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Product Comparison: Top-down furling systems for a 42ft cruising boat

by Diego Sosa, Upffront 31 Oct 2018 09:00 GMT
upffront.com looks at top-down furling systems © Eric Beauge

Say you have a 42ft cruising boat and are looking for options for a top-down furling system (for free-flying downwind asymmetric sails). We take a quick look at your main furling unit and cable choices in this size range.

Furling unit

This is firmly in the 2500kg Safe Working Load (SWL) arena and you have a good number of choices. The main decision that needs to be made is whether you want a dedicated top-down unit or go the more flexible route and use a bottom-up furling unit together with a top-down adapter... We will explain below.

A dedicated top-down unit has a swivel mounted above the drum, where the tack of the sail is attached, to allow it to remain still while the drum and cable rotate (that's how the furl starts at the top and works down). A dedicated unit is the lightest option but, if you have more than one downwind asymmetric, you will normally need a drum for each sail which can add to the cost.

The Karver KSF2 and the Ronstan Series 160 have SWLs of 2500kg and 3000kg respectively and would be the appropriate unit for this boat size. The Karver unit is marginally lighter (50g) and has a slightly smaller drum (151mm vs 160mm for the Ronstan) which is better for top-down furling (assuming you have good sized winches to enable you to generate the required line speed... and "speed is your friend" when it comes to top-down furling).

The alternative to a dedicated top-down unit is to go for a bottom-up drum and use a top-down adapter which is permanently connected to the sail/cable. The top-down adapter is connected to the torsional cable with the line, to the tack of the sail, preset and it is all stored in the sail bag. When it comes time to hoist, the eye of the top-down adapter is slotted into the jaw of the drum, the swivel is attached to the halyard and you can hoist out of the bag.

The top-down adapter adds some weight but if you are cruising, the advantages of being able to use the same furler for both bottom-up and top-down normally outweighs the 300-400g weight penalty. Both Karver and Facnor offer a top-down adapter option.

In conclusion, if you only have a single downwind asymmetric and want the weight advantages of a dedicated top-down furling drum then we believe the Karver KSF2 offers the best performance and value. However, if you are setting up for flexible cruising and using the same unit for multiple sails, the Facnor FX+2500 gives you the best weight and value for money.

Torsional Cable

Reviewing your torsional furling cable options could not be simpler at upffront.com. Go to the Furling Cables / Top-down subcategory page and select your approx required cable length from the technical filter drop-down. For example, if your cable length is 16m we recommend you select 15750 + 16000 + 16250 in the filter to give you a good view of the available cables.

Your cable luff length is likely to be in the region of 15-17m, depending on your rig setup, and for top-down cables we have three primary choices available:

  • Armare K49
    • The Armare cables are very high quality, durable and reliable
    • The K49 core is relatively heavy compared to other options but they deliver excellent performance and are very reasonably priced
  • Gottifredi Maffioli Aircore
    • This is Gottifredi Maffioli's specialist top-down cable with a core of hollow filament fibres surrounded by Dyneema® SK99. Building diameter without increasing weight is the key to a top-down cable and the hollow Aircore does this job extremely well
    • The result is a very lightweight cable with very high torsional peformance
  • Hampidjan
    • This Hampidjan custom furling cable is a cross between a torsional rope and a custom finished cable
    • It is based on Hampidjans excellent range of torsional ropes but has been overbraided in the factory to your specific length requirement
    • This is an excellent budget option which is strong and reliable but the only downside is the bulk of the area before terminations where the rope core has been doubled over, around the thimble and overbraided

For a general/offshore cruising application, upffront.com would recommend the Armare K49 cables.

Furling line

Last but not least you should not forget your drum furling line! We have an extensive range of furling loop lines. The first consideration is line diameter, which is specific to the furling drum. At this size, the Karver and Facnor units are 8mm while the Ronstan is 10mm. Next you need to consider from where you will be controlling the furl, but for most people at this size, it will be the primary winches. We normally recommend the distance from the furling unit to the primary winch plus 2m, which, for a 42ft boat will be approx 12m loop length.

As with most things in life - you get what you pay for and your choice between the cruise or performance options will depend on your type of sailing. The Gottifredi Maffioli Loopline 78, in the performance option, has been specifically designed for use as a furling line and has a very tight, durable cover over a performance core. As a general guide, upffront.com would recommend that the performance version should be used whenever you intend to furl using a winch and the cruise furling line reserved for hand furling.

Would you like a tailored proposal for your boat and style of sailing?

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