Proper spooling technique based upon line type and reel type is extremely critical for optimum performance of both the line and reel. Some reels, such as centerpin reels, require certain weight considerations to provide for perfect freespool performance. Other line types and reels have other tension and spooling speed requirements. In any situation knowing what you are dealing with and how to properly fill your reels is key to success.
Most centerpin reels found on the market today are in the 4-5" diameter range. Centerpins are designed to freespool line off the reel to allow for a natural drift of your float presentation without any interruption in payoff of the line until the reel is hand braked.
Centerpin Reel Spooling
Do not ever toss the spool of line on the floor and start reeling! You will be creating massive amounts of line twist as you spool.
Stating the obvious, the float fishing mainline is supposed to come off the BOTTOM of the centerpin reel when fishing. Therefore, it must be spooled onto the bottom of the reel from your feeder spool of floating mono. As with any other non-spinning reel, the line must come off the feeder spool and on to the fishing reel the same way. In the case of a centerpin, this means "bottom to bottom".
It certainly helps to have assistance when spooling any reel, centerpin included. The most obvious and easy method for spooling a centerpin is to have a partner hold the feeder spool with a screwdriver through the middle and the line coming off the bottom of the feeder spool.
Thread the line through the rod guides and on to the bottom of the centerpin reel. Apply moderate pressure to the float fishing mainline as it travels onto the centerpin reel by pinching the line with your fingers. Pinching the line will also help in guiding the line onto the reel in a uniform and level fashion so you don't pile up all of your mainline on one side of the reel.
Proper tension when putting line onto the reel is also important for smooth payout while drifting your float. This also applies to when you are actually fishing. Every couple of drifts, pinch the line under some decent tension as you put it back onto your reel...don't just freewheel it every time. Pinching the line under tension will help push out some twist that you are creating by side casting, will push water off the line, and firmly pack the line back onto the reel for more smooth payout in subsequent drifts.
No more or less than 2-300 yards of floating mono mainline should be spooled onto any centerpin at any time. You must keep more weight to the outside of the reel to provide for rotation continuum. Lightweight Bloodline braid used as backing will keep that weight balance (from the heavier floating mono) further away from the centerpin reel arbor and will keep you reel spinning freely. Too many anglers put way to much mono mainline on their reels because they constantly strip due to line twist from side casting, but end up not putting their reel in the best possible rotation scenario. If you are only doing super short drifts that is probably fine, but for moderate to long drifts you need proper weight balance on the centerpin.
Finally, do not over or under fill your centerpin reel. Most centerpin reels will have some kind of a groove or marking etched in the inside of the reel spool near the top. If you over fill, it will cause relentless cascading of line over the top of the reel while casting which will cause huge tangles. Under filling your centerpin reel will cause problems when side casting as too much lift is required to get the line up and over the lip of the reel. 200 yards of Bloodline braid as backing and 200 yards of Floating Mono mainline will perfectly fill most centerpin reel setups.
It takes some time to spool your centerpin reel and periodically maintain your line while fishing, but these are delicate fishing objects that will perform best when properly spooled with the correct amount of line, tension and technique