Arrow spine?/Poor release?

[Bow Bum]

Here's the deal.

I have bare shaft tuned, to the best of my ability to 30 yards. I have some porpoising issues I have not been able to work out with brace, or nock height adjustements.

Can sub-par release cause this? Could arrow spine cause this? I've recently cut the arrows done 1/4", but am suprised they started to porpoise

Perhaps I'm still not spined quite right?

45@28 Kodiak Hunter drawn 29.25"
2117 arrow with 200gr up front cut to 30" BOP

Thansk,

Brian

[Spectre]

Out to 30?? Geez, just fletch'em up!

[Bjorn]

Generally up and down is nock point and side to side is more often  brace or spine. Release can cause either but more often side to side movement. You may also be getting tired if you have been at this for a while. The other element is dropping the bow arm so you can see the arrows flight.
If you have tuned out to 30 yds and bare shafts are grouping with
fletched arrows you may well be ready to go.
I just looked at your signature; are you attempting to tune 2117 to your K Hunter?

[Spectre]

Originally posted by Bjorn:
I just looked at your signature; are you attempting to tune 2117 to your K Hunter?

I was wondering the same thing. You have 2117's bareshafting out to 30?

[Bow Bum]

yup 2117's cut 30" with 200gr up front. Bareshafted to 30. I'm getting porpoising on the fletched shafts. This observation has been over the past week or so. I'm pretty slow to make a change until I'm confident in it. I did move my nock point such that the arrow is level when nocked. It improved flight, and my bareshafts went form low to grouping level. This porpoising thing has me a little baffled right now.

BH's fly right with FP's too, and there is a little less porpoising with them. I think its my form, or release. But I do not have access to a good coach, or shooting guru.

My groups at 30, whe I'm shooting well are pie-plate-ish

[Spectre]

Originally posted by Bow Bum:
yup 2117's cut 30" with 200gr up front. Bareshafted to 30. I'm getting porpoising on the fletched shafts. This observation has been over the past week or so. I'm pretty slow to make a change until I'm confident in it. I did move my nock point such that the arrow is level when nocked. It improved flight, and my bareshafts went form low to grouping level. This porpoising thing has me a little baffled right now.

BH's fly right with FP's too, and there is a little less porpoising with them. I think its my form, or release. But I do not have access to a good coach, or shooting guru.

My groups at 30, whe I'm shooting well are pie-plate-ish

With that, you are killin stuff. Imagine what you would be doing with the proper sized arrow for the bow!

If you are shooting three under that is way to low at the nock, if you are shooting split fingers start at 1/8" up and work up from there.  Sounds like you are doing something to torque things up on release, if the better but still porpoising arrow flight comes from dead level. Could be a twisting off balance finger load on the release or perhaps a dead release that is loosing power which could make your arrows too stiff.

[3undr]

if they fly good at 15yrds fletchem up

[cyred4d]

At 30 yards a lot of things could cause this. How are they grouping at 20 yards?

[Swamp Yankee]

What appears to be porpoising CAN be a spine issue if you cant the bow to any significant degree.

[Bow Bum]

Thanks for the great responses!

I think I'm overspined. I'm just coming out of a shooting funk. Right before it I had shortened my arrow 1/4" thinking I may be a touch under spined... Then things went haywire. I'm getting back into the swing of things and was getting this porpoising issues with my fletched shafts.

I do cant the bow 20-40 degress maybe, and I verified with the Stu Miller calc that I was likely over spined. I had also confirmed that I was about right back before the funk, and shortening the arrows was more of an experiment.

Good thing aluminums are cheap!

Shoot Straight!

Brian

[EHK]

Please keep us posted on this one, Brian.  When I plug your info into Stu's - 30" 2117 with 200 grains up front and a 29" draw on a Kodiak Hunter, it comes out dead on - not overspined.  I've been thinking about trying a similar setup.  I draw 48# at 29.25" on a Grizzly and was looking at a 30.5" 2117 with 145 grains up front.  I was thinking that would be overspined as well, but according to Stu's it's pretty close.  Maybe I'm doing something wrong with the calculator, but I have a keen interest in how things turn out for you.

[Bow Bum]

EHK,

I've been down that road. I had to weigh my nocks and inserts to really get the calculator to work right. (garbage in...garbage out) I draw 29.25" to 29.5" and if I add 1/8" to the arrow It spines correct according to the calculator. Which I believe since at 30.25 I was suspecting to be a little soft.

A couple years ago I had the same bow shooting pretty good with 145gr heads. If memory serves my correct I was right around a 31" shaft. But that was before I knew about the Stu Miller calc. Its been a good reference since.

Your awful close.

Those 2117's will pack a good punch on a bag target to about 20 yards, after that the trajectory is a little tricky.

Good luck!

Brian

[Shawn Leonard]

I still believe they are stiff! Also 3 under nock point should be close 3/4" on that bow. I shoot split and all my bows are tillered for split and my lowest nock point is 5/8th. of an inch. Sorry but an 1/8th. and move form there as mention above for split, just ain't happening. I have very rarley seen a nock point 1/2" let alone an 1/8th. Shawn

Shawn, I nock above the nocking point, on my Super K 3/16" is where it shoots the best with metal arrows. He said his arrow was dead level so 1/8" up is the same as 3/8" when the nock is above the arrow. It does not require changing the nocking point  every shot, just pay attention to where it is and walk up the string, until things start going better. I have seen cases where with new shooters that have their release preassure way off and are releasing weak that the nock seems to be needed to be way higher, but after the form gets stronger and that bow arm gets in a better line a lower nocking point works better. This past summer a fellow was having the same thing, when I watched him shoot I noticed that he was pulling the string with his index finger and hardly any pull coming from his bottom fingers,to compensate was twisting with his drawing hand and having finger pinch pain on his index finger.  He was convinced that his nock needed to go lower, nearly dead level. Balancing out the power line and getting him to use those bottom fingers ended up with the nock about 1/4" up, bottom nocking point.