arrow spine?

Ok so i am new to archery but i am doing my best to learn quickly. I shoot a Martin Savannah 45# and I am curious if anyone has a good starting point for arrow spine using cedar. Any advice would be great.

arrow spine

That goes back a ways, can't remember much about that. I shot what was called forgewoods (compressed shafts) back in stickbow days. They were heavy but great for close shots. Hilbre heads and great penetration. Then we went to fiberglass, then aluminum 312 magnums for 55#'s.
I shot cedar for years, but can't remember how they got a matched dozen. Barred turkey feathers were the best.

As a general rule you would want 45-50# spined shafts if you are shooting a dacron string. If you are using Fast-Flite string materials up it by 10 pounds to 55-60# shafts. Even so, there are other factors that might be considered such as your draw length, broad head weight, fletchings, etc.. I have found I am doing well to get 8 out of a dozen ordered arrows to fly really good out of any particular bow I ordered them for. I have also found that my bows may shoot varying spine weights with differences of +or - 10 pounds of spine weight very well. For example, I have a 65# longbow with FF string that will shoot some of my 65-70 spined shafts well as well as 70-75 spines. I test shoot my arrows that have hunting heads on and often end up carrying different spine weights because they end up in the batch that fly good from the bow I will be hunting with.
As if this were not enough to have to consider there are tapered shafts that can make a world of difference regarding what spine weights you find shoot well out of your bow. Personally, I love the rear tapered shafts and I have found I can stay in the 65-70 spines with the tapered shafts from my 65# bow and they fly much better than my barrel shafts.

Hope this helps more than confuses you.