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High-quality fishing tackle directly from Japan to worldwide. All prices are in US$.

Drill spools!!

1. Reduce spool weight

    Were you first attracted by the wiffle, or drilled spool of Shimano Japan domestic models? You are in almost right track. The most significant difference between Shimano US models and Shimano Japan models is the castability.

Spool of Shimano Scorpion 1000

Castability is decided by 3 major factors. They are 1)brake system, 2)ball bearings(lubrication), and 3)the moment of inertia of spool. As Metanium/ Chronarch reel had advanced, spool design has been changed to hold more drilled holes and thinner spool edge. It has been the challenge to reduce the moment of spool. The reason Shimano reels have great castability is that it greatly reduced the moment of spool. (correctly, the moment of inertia of spinning parts related to casting)

    As spool has less inertia, the reels has better castability, because first it needs less power to accelerate the spool in the beginning of casting, and second it needs less brake force to control the spool speed. Adding to this, with less inertia, the spool will stop faster when lure reduced speed unexpectedly.

Inertia of spool

     Inertia of spool in casting is coming from two sources, spool itself and line spooled. The more weight, the more inertia.

Following table shows the weight of spools.

Normal Spool

Wiffle Spool

Wiffle SF Spool 1

Wiffle SF Spool 2


Chronarch 100A

Metanium XT Red

Metanium XT Silver

Metanium MG






Weight with full nylon line





*1) Data excludes the ball bearing on the shaft

*2) 1oz=28g

    Normal spool has the most weight, and the spool of Metnaium MG has the least. Moment of inertial depends on weight and distance from the center shaft, and if the shape is the same, the more weight the more inertia. Now we need to consider the inertia from lines.  Wiffle spools fit 140y of 0.285mm dia line, and the line weighs at 10.2g. The normal spool fits 170y. The 30y difference adds 2.0 g to the normal spool.

    3 spools of Metanium have the same capacity, and total inertia depends on the weight of spool. Spool weight is concentrated near the center of shaft, and it has relatively less significance to inertia though.

For reference, I added the date of Antares/Calais MG spool.


How to achieve ultimate castability with your reel?

1. Spool lighter line. Fluorocarbon is about 50% heavier than nylon. If you spool fluorocarbon fully, you'll adds significant moment of inertia to the spool. Spooling braid backing and short fluorocarbon, like 75yards, will improve castability. Putting line saver, like cork tape on shaft, will significantly reduces the moment of spool.

2. Don't spool line to the edge. Weight at distance from shaft adds more inertia than weight near shaft. By spooling 30y less line, your spool has the same effect of 8g weight reduction at spool shaft.

3. Change spool to lighter, upper graded one. Spools from Shimano is pricy, but I strongly recommend this especially to the user of Chronarch 100A. It is equipped with the normal spool and interchangeable to Metanium XT red spool. For Chronarch SF, Metanium MG's spool is interchangeable. Magnesium spools are the ultimate solution. Currently B-Trap offers magnesium spools for Daiwa casting reels, and ABU SX reels.

Another pricy solution

Shimano also has introduced special tuned spool for Metanium silver and MG. It has cut the brake bracket to hold only two blocks. The base spool is Metnaium MG's, and interchangeable to Chronarch SF, Metnaium silver, and Chronarch MG. Price is about $90.

4. Drilling spool by your self? The effect of weight reduction near spool shaft is less than that at distant from the shaft. Even if you've drilled 10 holes on your Chronarch 100A spool, it's effect will be relatively limited. Adding to this, maintaining dynamic balance of drilled spool is almost impossible without a special tool. Not recommended.

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