wood arrow spine and foc

[goingoldskool]

After reading several posts about heavy wood arrows and reading Dr Ashby's EFOC, I have a few questions....

1. How do people run 200-300 gr up front without losing spine?

2. My long bow is 53 @ 28 and I draw right under 29....  I've tried running 60# spine with 125gr head and they are very weak....  Looked up the spine calc on 3 rivers and see that for  my cut to center bow, and a 30" arrow, I would need super high spine to run 160+gr heads???

Am I overthinking it????

 I am currently looking into getting a doz woody weights to try with some 70-75# spined surewoods, but not sure if I will drop the spine too much?

Thanks for any info!
Good luck, shoot straight and God Bless,

Rodd

[McDave]

People don't put 200-300 grains up front without losing spine.  Dynamic spine is decreased as weight is added to the front.  If the arrow was in tune before adding the additional weight up front, the only way it can be in tune after adding the weight is to shorten the arrow or get another shaft with higher spine.  Okay, or adding weight to the back, but the EFOC guys would never do that.

It is harder to get EFOC on a 55# bow with wood arrows than with carbon arrows, since a wood shaft with a high enough spine to tune with a heavy tip will be pretty heavy itself, and to get EFOC you ideally need a light shaft and a heavy point.

[Shadowhnter]

With a center cut bow, and 53#.... you will run out of spine most likely before ever reaching very deeply into EFOC. You should be able to get 19%-20% though.

Once you get close to 300gr end, heavier spine needs begin to diminish fairly rapidly as compared to lower weight values.

[goingoldskool]

Thanks guys....

That's kinda what I thought.

[Longtoke]

Some tricks are bumping out your shelf and getting tapered shafts. reducing weight off the back will help your FoC a little, but adding it on  the back will hurt it a lot. the difference between 5/16 nock and 11/32 nock might end up being a couple % in FoC.

[Fletcher]

I've been able to achieve about 21% with woods, but it took lightweight tail tapered Sitka Spruce shafts in 70+ lb spine and 200 gr heads.  Anymore, I shoot tapered Doug Fir With 200 or 235 gr Grizzly Kodiaks or Instincts.  I get shafts on the light side and end up in the 580-600 gr range.  I quit worrying about what the FOC actually is.  These arrows seem to work very well on deer and hogs.

[Elewis]

Might be more messing around then you want to do but I have been adding strike plate thickness to get the arrow away from the center since my arrows were a bit light in spine and couldn't go any shorter.  A cheap and simple way to change the spine requirements of your bow

I would just get some test shafts and some test heads, fletch them up at your proper draw length and see which ones you like.

[SlowBowinMO]

Like carbons, woodies actually take to heavy points very well.  All of my woodies set ups (almost all my bows) are using DF or cedar and 225 to 250 grain points.  Flight and penetration is excellent.

For all that, only one extra spine group is consistently all I need for them to tune properly.

[dnovo]

I made up some cedars for a moose hunt a couple years ago. I'm shooting 53# @ 28" high performance longbow. My cedars were 66-68# spine cut 29 1/2" bop. I put some 190 cutthroats on them with about a 60 grain weight drilled in the shaft. They shoot great. This is the first time I shot them at about 28 yds
 

[goingoldskool]

Looks like I'll wait for the weather to clear up and see what I can do with what I have......doesn't take l I no to heat up a head and change it out!

Thasks for the replies!

Rodd