Fly fishing questions, flies, fish weight formula, salmon.

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Fly fishing questions page 1.

Questions can be about any aspect of fly fishing, fly casting, casting instruction, fishing in Scotland or abroad, fly fishing courses, fishing flies, etc. The following is just a random selection of questions that have been send by readers and answered by Ally. If you have a question that you wish to ask please do not hesitate to complete the form.

Questions:

Cracking tube flies
Fish weight formula
Spey casting problem
Custom fly lines
Tube fly information
Salmon and steelhead fishing in cold water
Spey cast inswing

Cracking tube flies
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Question:

Last season I began using 3/4 inch aluminium tubes (purchased, not home made.) I hooked more fish than in a normal year so I continued to use them. The problem is that I am losing the tube after about an hours casting, on two occasions last season I actually unfortunately broke in the fish when tightening into them. At first I thought I may have been cracking them off on the back cast, but I always wait to feel the fly straighten out before the forward cast. On one occasion this week I lost the tube to find that the cast was badly frayed and the tube again gone. Last season I was using Maxima 12lb. breaking strain and this season I have started to use Tynex 12lb but the problem still persists. After all my fly fishing experience it is so frustrating, on normal flies I don't have a problem, even when I have fished Waddingtons in the past this has never happened.

Answer:

There are various reasons for snapping off flies during casting, the first of which is bad timing. In this case that does not appear to be the problem and the reason could be simpler, perhaps there are sharp edges on the tube fly itself and the movement induced by casting is abrading the leader. It is important to ensure that all tube flies are lined with polyethylene or a like material. Using leader that is too light or too soft or too long would exacerbate the problem but you have taken care of that aspect. Normally I use a minimum diameter of 0.35mm leader of overall length less than 8 feet for spring size tube flies.

Fish weight formula
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Question:

I just got back from a trip to the Sustut River in BC. The subject of calculating the weight of a fish came up. In camp they were using a formula 1.33 x length in inches x girth in inches x girth in inches divided by 800 to give the wt in lbs. The weights didn't look quite right to me, so I looked it up on the internet. Many sites give a formula of length x girth x girth which seems way off. At least compared to the length minus 20 rule which I have used in the past. I would be interested to know the formulas used on your web site since all of them give a calculation which at least appears closer to what I would have estimated.

Answer: All fish are not built the same way, some are fat and some are slim. To take account of this several volumetric based formulae have been developed over the years. Girth is measured at the anterior (front) edge of the dorsal fin. "The Fisherman's Vade Mecum" by G W Maunsell contains a formula to derive weight from length and girth measurements.

Weight (lbs) = (4/3 x L) x Gˆ2/1000 (L & G in inches)

Thanks to Dr Andrew Gowans's research data from the Tay I obtained measurements and weights from 875 fresh Tay salmon and was able to test the accuracy this formula. Generally speaking the weights were underestimated by it and so we produced a new formula statistically corrected to minimise the error. Probably the difference arises because the old formula was based on fish that had been dead for a time or were not exactly fresh run. After death fish can loose weight at a rate of 2% per six hours. More than 80% of fish weights are predicted within 5% of the actual weight of the fish by the new formula.

Gowans formula Weight (Kg) = 41.4 x L x Gˆ2 (L & G in metres).

To save calculating weight from this formula, you can enter the length and girth in the Fish o'meter on this site and it will do the hard work for you.

Spey casting problem
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Question:

I have a problem with my single Spey cast. On the forward cast the last part of the loop collides with the body of the fly line and kills the cast. Up until that point all appears to be going well, the loop forms well above the water and the line shoots out nicely. Thank you in advance.

Answer: Presumably you mean that the end of the line or the leader tangles as the line straightens - like a tailing loop on an overhead cast? I can think of a couple of things that might cause that. The first is that the forward cast is being made at a "closing" angle to the D loop. I which case make sure that you place the anchor and the D loop parallel to the direction of the intended forward cast or to test the theory make the slightly more downstream to open the loop. The other less likely cause is that you are making the forward cast too sharply. A Spey cast is like every other cast, the longer and smoother you can make that final acceleration to a positive stop the straighter the outgoing loop will be.

