Guess my arrows have been underspined?

[mcowie]

I just got a new (to me) longbow.  She's a beauty, great lines, nice color, and a step up in poundage, in short everything I wanted!  

While looking through 3Rivers site I decided that I would order some new shafts and make a new dozen arrows just for her.

I was just about to click the order button when I saw their link to the WoodArrow chart and I figured why not double check the spine.  My arrows are 30" from the knock to the back of the point.  For the past couple of years I have been getting shafts spined 10-15 heaver than my bow to compensate for the longer arrows.  3Rivers chart suggests that I should have been adding 20-25 this whole time.  I don't notice crazy arrow flight but then I fletch with 4 4.5" feathers.

This makes me question whether I know as much as I think I know about arrow spine.  Should I really be getting shafts spined 80-85 for a 67# bow?  I don't see shafts spined that high very often.  Now that I'm questioning myself, what is the effect on arrow spine of pushing a heaver head say in the 160 range?

Thanks for the help.
-Matt

[Tree man]

Matt. I am convinced that many ,many people are shooting  shafts spined too heavy due to basing their choices upon some of those charts. So much depends upon the individual shooter and the degree of centershot built into the bow. I think that you probably have been choosing just right and should ignore the chart if your arrow flight is good.

[JRY309]

I agree with Tree Man there are to many variables with traditional bows to go by spine charts without some testing to your bow.

[aromakr]

Matt:
If your bow is cut less than center and the bow is 67#@28", I would suggest 75/79 spine. If however it is cut too center add one spine range, past center add one or more spine ranges. Once you get past center you can shoot a wide range of spines.
Bob

[mcowie]

Thanks everyone for the help.  

Bob I don't completely understand, are you saying the closer to center cut the bow the greater the arrow spine?  Or do you mean if it's cut to center add one spine range above the bow weight?

Thanks everyone.

[Arco]

Bareshaft it. That tells all...

[Orion]

If your bow is centershot, cut past center, you can overspine by a lot.  If it's cut to center, 5#-10# more will usually work, go heavier if you're going to use a heavier (160 grain) head.  If it's cut 1/8 from center, you'll need to stay closer to the bow's weight.  However, folks usually add 5# of spine for every inch beyond 28 inches of draw,  5# for fast flite strings compared to dacron, 5# for extra heavy heads, i.e., 160 grains and up, etc.  If what you have has been working for you, probably not necessary to change, particularly given that it's going to be hard to find shafts in the 80-85# range.