shock/casting dimple - Spey Pages
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post #1 of 3 (permalink) Old 04-08-2000, 07:36 PM Thread Starter
Join Date: Feb 2002
Posts: 3,411
Originator: AndreDate: 4/8/2000 3:36 PM

What is/are the causes of shock dimples?

As I seam to work a longer line I seam to increase the size of the dimple. While fishing the Skagit last week and working a long line (for me 80-90 including tip), as I lengthen working line the size of the dimple seamed to increase. I got the impression that I was over powering the casts caused by too large an anchor. Casts at 80' arent bad add the extra 10 without shooting and it became another store.


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post #2 of 3 (permalink) Old 04-09-2000, 11:20 AM Thread Starter
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Originator: bubbaDate: 4/9/2000 7:20 AM
hi andre

there are several causes of a shock dimple, which is a normal finding in spey casts, due to the reltaive "slowness" of the rods used. the downward deflection of the rod tip at the end of the forward cast causes the shock dimple; in essence some of the energy of the forward stroke is lost by the rod tip deflecting donward, instead of forward only. the stiffer the tip of the rod, usually the lower the "kick-point" in the rod (the section of the rod that flexes the most during casting). i have studied slow motion and stop motion video of several rods of different actions casting the same line by the same expert caster. the faster action rods with higher kick points cast a smaller shock dimple than slower rods with stiffer tips. two excellent examples are the thomas and thomas 10 weight/15' (representing a fast rod), and the older (pre-1998) scott arc 10 weight 15' foot rod (representing the slower rod). both are capable of easily casting more than 100 feet, with tips, but the line going out looks quite different. both will "break down" beyond a certain distance (even when using the exact same line), for different reasons. the T & T breaks down because the tip is not very stiff, and it essentially has a nervous breakdown when asked to do too much; you end up casting the equivalent of a 13' rod. the harder you hit it, the less return you get beyond a certain point. the older arc (scott) breaks down because at the kick point, the rod "folds over" when hit really hard, and the shock dimple becomes so big, it throws a part of the forward cast into the water, limiting the ultimate distance portential of the rod and line. within normal fishing distances (75-90 feet), both rods work just fine... it becomes a matter of taste really, and the type of line you line to throw. i would venture, from my experience, that the faster rods favor casters who finish high on the forward power stroke, prefer to cast shooting taper type lines (e.g. windcutter) with brief, or abbreviated strokes, or like casting long bellied lines with tighter loops. the older scott arc series is a more versatile and forgiving rod, but perhaps a little more difficult in the wind (due to the looser loop and larger shock dimple).

timing is also a critical component on how large the shock dimple will be; if you hit your forward cast too early or too late, the shock dimple will be accentuated, because there is less tension in the line, and the downward deflection of the rod tip at the end of the power stroke will be more readily manifest as a downward deflection in the line (i.e. shock dimple).

another cause of a large shock dimple is "hinging" about the upper hand, letting the bottom hand get out too far in front of the chest. this promotes a more arc-like forward stroke, driving, then accentuating the rod tips downward deflection at the conclusion of the forward power stroke.

to minimize you shock dimple, "hit" the forward power stroke only as hard as it needs to be hit in order to get the line to lay out all the way. with the slower action rods, be patient, and perfect your timing, letting the rod load and unload, doing your work for you. (like downhill skiing, the good skier lets the skis do all the work turning, instead of horsing them around like the intermediate skier). experiment with how much "wrist flick" you need at the end of the cast, especially with slower rods. with longer casts (>100 feet) you will probably need to drop the upper hand closer to the reel, and raise both hands during the forward cast; your bottom hand may be under your chin. start high, adn end high. this essentially adds a foot of rod length.

good luck‚Äď
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post #3 of 3 (permalink) Old 04-10-2000, 01:27 PM Thread Starter
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Originator: DanaDate: 4/10/2000 9:27 AM

I can't add too much to bubba's excellent post, but I wanted to highlight the issue of matching the "correct" line to the rod.

Here in BC conventional wisdom has it that the Sage 9140-4 should be matched with the SA 10/11 Mastery/Spey. As you work out line with this combination, the "shock dimple" (I've also heard it referred to as the "tank track") and other effects become more pronounced for most casters. Recently we have started to use the SA 8/9 Mastery/Spey and a customized version of this line with this rod, and things have improved. The rod takes on a "crisper" feel and, when changing a wide angle of direction, is less prone to throwing the line into itself on the forward delivery.

Since there is no apparent industry standard as to how a Spey rod line weight is designated (or even how a "Spey line" is to be designed, for that matter), it is likely that some of the effects that we observe could be the result of the unintentional overlining of a rod. It would be very useful for manufacturers to let us know which line(s) were used in the rod design process as we would then be able to better match the line to the rod. In the case of the rod above, it is designated as a 9/10; the Mastery 10/11 that I have tested has a belly section that is closer to a  DT 12 than 11; the 8/9 mics out to @ DT 10. So, even though the lines are rated as 10/11 or 8/9, the 50' of level belly section that makes up the bulk of the weight of the line is "heavier" than the manufacturer's line rating (note: I am not using a digital scale here, but measuring the line diameter using a micrometer or thickness gage--perhaps not the most accurate approach, but sufficient for my purposes so far. When making the comparisions I am using SA products: the Mastery Spey lines and the Ultra 3 120' Salmon Tapers, and I am presuming that both lines are constructed of similar materials. For more detailed info about the variance in Spey line design and construction, click on the link to Ally Gowans' site on the home page for an article about Spey lines and how different similarly-rated lines really are). Knowing how different these lines are, it is not surprising then that the 9140-4 seems to like to throw the 8/9 (essentially a 10 weight line) better than the 10/11 (closer to a 12 weight line).

Every rod will have a "sweet spot" for every line that you match it with, the point at which it best handles that line. As you lengthen line, additional load is placed upon the rod, and, as bubba states, depending on the design of the rod and the weight and balance of the line, the rod eventually begins to fold up. If the tip is too light or heavy you will end up with the effects bubba describes. If  a rod "locks" and will no longer flex at a certain point as the load progresses down the blank, you get the breakage that we have seen with the Sage 10151-4 [of course, there are a bizillion other design factors that will influence how a rod behaves, including the individual casting style(s) of the rod designers and testers].

If the rod or line is behaving oddly while casting, and you have determined that your casting technique is not at fault, try switching lines; alternatively, get out the micrometer, scissors and glue and, after you find that sweet match between rod and line-length, cut out the remaining portion of the belly and re-splice your main line to the running line.

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