Weight to draw to length ratio?

[SMeeres3030]

Hi I'm am curious if there is some ratio or rules or guidelines to follow for length of bow to draw length? I finally broke my very first bow I made! So sad. It was a yew self bow 58" ntn 72# @ 30.5".
I've shot it for 1 year now and it started ticking yesterday when shooting. It may have been from extreme cold -26c but it ticked them boom into 10+ pieces. Anyway I have a few more in the making but just hoping for feed back.

[bradsmith2010]

yes you went way past the ratio,, you need about 68 to 70 inches for a self bow,,to draw 30 inches,,

[Badger]

  Its not just an issue of over stressing wood which is very important but also too short of a bow will stack at longer draw lengths. You get low energy output ratio for your peak draw weight.

[burtonridr]

Sorry to hear your bow broke, that is always frustrating...

To answer your question, as to what I understand, there really isn't a ratio or rule of thumb even for weight to draw to length. There are a lot of variables that can affect those measurements. The bid one that comes to mind is the type of wood, since each type of wood has its own compression and elasticity properties. I'm also not sure how you could have such a ratio because it doesn't take into account limb thickness, width or profile. You change any one factor and it can affect the others.

However, there are often plans available to give you a good staring point depending upon what type of bow and what type of wood you want to use.

I have not used yew, but from what I have read they usually are long and 'D' profile... 58" sounds short.

[bubby]

Generally with a rigid riser the length of the riser plus double the draw length so in your case 61" plus say 10" . On a bendy double your draw length these are generally accepted guidlines but nothing is hard and fast

[PatM]

I don't think bows need to be anywhere near as long as people are suggesting to reach 30 plus inches but they do need to be over 58".

[SMeeres3030]

Ok thanks guys . I primarily use yew as it is readily avalible! And 58" is too short? I was hoping for a shorter bow to take hunting as it is usually fairly dense brush and it would be easier to manoeuvre around. I have one in the works now which is 70" ntn but seems very long to be packing in the bush.? I will start a new topic this evening with some pics!

[bradsmith2010]

you can make a 60 inch bow if you sinew back it,,and draw to 30 inches,,
if you want a shorter bow,, just make one and learn to shoot it with a shorter draw,,
I find that a bow that will draw 24 inches will shoot pretty hard,, so you could go 48 inches sinew backed and get nice cast at the 24 inches for you brush bow,,,, yes you are right Pat,, with a bit more experience you can get your bows quite a bit shorter than general rule of thumb,, I feel like a good osage stave could go 60 inches bend in handle, 30 inch self bow, and with sinew backing even shorter,,but would take an eye for the stave and some experience making the short bow,, I have seen some guys go way shorter with added deflex etc,, a good rule of thumb that will yield high success, is double the draw plus 10 to 20%,,,we have been debating bout that for at least 30 years so nothing new here,,

[Badger]

  I have taken a few bows in the 64" range rigid handle self bows about 50# and brought them out to 30 or 31 to see if I would get better cast for broadhead flight shooting. They worked out fine but I didn't gain any distance.

[George Tsoukalas]

Depending on the wood, double your draw and add 10-20%. Jawge

[bubby]

I don't think bows need to be anywhere near as long as people are suggesting to reach 30 plus inches but they do need to be over 58".

I realize a bow can be shorter pat but he asked for a rule of thumb and that was what i gave him

[Jim Davis]

Brad and Jawge, you guys have both reported a friendly version of what I have read in several old sources: Twice the draw length plus 15%. The math works out the same, but you guys are more forgiving. 

Jim Davis

[burtonridr]

This one here is a yew short bow, backed with sinew and only 43.5" long,

http://www.primitivearcher.com/smf/index.php/topic,40103.0.html

[loon]

how about
bow 2" at the widest, deflex, short recurve hooks, 53" ntn, little to no overall reflex, draw 30.5"? sinew or... bamboo backed?
 61" D bow with a little asymmetry?

[PatM]

This one here is a yew short bow, backed with sinew and only 43.5" long,

http://www.primitivearcher.com/smf/index.php/topic,40103.0.html

 You missed the draw length. never mind the sinew.