Rio Fathom Sinking Fly Line
RIO Fathom is a family of full-sinking fly lines developed specifically for stillwater fishing. The S6 profile takes the fly below the surface and keeps the presentation in water that calls for a sinking set-up, without using a separate sink tip. The supplied family range includes WF5S6, WF7S6 and WF8S6, corresponding to line weights 5, 7 and 8. No specific sink rate has been provided, so S6 should be treated as the manufacturer’s variant designation rather than a basis for quoting a rate in units of time or distance.
Profile and fishing use
Short, quick-loading head design reduces the number of false casts needed before delivery. Its weight is arranged to load the rod promptly and help the angler send the fly out efficiently. This is useful during repetitive stillwater fishing, where every completed retrieve is followed by another cast and keeping a sinking line in the air for unnecessary false casts adds effort without extending the presentation.
- Full-sinking stillwater fly line with an S6 profile.
- Family variants: WF5S6, WF7S6 and WF8S6.
- Colour contrast identifies the transition between the head and running line.
- The Hang Marker indicates when to stop retrieving and begin fishing the hang.
A clear colour contrast between the head and running line provides a practical visual reference. It makes it easier to see when the head is outside the rod rings and the line has reached its intended loading point for the next cast. This supports a repeatable casting sequence, helps the angler manage how much running line is released and reduces the need for additional false casts.
The built-in Hang Marker assists with control during the final stage of the retrieve. It shows when to stop stripping and leave the fly on the ‘hang’ before lifting the line from the water. This encourages the angler to fish the last part of the presentation deliberately rather than moving straight into the next cast. The marker is a positional reference on the line, not a mechanical stop.
The S6 versions use Density Compensation technology. Its purpose is to support control of the sinking profile and the fly as the line descends and is retrieved. Combined with the short head, contrasting running line and Hang Marker, it creates a practical system for the stillwater angler who wants to cast repeatedly, recognise the loading point and manage the conclusion of each retrieve with greater precision.