Yumi
From Karate, Kungfu, Wrestling, Mixed Fighting Information Source
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The Japanese Long Bow or Yumi is a very interesting version of the longbow. This bow was designed to be shot from horseback, so instead of having the grip in the middle of the bow, it is closer to the bottom of the bow. The bow is typically 6 foot long or more. This is a difficult bow to master, but a fun one to watch someone shoot properly (or improperly).
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History
Characteristics
It has an asymmetrical design allows the wrist and bow hand to be in perfect alignment at full draw, making for an accurate and sweet shooting bow. Its great length also allowed for a long draw which greatly increased arrow speed and power. Though the days of the Samurai warriors have long sinced passed, this bow is still used for the practice of a martial art call Kyudo (Japanese archery), which is growing rapidly.
Types of Yumi
There are two basic types of Yumi in use today:
Bamboo Yumi
- The bow of choice for most kyudo practitioners is the standard bamboo yumi which is made today very much the same as it was 500 years ago. With its simplicity and clean lines the bamboo yumi is unsurpassed in beauty and elegance.
- A bamboo bow is not particularly delicate but it is susceptible to extremes of climate and physical abuse. For this reason, many schools and kyudo clubs recommend that novice practitioners use synthetic bows. Generally speaking, kyudo should be practiced with natural materials but a bamboo yumi is quite expensive, costing upwards of six or seven hundred dollars. For beginners, who have not yet perfected the technique of shooting a Japanese bow, the potential for damaging an expensive bamboo bow is high. Bows made from carbon-fiber or fiberglass-covered wood are a durable, less expensive alternative. These bows usually cost less than four hundred dollars and are practically indestructible given normal use.
Lacquered Yumi
- Lacquered yumi, are special-made by only a few bowmakers today. As a result, they are extremely expensive, often costing two or three thousand dollars or more. Consequently, they are generally used only for special ceremonies, and then only by the most advanced of practitioners. Yumi are available in a variety of lengths and pull strengths. Most beginners start with a yumi that has a pull of ten or twelve kilograms. After a year or more of practice they will then move up to bow with a higher pull strength. On average, an experienced female practitioner will use a yumi of fourteen to sixteen kilograms, while a male practitioner will use a yumi with a slightly greater pull strength, around eighteen to twenty kilograms.
The Use of Yumi
At the beginning of the shot, the limbs and arrow accelerate towards the target. There is a large reaction force imparted by the grip on the hand towards the archer. This disagreeable sensation is called handshock. At the "end" of the shot, the arrow is leaving the bow, having received all the momentum it's going to get, and the limbs are violently decelerated as the string maps back into a straight line. By conservation of momentum, the grip now tries to hurdle forward. The bow falls to the ground unless captured by a restraining device like a wrist strap, or by simply grabbing the grip tightly.
In Kyudo, the bow is held in a very light, delicate manner called "tenoche". Given the spirit and intentions of Kyudo meditation, a forceful grabbing of the yumi is inconceivable. Now if one applies the delicate "tenoche" grip of Kyudo to shoot a symmetric long bow, the bow simply rips past the delicately placed fingers of the tenoche grip and drops to the floor.
