So my local guru says he thinks I should use a 5" Feather on my next set of arrows. Don`t know if draw weight or draw length matters,but it`s a 45lb Savannah. What differences are there from 4-5inch feathers,if any?

If properly tuned, 4" is plenty in all circumstances.

It just comes down to personal preference.

Both 4" and 5" work, but I like 5" for big broadheads on heavy arrow setups.

QuoteOriginally posted by Night Wing:
It just comes down to personal preference.

Both 4" and 5" work, but I like 5" for big broadheads on heavy arrow setups.

how big is a big broadhead?

It's all about keeping the sharp end flying true. If you can do that with 4" great. If not use 5".

I like a 5 inch when I'm using snuffers, or 4 fletch 4inchers. I use 3 fletch 4" now that I'm shooting mostly grizzlies.

I've found that a 4 inch feather is plenty when using a 2 blade broadhead, but that when I use a 3 blade broadhead I get better flight with 5 inch.

I have gone to all 4 inch after years of 5 inchers, and I don't notice any real difference.

I agree with most of the others. Tuned arrows and a consistant release are the key. If you need 5", use them.  4" has been plenty for me.  All things being equal, you will have faster arrow flight, quieter flight, and less arrow deflection in a strong cross wind with the 4" feathers.