Custom fly lines
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Question:

I have 2 questions about fishing 45' of sinking line attached to running line.

1. I was taught to mend the sinking portion (tip/leader) parallel to the current, allow it to sink, then fish out the cast. Usually this means casting at 90 degrees to the current, putting a big mend in, to position the sinking portion & mending the floating portion as necessary to delay the swing until the line has sunk & is now down at about 45 degrees. With 45' of sinking line + running line, mending would appear difficult. Do you aim for a 45 degree cast with a straight line & just let it fish?

2. Where do you find 45' of sinking line? Are full sinking DT or level lines still available in GB, so you can cut them up to make such a line? 30' heads are about it here.

Answer: With a custom made sinking line as discussed you can make the cast and keep the rod tip high to allow more line to be fed out to get the sinking line down to a suitable depth. You may also walk downstream for a couple of paces to achieve slack for that purpose.

Full length sinking lines are certainly available in the UK and many of them come from the USA so it should be possible to obtain them in USA. Cortland and Scientific Anglers certainly make them.

Tube fly information
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Question:

Ally, It's pretty hard on this side of the pond to get any information (patterns etc.) on tube flies. Are there any books or videos on the subject available in the UK?

Answer: Books on tube flies! Japanese writer Ken Sawada has an excellent book called Tube and Waddington Fly Dressing but I hardly think that you'll need a book for tubes. What size and weights of tubes do you want to make? We make them from Polyethylene tube sometimes over sleeved with aluminium, brass or copper for weight. Non sterile PORTEX tube can be bought for surgical suppliers (or scrounged from a doctor). The best stuff stretches to a smaller diameter when pulled and turns over at the ends when gently heated with a lighter. So you can line metal tube bought from the model shop once its cut to length. Loop tackle do a series of wine bottle shaped heavy brass tubes for tying the temple dog types with arctic fox hair. We usually use bucktail for winging and it's usually tied all round. The best way to hold the hook in place on big tubes is with Hellerman Sleeves - used in the electronics industry to protect wires I believe. They are real rubber and can stand the cold water. Silicon rubber (usually sold for the job) is useless. To fix the tube to the vice use a darning needle of the correct diameter and shove the tube onto it.

Salmon and steelhead fishing in cold water
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Question:

For cold water/winter fishing what line system have you found to be the best with the Spey rod? I have been using sinking leaders, weighted flies & tips in various lengths looped to the front of a floating line. They all seem to work reasonably well, but I'm never quite sure which is fishing most efficiently. The tips seem to be the most work to cast, but I'm not completely convinced that they are doing a better job than the leaders. I'd be very interested in your experiences.

Answer: I use a comfortable length of sinking line attached to a floating running line or mono shooting line. Normally that means at least 3 feet of line per foot of rod length. With this I can cast much more easily. Sinking tips work better on the end of intermediate or sink tip lines than they do on floaters anyway but a floating line has the advantage of drifting round the swing faster - something that is useful on some pools. I use all weights of flies. In slow currents there may be an advantage in using a light plastic tube fly with a sinking line because it hovers and moves better in the soft flows. For Atlantic salmon the rule of thumb is that we fish deep until about 48 deg F. In practice it also depends on the strength of flow and I would not hesitate to fish a fast sinking line to reach them at any temperature. We don't have the high temperature differentials between air and water that you might have and a sink tip or intermediate line will work here until the fly catches bottom! In fact it's almost a case of considering when we would risk using a floater! Heavy flies are not the easiest to deal with on a floating line - you may have noticed. With a short strong leader and a sinking line the balance is much better.

Spey cast inswing
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Question:

Why exactly do you drift the rod and line to the inside on the Single Spey (from the left bank water going right to left) then back outside before turning and casting back out to the river.

Answer:

To produce a controlled belly of line in the air that will suddenly flip from the inside (as you made it) to the outside and carry the whole belly that forms the D loop with it cleanly upstream. You can make the cast without it, but its harder to turn the D loop efficiently. In bad cases the line may come across your body rather than go out and round upstream.

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Copyright 2007 Alastair Gowans AAPGAI and FFF Master and THCI, APGAI. All rights reserved.