Here are some Photos of old Yumi bow

[Carson (CMB)]

I am hoping to repair and shoot it. Once i get it in my hands, I will have to take a closer look and do some research before I decide to actually attempt to bring it back into service.

[dragonman]

I really respect the craftsmanship of these bows, but the design confuses me and appears clumsy.....does anyone know why or how this design was arrived at  and what are its benefits???

dave

[PlanB]

There's an interesting article on wikipedia on yumi with some discussion of the form and its history.

[loon]

I really respect the craftsmanship of these bows, but the design confuses me and appears clumsy.....does anyone know why or how this design was arrived at  and what are its benefits???

dave

I am guessing that they're probably not that slow since they're narrow and made from bamboo (I really don't get the hardwood laminations on the sides, though O_o), and due to the length, reflex and recurves the draw is likely extremely smooth and long so it gives good energy transfer to pretty heavy arrows for the draw weight

[Dakota Kid]

Plus a bow designed to be shot in a kneeling position makes you a smaller target for the opposing archers.

You should read "zen and the art of archery". It was the original "zen and the art of.." book. The archery is just one facet of kyujutsu which was the samurai "art of archery". Kyudo "the way of the bow" is a more modern adaptation. In the book it was over a month before the student was allowed to touch a bow. It was several more months before the arrows were introduced.

[M-P]

Howdy,  Several observations from my own Kyudo pratice.   
The origin of the design is a frequent topic of debate and speculation, but no one really knows.  The Yumi has been used by kneeling archers, but the original Samuri were HORSE ARCHERS! It seems unlikely that horse mounted guys chose a bow design just so they could get off and kneel.   Most other theories have flaws as well.  My teachers just shrug and say "that's the way Japanese make their bows."
Yumis are designed for long draws.  (My Kyudo arrows are 41 inches long.)  The long draw and remarkable reflex make for an efficient bow, even with the clumsy looking tips.
Yumis are very easy to break with improper shooting and I would worry that a pre WWII bow might delaminate further just from aging of the glue.   I've had garage sale long bows of ~ that age that fell apart at the glue joints. 
I do not know if Jaap does evaluations or repairs, but there is one Yumi maker in CO that does repairs.  (if interested, PM me for more details)

[Dakota Kid]

The shorter lower limb has the same benefit when kneeling as it does on horse back. It doesn't hit the ground or the horse. As you said though, that's just how they make them.

[avcase]

Awhile back, I attended an exhibit of historical Samurai arms and armor.  One detail that I noticed in common is that the Japanese put a tremendous amount of effort into making their warriors look as large and fierce as possible.  My theory is that the goal of making the upper limb so long is visual intimidation.  It has an affect similar to adding very tall extensions to the top of their helmets, or carrying very tall spears with colorful flags or other adornment attached at the top.   I'm sure it makes a strong statement going against a group of archers with 84"+ bows.  The impulse would be to run away rather than fight.  The lower limb is left short so that it doesn't get in the way, and doesn't trip up the archer when it is actually being used.


Alan

[M-P]

avcase has come up with a new explanation!  It makes as much sense as any.   

[loon]

wonder if there are any benefits to an asymmetrical bow and if they draw smoother to a symmetrical bow with the top limb the same length as the bottom on the yumi. Hm. If the bottom limb has to bend more to get its tip to the same vertical line, what is the difference?

[M-P]

Loon, take a look at photos of Kyudo archers at full draw.  The whole bow tips forward so the lower limb does not bend as far as the upper limb. 

[dragonman]

bamboo will easily make a much shorter, more practical bow, japanese bowers must have known this....most archers who train ,manage to hit things with shorter bows,. True they may be smooth and stable...!!  but is there a serious lack of smoothness and stability in a shorter bow?  not realy..!! so what where they thinking???   they obviously wherent stupid because of the skill as craftsmen they display. So, there must be a reason!!!  just cant figure it out.....

[Ruddy Darter]

I think it has a lot to do with the form, they draw high and bring down as they draw so it is always on the shoulders and not the arms for alignment with good form and proper constant maximum length drawing technique and reduce fatigue drawing this way with the yumi , I think the design is to best suit and promote this technique of drawing in my opinion,

Ruddy Darter.

[Urufu_Shinjiro]

I've done a little (although surface level) research in this area and it seems the real answer as unsatisfying as it is is that no one knows why it evolved the way it did. The shape has little to do with horse archery it seems since the tall asymmetrical shape predates japanese horse archery. Some say it originates from using whole bamboo poles or tree saplings and the top of the tree being thinner was left long and the grip close to the bottom to balance the difference in stiffness, though I don't buy that since they had normal symmetrical short and long bows before this design so there was certainly no "need" to string up a "raw" tree to make a bow. Who knows, avcase's idea certainly has merit and would be consistent with japanese thinking but is not the entire story alone either. Meh, the japanese, what'cha gonna do right? lol (I say that as a part time nipponophile so nothing untoward meant by that)