Jonas Magnusson

Now it’s time to buy a new floating fly line. I looked at Scientific Anglers’ floating lines for fresh water, and I found they offer seven different fly lines. It is easy to pick the wrong one. Which one is right for you?

When we need a new fly line the first question is –  what is the size/weight of the fly we intend to use? When we have that one down, we can choose our line weight. The line’s mass profile is critical for instance when we plan to throw big and heavy. The mass profile of the line is simply how the head’s mass is distributed along the length of the head. The mass profile has a great impact on how the fly turns over at delivery. Points to consider – Delicately tapered lines can’t cast heavy flies, but aggressively tapered lines can cast both light – and heavy flies. How the line works is caster dependent. For any particular caster lines with long tapers and small tips will be less powerful that lines with short tapers and big tips, all else being equal. Beginning casters can’t make long tapers with small tips work. The great casters can make anything work.

So, now we understand why SA offers all these different lines – these lines all have different mass profiles and various head lengths and are all designed for various scenarios. The first six are designed for cold water and the Bass Bug line is designed for medium to hot water.

What to look for?

Line weight – note if the line is overweighted. Some lines are 2 sizes heavy. Head length – lines with long heads can be cast far by good casters. Long-head lines don’t help middling casters at all. Short-head lines are often heavier and thus load the rod more quickly. However, long-head lines mend more easily.

(Saltwater lines generally have shorter heavier heads because you need to be able to cast quickly.)

The head‘s mass profile – Is the mass in the head evenly spread over its length or is the mass pushed forward?

Rear taper – long rear taper is the hallmark of lines designed to be cast far.

Front taper – long front taper is found on lines designed to be delicate. The diameter of the terminal tip of the fly line matters too. Thin tips will be more delicate than thick ones (everything else equal), but that info is usually not given. Short front taper has a more aggressive turnover.

Aggressive front tapers will land harder than delicate front tapers.

SA´s very best lines are called Amplitude and they are offered both in textured versions and smooth versions depending on our preference. Textured lines shoot and haul better (less contact of line to guides), they last longer and tangle less. I prefer textured lines. Some anglers like textured lines and some can’t stand the rasping sound they make in the rod guides, your choice.


Amplitude Trout. This line is true to weight. The head is quite long at 68’ and the front taper is around 12’. Because of the long rear taper, the line can be cast long distances by good casters and is easily mended. The mass profile – mass pushed forward so it will turn over well. The long front taper makes for a soft presentation.

Amplitude Trout
Amplitude Trout

This line is great for dries and smaller nymphs. This line is designed for freshwater trout evident in the name. (not Speckled Trout a saltwater species).


Amplitude Trout Standard. This line is true to weight. The head is 51’ and the front taper is around 8’. This line is touted as the caster’s line and mending it is easy. The mass profile is pushed forward. This line will probably turn over heavier flies than Amplitude Trout if the terminal tips are equal.

Amplitude Trout Standard
Amplitude Trout Standard

This Trout Standard fly line is designed for dries and smaller nymphs and probably will cast light streamers well.



Amplitude Double Taper. This line is true to weight. The front taper is around 8’. Will probably cast and deliver like the Amplitude Trout Standard. Mending – At fishing distances, it will mend as the previous Trout lines. One advantage of double taper lines is that when the front gets chewed up you simply turn the line around.

Amplitude Double Taper
Amplitude Double Taper


The Double Tapered fly line is designed for dries and nymphs and probably will cast light streamers well.



Amplitude MPX. This one is half a size heavy. The head is 36’ and the front taper is around 8’. The mass is not evenly distributed but is pushed forward and this profile will turn over bigger flies than the first three, because the line is heavier, and the mass is pushed more forward.

Amplitude MPX
Amplitude MPX

The MPX fly line is designed for dries, nymphs, streamers, and indicator rigs. The line works well because of its weight and mass profile.



Amplitude Infinity. Half a size heavy fly line. The head is 49’ and the front taper is around 8’. The mass is pushed forward making for a good turnover. This line can be cast far, and mending is not a problem.  This is a general-purpose line aptly named.

Basically, it is the MPX with a longer head, good for better casters who want to throw long, with bigger flies.

Amplitude Trout Standard
Amplitude Infinity

The Infinity fly line is designed for dries, nymphs, streamers, poppers/big dries, and indicator rigs. It works well because of its weight and mass profile.

If I was to buy only one line for freshwater I would choose the Infinity.



Amplitude Textured Anadro. One and a half sizes heavy. The head is 60’ and the front taper is 3-4’. The long rear taper makes this line the good caster’s dream. The mass is pushed forward, and the front taper is short, and this line will aggressively turn over heavy stuff. The long head is great for line control at longer distances, as needed for steelhead/salmon/sea trout fishing (Anadro – anadromous – sea-going salmonoids).

Amplitude Anadro Indicator
Amplitude Anadro Indicator

The Anadro fly line is designed for nymphs, streamers, poppers/big dries, and indicator rigs. It works well because of its weight and mass profile.


Amplitude Bass Bug. This line is two sizes heavy. The head is 43’ and the front taper is around 4’. The mass is aggressively pushed forward. This line will load a rod quickly because it is HEAVY and turns over the biggest flies.

Amplitude Bass Bug
Amplitude Bass Bug

The Bass Bug line is designed for streamers and poppers/big dries.


The head length data is based on #5 weight lines except for the Bass Bug line #6.

Technical consultant: Bruce Richards