Fathom

The shape of the Fathom is somewhat representative of the Rumour, but altogether larger. It was built for wide, stubby twin fins that are more similar to a fish. It is not a keel but is used in the same surfboards that would normally use a keel fin. More pivot than a keel, giving a feeling of greater movement with a tighter turning radius. It is worth mentioning that this fin was also intended for bigger humans using high-performing twin fin surfboards, which is why the Rumour and Fathom share many characteristics.

The Fathom has been most used in surfboards that prefer slightly more horizontal as opposed to vertical surfing. Typically thrown in fishes with a wide tail block or something similar. 

The biggest question is when to use this fin as opposed to the Encompass. The Encompass is meant for classic keel fishes and the style of surfing that they include. More drawn-out, slower transitions, but a great amount of speed due to the wider, straighter outline of the surfboard/fin combination.

The Fathom adds a slight high-performance component to a wide-tailed twin fin. It has a faster pivot and allows for more vertical surfing compared to the Encompass. Where the Encompass is meant for a straighter outlined surfboard, the Fathom is meant for a curvier fishy outline.