Rod Blank Spline and Guide Placement
 Rod Blank Spline and Guide Placement
                                                     By: Michael McKeown
As with everything technical, there are many aspects to the decision of where to place the spline, or stiff spot, of a rod blank in relation to the guides. The long held standard is to place the stiff part of the rod such that the fish see it, the back cast sees it, and the forward cast sees the soft part. At about size 9 or 10 weight rods and up, the standard advice has long been to place the stiff part of the rod opposite the fish, so that the fish sees the softer part of the rod.

There's been much written about how to identify the spline, but I'm going to go over it again. The spine, spline, or stiff spot of a blank occurs because of how carbon rods are made. Carbon rods are manufactured by cutting a long, skinny, tapered strip of carbon fiber the length of the rod section. This is wrapped around a tapered steel mandrel. Where the carbon fabric overlaps, the rod is twice as stiff, and creates the spline. To identify which side of the rod is stiff, one can support the blank off the end of a rod wrapping cradle and hang a small weight from the tip. As the rod is rotated, the weight will rise and fall as it sees the stiff and soft parts of the blank. The traditional, easier way, is to place one end of the rod on a smooth surface, bend the rod, and rotate it, feeling for the soft and stiff sections. Sometimes a rod will have two stiff spots. Once the stiff spots are marked, the decision begins.

Placing the stiff part against the fish helps a light rod put it's largest strength against the fish. On very large rods, and very large fish, the narrow stiff spot might rotate strongly in the angler's hands, making it difficult to fight a fish on the narrow stiff section of rod, so larger rods generally put the soft spot towards the fish. On the other hand, placing the stiff spot opposite the fish means the forward cast sees the stiffest spot, and since it's narrow, and the blank likes to pop one way or the other around the stiff spot, such an arrangement can be difficult to cast accurately. On the other other hand, having the stiff section on the forward cast insures the most power possible from the blank can be transmitted to the fly line, making for the longest possible casts from the rod.

On blanks that have two stiff spots, one can put the guides in between them (on one side or the other), or on (or opposite) the stiffer of the two.

Which way is correct? As with most things mechanical, I don't believe there is a right or wrong way, it's just a matter of making one's best choice and seeing how it works. Don't forget, with good tight thread wraps, there's no need to glue them right away, so one could choose to wrap the guides to the blank and try the rod out before gluing them.

There is another decision worthy of attention: single foot or double foot guides. If a given rod with double foot snake guides is fully loaded when aerializing 160 grains of line (as with 60 feet of 5 weight line), and that same rod is changed to single foot guides with 1/2 the thread wraps and 1/2 the glue which means more line can be aerialized in order to still load the rod to it's maximum. This can mean another 10-20 feet of line cast, or 1/6 more water being covered, or allow a heavier line for casting heavier flies with a light enough rod to still be fun on the fish.

As with everything though, there are trade offs. Single foot guides are more likely to be damaged by squashing them. Single foot guides are held to the blank with 1/2 the strength of a double foot guide with wraps at both ends.

The best advice for rod performance is to use single foot guides on smaller rods where the extra attached mass of double foot would slow the action a significant percentage of the total load carrying ability of the rod, and double foot guides where the extra weight is a small percentage of the amount of load capable of the rod, and where the appropriately larger fish for such rods are strong enough to warrant a strong guide to blank connection.