/It3UwpZk84Y

or you could just load it up with braid.

That's exactly what I did, and that led me to create my 'portable black box' or Downrigger Electric Field Generator (DEFG) for braided line users. I get asked quite often by customers "should I buy the protable black box or the tuned lures"? My answer is " the DEFG will attract or hold the fish in the vicinity until the lure gets there, but the fish may still reject your lure". I like to think that having both is the desired scenario. I quite often tell people not to buy the DEFG until you try fishing with just one 'voltage tuned' lure. Once you find that most of the fish caught will be on that one lure and now you have faith in the system, then go with the DEFGs and capitalize on having the whole package working for you. Gimmick, some say!!!
I learned this stuff the hard way. My first commercial troller would not catch sockeye to save my life (1982). I was lucky to have survived the first couple of years. That boat fished fine after I got my voltage field sorted out.

Don't over-complicate things and switch to braid...

Maybe it's different in Canada, but in Washington if you are trolling deeper than 20' you don't need to worry about voltage, just good lures, good flashers, and good speed.

Good lures are great. Good lures with voltage is better. I stand by my guarantee. You put one of my 'voltage tuned' lures down there at any depth and fish it beside a plain comparable lure, within say 25 feet, and my 'tuned' lure will come out the winner, or I'll give you your money back.
As far as proper bonding on a boat, the boat's metals form one half of a cell and the stainless wire the other half. When done properly, the voltage travels to the full depth of the wire (not just 20 ft).
Us Canucks do fish deeper than 20 ft. When the killer whales would go through, I found that I could still catch spring salmon when I lowered my cannon balls down to 70 fathoms. There isn't much light down there and a little voltage helps the fish to find your tackle.

Dang your fishing deep 420' (because i was always taught a fathom is equal to 6 feet US Measurement) Not sure of "CANUCK" measurements though.

That was my commercial trolling days, and yup, a fathom is still 6 ft up here. I'm too old to be a metric Canuck. It was common to fish 30 to 40 fathoms daily in Georgia Straights. The killer whales would kill the bite and chase the fish deep. I just moved out and chased em down with my 40 lb cannonballs. They were there!

are there sizes available for Koke fishing?

If you are talking about anodes, my Mini-Hot Anodes are small donuts less than 1/4" outside that slide down the line, over the knot and contact your lure or swivel and hook. Works on spoons, mini hoochies, etc. Gives off about .9 volt (sockeye voltage). See the 'Anode' section on my web page.

witchdoctor