Arrow spine

[aussiehunter]

Trads, If you slide a weight tube down an arrow shaft to increase the weight of the arrow, would that increase the spine of the shaft (stiffer)?

John

[JRY309]

I have used weight tubes and didn't notice a spine change,but some say they have.Weight tubes add weight over the entire length of the shaft.I have only used the 3 gpi tubes,but I've heard the heavier 8 gpi tubes affected spine.One thing too about weight tubes is if you hit a hard object they will pop out the nock.

[metsastaja]

just a little bit.

[jbuck9]

I do not use weight tubes, but I read several posts that fellas said they weaken there shaft, which I could'int understand, do a search on weight tubes.

[Old York]

I don't think it should change the
static spine, if the tubing itself
is reasonably flexible. Dynamic spine would
increase (behave stiffer) because of the
added overall weight, yes? No?

[Orion]

I think making the shaft  heavier decreases the static spine, all other things being equal.  If same weight bow is pushing the arrow, the arrow, because of its increased mass, will bend more before the energy applied to it will move it forward. If I remember the principle correctly, it's "Any object at rest tends to stay at rest."  So a heavier object either takes more energy to move, or takes longer to move with the same amount of energy.  In the latter case it must bend more before the energy applied to it starts it moving, thus a decrease in dynamic spine. Yes/No?  Regardless, the difference is probably quite small.

[aussiehunter]

Trads, I have done a quick search on the net as suggested and this is what I found:

Carbon Arrow Dilemma  
I have a 1998 Golden Eagle Evolution, which I enjoy very much. But I shoot a lot of 3-D. I have a target in my backyard I shoot every day, and I go to the local 3-D range every week. I shoot aluminum arrows (2315, 28 inches long, with 125-grain tips, 5-inch plastic vanes, and I use a release), but I end up bending some arrows. I own an arrow straightener but I am not very good with it.  
What I would like to know is what if any carbon arrow will weigh close to the weight of my aluminum arrows. The reason being, I have tried some carbon arrows and even with Sims LimbSavers and string leeches, my bow is louder with carbon arrows. So could you tell me what would be the heaviest carbon arrow spined for my bow (I shoot 65 pounds)? And what about these carbon arrows that I've heard about that you slide plastic tubes in them?  
Robert A. Brown Jr.
Shelby, Michigan  

Norb's Answer:  I judge that you are aware that, with all else being equal, in order to maintain the same noise level with your bow you will have to shoot arrows close to the same weight as your present arrows.  
I estimate that your 2315 arrows weigh approximately 520 grains. The Game Tracker Terminator Hunter 6075 (T 2003 shaft) weighs 12 grains per inch. A complete 28-inch arrow with three five-inch vane fletch should come close to equaling that weight with a 125-grain point.  
Game Tracker also offers plastic weight tubes for insertion in arrow shafts to add weight and increase kinetic energy. Red tubes weigh two grains per inch. Yellow tubes weigh three grains per inch. These weight tubes have little effect on the static spine but do reduce dynamic spine.  

This statement was written by Norb Mullaney Director of Bow Testing for Archery World Magazine and subsequently for Bowhunting World Magazine. Norb Mullaney has been shooting bows and arrows of one type or another for over 70 years. He started with a hickory self bow at 8 or 9 years of age, progressed through self longbows, a solid fiberglass bow, several commercial laminated recurves, recurves of his own design and building.

Hope this info helps us all.
John