Arrow length? Need some help...

[joaxe]

Larry,

I just bought some new arrows to use this season. I'm about to cut them and install inserts but I have a question.

I have the OnTarget 2 software (SFA), ran the numbers and came up with an arrow length that seems to work with my setup. Can you run the same numbers and let me know if I'm on the right track?

My setup:

2006 Switchback XT @ 28" DL - 80% LO
63 lbs.
String Splitter peep - 22 grains
D-Loop - 8 grains
Kisser button - 6 grains
2" Blazer vanes - 5 grains each
Points used - 100 grains

I've bought CE Terminator Lite Hunter WF arrows (4560). I had previously used CE Eliminator 250 arrows cut at 27.5" (not by me). If I'm using OT2 right, I should be able to go with 30" arrows with the CE Terminator Lite Hunters. This appears to let me adjust DW between 62 and 66lbs (I'm still working up to 70!)

Can you confirm or deny these numbers? I know if I bump up to 125 grain points, a shorter arrow looks like it will work. I'm just concerned that 30" is too long. I would also have to buy all new broadheads!

Need some help....afraid that the saw will have a mind of its own!

Thanks in advance!

Joe

[PSI]

Joe,

It looks as though the CE Eliminator 250 arrows cut at 27.5" would work (0.415 spine). You should try paper tuning to see if they''ll be OK.

The CE Terminator Lite Hunters should also work (0.398 spine)...especially if you are adding draw weight later.

You might want to measure the draw length on your SB...most of the Mathews I've owned have run long..up to 0.5". If the bow is really 28.5", you should be fine with a shaft length ~28.0" to 28.5" from ~64-69lbs DW.


A couple things to remember...

The spine calculation is designed to give different results for hunting and target usage given the same setup. Based on the theory that it's better to have the shaft spine be a little stiffer when using broadheads. Make sure to use the "Hunting" filter.

The spine selection process used by OnTarget Software For Archers (SFA) or Shaft Selector (SS) is a custom algorithm, not chart based. It imposes a default maximum "Sensitivity" span of 0.025 (adjustable from 0.015 to 0.035). On the Spine Match tab , the entire "green" area of the "weak/good/stiff" color gradient scale equals the Sensitivity value. Each "tick mark" above the color gradient scale represents one half the Sensitivity value or, at the default setting, 0.0125 in spine.

If you examine the Easton charts, the recommendations made in a given chart "group" cell range from a span of 0.193 to 0.005 in static spine. A commonly used cell, the T11...hard cam, 65-70lbs DW, w/28" arrow...recommends shafts with static spines from 0.400 to 0.340.

The average spine spread for the T1-T14 cells is 0.101.

Assuming a 0.140 span like the T11 cell mentioned above, you could have an "Optimal Spine" of plus/minus 0.070 on the "weak/good/stiff" scale, or about 5-6 tick marks from "dead center green". If you assume a wide 0.140 span is "OK", then the scale pointer in SFA and SS could be almost into the "orange-red" weak/stiff and still be "acceptable".