I used to think that guide spacing was a science known to rod manufactures who designed spacing to fit the performance of their individual rod models. It’s not that complicated. The task is to uniformly locate the guides along the rod without placing a guide on a ferrule. Here’s my logic.

- The first guide (1) is typically 3.5 to 4.5 inches from the tip, and the stripping guide tends to be 28 to 30 inches from the butt. A 7.5 foot rod commonly has 8 guides not counting the tip guide. That makes the stripper number 8.
- I could place a guide every 8 inches between with the first at 4 and the stripper at 60. That would look very odd. It would have guides widely spaced toward the tip where the rod bends the most and narrowly spaced toward the butt where there is little bend. Logically the spacing should increase with each guide from the tip to the butt.
- The distance tip to guide 1 is X, and the space between 1 and 2 is X + an increment (I). Then from 2 to 3 is X + 2I, from 3 to 4 is X + 3I, and so on.
- This leads to the formula: Tip to Guide N is Dn=N*X+I*N*(N-1)/2. I won’t attack you with the formula development, but it comes from the algebra of number series.
- Knowing where the first and last guide will be located allows me to calculate I=(Dn-n*X)/(n*(n-1)/2), where n is the number of guides.

I created a spreadsheet to do the calculations. The inputs are Rod Length, # of Guides, Stripping guide to Butt, Tip to Guide 1, and ferrule locations. The graph shows the results. I had to change the Stripper or First guide location several times to avoid locating a guide on a ferrule.

I also considered the spigot ferrule design. The spigot is glued into the larger section, which makes it very strong. The smaller section slips over the spigot. It needs to be wrapped to reinforce the fiberglass, so I need at least an inch between the ferrule and the guide. Ferrules are at 29.625 and 59.625. For convenience, the spreadsheet rounds the results to eights of an inch.

In the next post I will discuss locating the spline of the rod so that I know which side to place the guides on. After that the actual work of rod building starts.

The spreadsheet is available to you, just click here: Guide Spacing