I am experimenting with FOC and would like to know if nyone can help with a formula to spine timber shafts as I have some woody weights (test kit) coming from 3 rivers so how many pounds do I add to the shaft for every inch over 28" and every grain added to the front. I am shooting 65 pound recurve at 29" and 31" arrows 190gn field point and looking at putting a 150gn woody weight on maybe? depends on testing

Cheers

Mark I found that if I add about 100gr up front I need to go up about 10 lbs in spine. I hope this helps.
Jack

bowshu you answered your question in the last part of your post "depends on testing".  

So you're drawing 65# at 29" & shooting 340 grains total BH weight, from a 31" shaft, yes?

Any idea as to the degree of centre-cut on your bow, in fractions of an inch?

"Any idea as to the degree of centre-cut on your bow, in fractions of an inch?"

That would help!

Sounds like you're adding 340 gr. of point weight, right?

You might want to start looking for some bamboo arrows. ART

Wood just isn't available in spines as stiff as carbon, and that limitation also limits the amount they can be front loaded.  With 340 grains up front and drawing 65#@29, you would need at least 90# in a softwood shaft like cedar or spruce, and 100# would likely be better.  In hardwoods like hickory, ash, etc., which don't recover as fast, a spine well over 100# would be needed.  Spines this high are very hard to come by.  Good luck.

Thanks for your help everyone will find out how they go in 2-3 weeks when the gear turns up:thumbsup:  and I will keep you posted on the results

Cheers Bowshu