What is a Top-Down Adapter?

We are constantly reporting on the latest innovations in the marine industry which offer weight savings whilst, at the same time, increasing safety factors. The result: lighter, faster, safer and more exciting sailing.


Image credits: Facnor 


The top-down adapter, also known as a tack swivel, is an increasingly popular evolution of the top-down furling system. This technique provides cruisers and racers alike, simplicity, safety and speed for the handling of loose luff sails such as asymmetric spinnakers and gennakers.

Cruisers can store, deploy and retrieve these sails, as they would a furling head sail, from the safety and convenience of the cockpit. Whilst racers are increasingly using top-down as a super fast and efficient retrieval system for both code zero’s and asymmetrics. For more information on top-down vs bottom-up furling check out our blog here.


Evolution of the tack swivel?

When top-down furling was first introduced, around 2005, manufacturers started producing what are now called “dedicated” top-down furling drums. To allow the tack of the sail to fly freely, whilst the cable transmits torque to the head of the sail (where the furl begins), requires a “free-floating” bearing to be added onto the traditional bottom-up furling drum.

See images below

Capture (1)                                    Untitled 
Karver KF2 – Traditional Bottom-up drum                  Karver KSF2 – Top-down drum with integrated tack swivel
One of the more important elements to the setup of a loose luffed sail is the length of the strop connecting the tack of the sail to this “tack swivel”. Once setup, there is no need to alter this length which leads to the furling drum being stored with the sail in the bag when not in use. This means that multiple asymmetric sails leads to multiple drums, which adds both weight and significant extra cost.

The top-down adapter has been developed by manufacturers in response to these issues and it “does exactly what it says on the tin” – it adapts a standard bottom-up furler for top-down furling. With the tack swivel, now mounted as a separate, detachable fitting, the asymmetric sail can be removed from the drum, allowing the same drum to be used for multiple sails.


For cruising sailors, this has almost become a “no-brainer”. The top-down adapter offers sailors a simple, easy to use and cost-effective furling system for both a code zero and an asymmetric gennaker; an increasingly popular reaching/downwind cruising sail combination.


More interesting however, is the current take-up of the top-down adapter in grand-prix racing circles. Whilst a top-down adapter on a standard drum is heavier than a dedicated top-down drum, there is a net weight gain when you consider multiple asymmetric sails using a single drum. Manufacturers have also always tried to reduce the profile of furling drums to maximize luff length, but this becomes a moot point with a loose luffed sail on an adjustable tack strop.


Click this link to watch the KZ Race Furler on a Rambler 88! 

At Upffront we stock top-down adapters / tack swivels from a number of manufacturers:


karver                      Capture2                                Capture3 (1)

          Karver                                                                 Ronstan                                                                  Facnor

Karver’s have long supported the optimum weight and windage of dedicated top-down drums. However, in the last few years they have recognised the changes in the market and now offer both dedicated drums and a full range of top-down adapters.


Ronstan have taken a mixed approach – on their smaller units they offer a choice of dedicated bottom-up and top-down drums but on their larger, more expensive 5t and 8t SWL units, they now offer top-down adapters on standard drums as the only option.

Interestingly, Facnor have never offered a dedicated top-down drum, favouring the top-down adapter (which they refer to as their Fast Thimble) across their full range.


To learn more about bottom-up or top-down furling click the link below to download our free guide. If you still have any questions you can always contact us on support@upffront.com

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