Tom, We;ve tried this a few times on Dave's boat and did it again on Monday. Still no luck, but here's our rig...
This is for trolling 15+ knots...
Like George said you need a heavy lure to start. You also want it to have flash and be dark so that it can be seen through all the white water behind the boat. I use my 'Heavy D' with wings a nd a colorado blade at the end of the hook for extra flash(pictured below). You can use any type of jet head, cone head shaped lure. Make sure its got some weight to it though. At slower speeds(up to 14 kts) you can even use lures rigged with natural baits, like Islanders. The lures over the baits help prevent washout. Just run these back further from the boat to help with tracking. Colors..purple/black, green/black, purple silver, etc.
Since we're after primarily wahoo, we use cable through the lure to the hook. Some use single strand, but that can kink. I like the 49 strand cable...it acts like mono and won't kink like single strand. I use any where from 175 # up to 225 to 300#...mostly the 175-225#. Crimp on your hook, space it out from the neck of the lure head so the point of the hook is just past the end of the skirt. I then leave about 2-3 feet of cable in front of the lure and crimp on a barrel swivel. To that swivel I'll attach a length of 150-200# mono approx 10 feet. The other end of the mono gets a crimped loop. You can also do all cable if you want. I've rigged many with 10 feet of cable right to the trolling sinker's snap swivel. Mono might help for those shy fish, but at 18 knots I doubt they see the cable. Thats your basic rig.
Now trolling... the rig gets finished off with a cigar trolling weight, 10-28+ oz. Many of these come with a snap swivel already attached. I have learned from experience to take that snap off and attach a length of cable(12 inches) on each side of the cigar weight. Wahoo have been known to hit the trolling weight and cut off the entire rig. Sometimes you can find trolling cigars made with cable running all the way through the weight...these are the best. Put a snap swivel at one end of the cable lengths and a loop on the other. The snap end will attach to your lure's mono loop and the other to your main line.
Trolling, we're running any where from 15 to near 20 knots. We'll run two lines off the flat position. We've got bent butt 80's out there to handle the drag. You can easily do this with lighter gear, just have to downsize the weights and back off the throttle some. Bent butts keep the line closer to the water allowing the lure to stay in the water better...but can be done with straghts as well. Drags are set just past where the line doesn't inch off the reel. Any tighter and you can pull the hook threw the fish's face at these speeds. Run these back far from the boat. They should track straight just under the surface. If the lures are jumping out of the water with weights in tow, drop them back even more or slow down a hair. Remember with any trolling pattern, you can increase speed and still maintain the lures/baits same presentation/action by dropping them back further...thus covering more ground.
Hope this helps. This is something I'd like to do more off...espeically to see a wahoo sky on one the the baits traveling 17 knots!!
Catch 'em Up!!
