This drives bigger thimble widths which often forces you to buy a larger furling unit than is required on pure SWL requirements. However, cable sizes are always bigger in diameter relative to bottom-up cables.Loads are much smaller for top-down furling and therefore you should be able to go down a size.Despite the obvious choice of whether to go for a dedicated top-down furling unit, Top-down furling has other consequences on unit size.It is by no means guaranteed that this distance is enough to accommodate your thimble/cable. the distance from the pin to the back of the jaw.
Various jaw widths and pin sizes are available across the different unit manufacturers but this will definitely limit your choice to a number of suitable units.If so, the thimble width on your furling cable is critical to the specification of the unit.
#Code zero furler code#
However, a general rule of thumb is to use the same size as the code zero which reduces the number of furlers you need and/or build in some redundancy.ĭo you have an existing sail / furling cable?
Due to the significantly smaller sail areas relative to code zeros and gennakers, on the same boat, Staysail furlers can often be a size down. If you have a multihull this will almost always push you into the next category up due to the increased stability and therefore, loads. If you have a particularly heavy displacement boat and/or particularly large and powerful sail then you might consider a slightly larger unit. Summarising the data across a number of manufacturers, here at Upffront, we use the table below as an initial guide to required SWL, based on your boat size.Īs an example, if you have a 46ft boat you should be looking for a furling unit with a SWL of 3000-4000 kg, whilst a 50-53 ft boat might require something in the 4000-5000 kg range. It is possible to generalise, based on boat size, to get a ballpark SWL and then consider a number of variables to guide your final decision. At this load, Harken suggest a maximum recommended boat size of 33ft, whilst Karver push the boundary out to 36ft, and Facnor go all the way up to 39ft. and manufacturers cannot agree on the boundaries either! For example, Facnor, Karver and Harken all have code zero furlers with a SWL of 1500kg. Unfortunately few, if any, people really know the SWL of their forestay or their Code zero tack load. The correct method for specifying a unit is by the Safe Working Load (SWL) and this is the one consistently available piece of information, across all manufacturers. How do I choose the right code zero or gennaker furling unit for my boat? Data from 8 well-known manufacturers is reviewed and conclusions drawn to help guide you to an appropriate unit for your needs.Ī quick review of the available data will tell you that sizing the correct furling unit for your boat is NOT an exact science!
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