But, but, butt...

[Mangrove Cuckoo]

Does anyone know what the specific density of an intermediate saltwater line is?

The specific density of nylon monofilament is around 1.15, while the sd of fluorocarbon is somewhere near 1.75.

Bruce Richard's recent article in the Loop suggests matching the nylon monofilament butt section to a floating flyline by applying a factor of 0.7 to the diameter of the tip of the flyline. Which I infer to mean he suspects the specific density of the flyline to be somewhere around 0.8. It has to be less than 1 or it would not float. If you divide 0.8 by 1.15 you get approximately 0.7.

What Bruce does not address is what the leader butt diameter should be if you were to use fluorocarbon leader material. If you were to use fluoro on a floating line, then by using the above rationale, the diameter of the butt should be somewhere near 0.8 / 1.75 or 0.45% of the flyline tip diameter.

Why might you do such a thing? Maybe to fish as deep as possible while still using a floating flyline… and hoping to get the best (smoothest) transfer of energy through the flyline into the leader and hence a more elegant turnover of the fly.

OK then, what if you are going to use, say, an intermediate tip flyline, but you still want to get as smooth a turnover as possible? In that case, the specific gravity of the flyline is greater than one. But, how much greater than one is hard (for me) to determine. I'm not going to cut off a foot and weigh it. The only data I could find on-line was that an old fashioned Cortland intermediate line had a specific density of 1.05. So, if you take a wild guess and use 1.1 for the sd of an imaginary intermediate flyline, then the ratio of fluorocarbon tippet diameter to the flyline would be somewhere around 1.1/ 1.75 or we are now around 0.63 as a multiplication factor.

Does that make sense to y'all?

Thanks.

[VGB]

https://www.sexyloops.com/index.php/ps/i-am-being-dense

[Paul Arden]

Hi Gary,

I’ve emailed Bruce. Thought that would be easiest

Cheers, Paul

[Viking Lars]

Where can I find this article?

Lars

[Mangrove Cuckoo]

Lars,

Bruce's article is in the recent "Loop" on the FFi website.

BTW... I believe I may have shown my age by using the term "specific density". That apparently is old school. The more proper term these days appears to be "specific gravity".

Another curiosity has shown up: when measuring the tips of a handful of my most recent flylines, I found that the diameters of the supposed short level tips are not level. All of these lines have the welded loop built in, so I did not measure at that point. But what was curious is that all the lines had thicker diameters close to that welded loop, which then tapered thinner as I moved back up the line. The "tips" were usually only 1 foot in length, or less, before the front taper of the flyline began to show.

I guess it is not unexpected that the welded loops will be heavier than the tip, but the thicker diameter also might make a small but maybe appreciable impact too. So... are the manufacturers deliberately making weight forward tips on their weight forward lines?

[Paul Arden]

Bruce hasn’t logged in for a while and I’ll reset his password but he sent this reply…

Hi Gary,
SW floating lines have densities of around .90 so to match a nylon leader butt to them the diameter of the butt should be about 75% of the diameter of the line tip. That is to insure the most effective energy transfer, of course. And you’re right, if using fluorocarbon leaders, which are much denser, the butts should be about 50% to match. But I’ve never seen a reason to use a fluorocarbon leader. Adding a fluorocarbon tippet to a nylon leader makes more sense to me.
“Intermediate” lines are denser than floaters, obviously. The exact density varies but most are about the same density as nylon so to perfectly mass match leader butts to line tips they would need to be the same size. That is a very large leader butt. But remember that the goal of a perfect mass match is to have the best energy transfer for the smoothest turnover. Do we always need that? No. It is most important with light floating lines and usually when dry fly fishing for trout. Mismatching can disrupt how the line/leader turn over and deliver which can affect accuracy. For most other applications it isn’t as important so there is more leeway. Most sinking lines are fished with leader butts that are smaller than ideal, but readily available to buy and work well enough.
For faster sinking lines that are more dense than intermediates leader butts would have to be much bigger than line tips. No one does that. But of course, we don’t expect the same elegant turnover from those rigs that we do with floating lines. Using the biggest diameter leader but that is practical (usually around .028”) will temper the kick of those lines, especially if they are cast with a less then sexy, more rounded loop.
Welded loops are another complication. They are made by folding the line over itself and then magically welding the sections together. That makes a short section that is double the mass of the line tip. That extra mass can be very noticeable when good casters (like all Sexyloops members!) fish with light lines, say 4 wt. and lighter. I usually remove the welded loops from those lines and attach my leader butt with a very light 2 turn needle knot. Even the extra mass of a 5 turn nail knot is noticeable on very light lines. Most people don’t notice, or care, but if you are looking for the smoothest cast with light lines give that a try. The extra tip mass due to welded loops isn’t ideal but is unavoidable and most people think the convenience is worth it.
Bruce

[Mangrove Cuckoo]

Thanks Paul!

And be sure to thank Bruce for me too!

The information will give me some things to play with in the field. On some combos I try to match rod/line/leader and fly as best as I can. It takes a bit of fiddling, but when you get things right it is something special.

I'm sure it is very important with the lighter lines and dry fly techniques, but there are some interesting scenarios down here where presentation is much more important than most think. The heavier the tackle the harder it gets.