Since starting my first rod building project a short time ago (thanks to the good folks at Swift Fly Fishing) I’ve learned a number of things I didn’t know about fly rod blanks. One of the more interesting is that within the rod building community there seems to be a serious discussion about utilizing what’s called the “spine” of a rod blank.
Director of Swift, Carl McNeil says that, “Fly rod blanks tend to naturally want to bed more in one direction than the other. This is caused by an effect called the ‘Spine’ and often there is more than one on a blank. The spine is a result of the manufacturing process and is the location of the join or overlap of a graphite or glass flag as it is rolled around the mandrel.” According to the folks at Swift you have four choices of what you can do with the spine and none of them are necessarily right or wrong.
The choices are as follows:
- Place the guides on the inside of the curve – the weaker side. Placing your guides on the inside curve will result in the rod being (moderately) stiffer on the forward cast.
- Place the guides on the outside of the curve – the (marginally) stiffer side. By placing the guides on the outside of the curve you will get (marginally) better lifting power, as you will be pulling against the spine or natural curve of the blank.
- Ignore the spine altogether and align the rod sections so give the straightest most aesthetically pleasing result (our preference). This is what most of the large commercial rod manufactures do.
- Place the guides out at 90 degrees to the spine. Off to the side at right angles to the spine. Don Green, the great rod designer for Fenwick and Sage advocated this method. His reasoning was that the rod should track straight on both backcast as well as forward cast in order to be most accurate. Putting the spine on the top or bottom of the rod means that the rod will tend to kick slightly out of line on either the back or forward cast. By pacing the spine out at 90 degrees the spine is apply the same effect whether on the back or forward cast. (We like this approach too.)
To determine where the spine is on your blank simply follow the directions on this page from Swift Fly Fishing. Or don’t….