Many anglers don't try wind-ons because of the time and effort involved to make the splices. Now, you can buy pre-made, loop-to-loop wind-ons from catalogs like Offshore Angler or Melton. The mono leaders come in sizes ranging from 15-foot, 80-pound leader to 25-foot, 650-pound leader. The fluorocarbon leaders come in sizes ranging from 25-foot, 60-pound to 500-pound leader.
The length of a wind-on leader varies depending on the type of fishing and personal preference. However, most fishermen like the total length of the system to be the maximum allowed by the IGFA: 30 feet.
For lighter leader systems used to troll baits for mahi and striped marlin, it's best to keep the leader on the bait very short, usually about three feet. This helps keep the baits neat and organized in the cooler without lots of leaders getting tangled. For this rig, keep your wind-on at 26 feet for a total leader length of 29 feet, one foot short of IGFA limits for a bit of a safety margin.
Points of caution
A few additional concerns should be considered before you adopt wind-on leaders. First, if you use the smaller-sized AFTCO roller guides, you may have trouble getting Biminis, Albrights or interlocking loops through the rollers. This depends a lot on the size of the monofilament you are using. You won't have this problem when using ceramic ring guides or larger-sized AFTCO roller guides.
While leadering a fish, it's very important that the wind-on leader doesn't slip through your hands. Unlike traditional leaders, the wind-on leader won't stop when you get to the snap swivel, because the snap swivel has been eliminated. If the leader slips past and you suddenly have the main line in your hand, there's a good chance the main line will break.
In heavier wind-ons with Dacron splices, be aware that there is a weak point between where the mono in the splice ends and the Dacron loop in the splice begins. That point is only as strong as the Dacron itself, which may be only 200-pound test.
When using heavier wind-ons, it's very important that the angler wind the line and leader onto the spool evenly. When the wind-on hits the rod tip, the angler must start at one side of the spool and gradually work the leader over to the other side. Depending on how much line is on the reel, you probably won't be able to overlap or cross the leader on the reel's spool. The cross bar of the reel will fray and weaken the interlocking Dacron loop if it hits the bar. Pay attention and check that interlocking loop often to make sure it's not frayed. It won't last forever.
If you haven't used a wind-on before, understand the precautions you must take, but don't be afraid to try it. This is one of the most functional leader systems you can put together. Once you get used to using wind-ons, you'll be hard-pressed to give them up.