New Member / Spine Question

[bruce.net]

Greetings all.  I have been lurking the past few months since my introduction to this great sport and finally registered.  A lot of great information here and I have very much enjoyed going through the posts due to the wealth of information.

I was fortunate to get a Maddog Prairie Predator a few months back from someone who had stopped hunting.  I instantly fell in love the the feeling of shooting the long bow after having a warf recurve for a few month prior to that.  So obviously I am still working through my form / techniques hoping that next season I will be in a position to start hunting with some friends in NE Ohio.

I have been interested in making my own wood arrows and I am a little stuck with the process.  My 41# marked bow measures out around 44# on my DIY draw board at 29", which is my draw length.  Based on the various spine charts I should be in the 55 - 60 spine range for a 31" arrow with a 125g tip.  Bare shafting and trying to be very careful with my form I am still very much nock left.  So going up to a 63 spine (as tested on my DIY spine tester) I am finally getting a straight arrow at close distance, but the arrow length is down to 30 5/8".  So I am thinking I need 65 - 70 spine shafts so the arrow is long enough for eventual broad heads. 

Is this normal to be so far "off the charts"?  I know my technique is not always perfect, but I can consistently get five of six arrows into a softball size group at 15 yards.

Any insight would be appreciated.

Thank you.

Bruce

[McDave]

Bare shafting is what it is, with a couple of exceptions.

You have to be sure that your weak indication is a true weak and not a false weak.  A false weak indication happens when the bare shaft is really too stiff, and rebounds off the strike plate nock left.  You should see consistent improvements in nock left as you increase in spine if the spine is truly weak.  I would be interested in seeing what happens if you put a 200 grain point on your 55-60# bare shaft.  Does the weak indication get worse or better?

How is your nock high coming along?  I have found at times that nock high and nock right-left are related.  They write about them as if they were two separate problems to solve, but I think they are more accurately described as parts of the same problem.

When you get close to the bare shaft flight you want, leave it a little weak, because adding fletches stiffens the arrow some.

I don't know where the shelf on the longbow you have is cut with respect to center.  If it is not cut to center, or not cut past center, it will require a weaker arrow than if it were cut past center.  I would be surprised if a 44# longbow not cut past center would require a 65-70# spine arrow.

[slowbowjoe]

First impression: If your arrows are 31" to back of point, that's 3" longer than the standard spend length of 28". Each inch of arrow length over 28 effectively reduces dynamic spine by 5#, so the DYNAMIC spine of 55-60's becomes 40-45# with 125 points. So yes, that length arrow might call for moving up a spine group.

'Course there's a few more variables (string type, center cut or not, etc). One of the reasons I'm so partial to wood is tuning gets relatively simple using rule of thumb figuring, which has worked better for me than "the calculator". As for spine charts, have a look at  "arrowskp.com" (NOTE: Kelly's not competing with any sponsors here, it's just a reference for his wealth of experience). Simple, and as accurate, or more so, than than more complicated charts.

[bruce.net]

Thank you very much for the responses.  I am going to keep trying as see how it all shakes out.

Bruce

[NY Yankee]

Yes, the charts aren't the final word on spine, just a starting place. There are so many variables involved in dynamic spine you just have to shoot it to see what your bow likes. It's not uncommon to be 20-25 pounds more than the charts say, especially with a center-cut bow. With a heavy draw weight, wood shaft, and a heavy point, I have had some really heavy spine arrows, over 100 pounds with a 70 pound bow and 200 gr head and long draw length. Keep shooting and keep notes on each arrow. Doesn't hurt to write specs on the arrows 'til you get it dialed in.

[durp]

are u measuring the shaft to the back of point or ? ...u said ur shaft are now 30 5/8 and u have a 29 inch draw

u have plenty of shaft for broad heads IF ur are measuring to back of point

[Wheels2]

I recently bought a Covert Hunter.  They are know to be high performance.  It draws 50# @ 28".  Original owner shot 95#-100# woods, 30", with 145 grain tips

So my point being that bow performance means a lot.

[bruce.net]

Thanks again for all the replies and suggestions.

The last arrow I tried was a 63# shaft, 30 5/8 to the front taper.  So using a back of point it was closer to 30 1/4.

I hope to have more time this weekend to keep trying.  I have the point test kit so I can adjust points but only up to 160. 

Thanks again!

[Wheels2]

When you shoot bare shaft, wrap tape around the shaft in the area of the fletching in an amount equal to the weight of the fletching you use.  5" feathers run about 18 grains.
Otherwise it is like shooting a point that is 18 grains lighter than it weighs.

I shoot bare shafts a lot.  They show you all of your shooting flaws and issues beyond tuning.  If you can get a bare shat to fly straight and true out to 25 or 30 yards, there will not be any issues with broadheads.

A good tune allows you to go to smaller fletching and that adds a touch more speed at farther distances for better momentum and flatter trajectory.