I find that a WF6# line casts nicely on my Guideline LPXe 6# rod, however use a DT6# and it all turns to rubbish, with tailing casts and a heap of line in front of me,u nless I am extra careful, now started using a DT5# line on the same rod and all is fine.
This is the case on my Orvis Western2 as well, you hear all the time about this line difference on rods, so is it a rule of thumb, or should manufactures re calibrate their DT lines.

When you start extending a DT beyond 30' you effectivly start going up 1 weight every 6' (I think) so if you were airealising 42' you would be using an 8# line.
But using the 5# with 42' you would be on a 7# equivellent.
But when using the WF you will be shooting the line at the back of the head(at the running line),so you will be getting a 6# every time.
Or so the theory goes.

Jim

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The Fishermans Friend is the Flirty Fly,Fickle Food for Fleeting Fish.

This is simply down to the weight of line you are casting with.
The AFTM rating is the weight of the first 35ft of line. So, with a WF line, the first 35ft weigh up to #6. After this length, you are then down to the thin running line which weighs very little, so even if this is outside of the rod tip it will not make much difference to the weight of line you are trying to cast.
A double taper is also made so that the first 35ft is #6, however, the line after this does not become thin running line, it stays as thick fly line.
So, if you allow more than 35ft of line out of the rod tip, it will weigh more than #6 and over load the rod.
This is probably causing the tailing loops as the rod bends too far during the middle of the cast, causing the rod tip to move in an arc raher than a straight line.

This does not happen when you use a #5 DT line on a #6 rod as the extra weight of line outside the rod tip is probably making the line actually weigh the same as a #6 WF.

One easy way around this is to measure out 35ft of your DT line and then mark it with a permanent marker. When you are casting, make sure that this marker does not stray outside of the rod tip.

---------- Post added at 04:36 PM ---------- Previous post was at 04:31 PM ----------

Just saw 3lbgraylings post, he says 30ft, I said 35ft .... I'd hate to be wrong and have you drawing lines on the wrong bit of line, so advise you check it out first !!

I thought it was 10 yards, whats that in feet?..... 30

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Time is a stream I go fishing in.

Sorry, I'm not including the front taper.

Jim

__________________
The Fishermans Friend is the Flirty Fly,Fickle Food for Fleeting Fish.

Ever the politician Jim!

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http://www.flyfishinglessons.co.uk
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Even with an overloaded rod you shouldn't really be tailing - this suggests your power application may have issues or you haven't widened your casting arc sufficiently to maintain SLP with the increased load (it could of course be something else!).

Thanks for the posts, that does explain it , every one basically singing from the same sheet so to speak.
Re the tailing issues, I am working on that to sort it, I don't seem to tail as much with a WF line, just got to keep practising. Re the weight of line thing, I recently made up a shooting head from an old 8# sinker for bass fishing, I weighed the first 35 feet of theDT6# on a set of very accurate scales, then cut the 8# line to the same weight, and hey presto a really nice to cast shooting head.