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. A quick review of the available data will tell you that sizing the correct furling unit for your boat is NOT an exact science!
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. Unfortunately few, if any, people really know the SWL of their forestay or their Code zero tack load.... and manufacturers cannot agree on the boundaries either! For example, Facnor, Karver and Harken all have code zero furlers with a SWL of 1500kg. 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.
However, do not despair. 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.
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.
Boat Size (ft) | SWL (kg) |
18 |
500 |
25 | 750 |
28 | 1000 |
35 | 1500 |
38 | 2000 |
41 | 2500 |
45 | 3000 |
49 | 4000 |
56 | 5000 |
60 | 6000 |
70 | 8000 |
80 | 10000 |
90 | 12000 |
As 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.
Last but not least, having considered all the factors above and you still have some options, weight is always a key decision criteria. This is no less important for cruising boats. Saving weight should be on your mind in every hardware and rigging choice made on your boat. Lowering the overall weight of your boat makes it stiffer and more powerful / responsive but also reduces the overall loads. This in turn, increases safety factors, reduces ware and ultimately increase the life of your hardware and rigging.
As a conclusion, these following steps (roughly in order of importance) will help you understand how to choose - Code Zero or Gennaker Furler for your boat:
If you have any questions about code zero and asymmetric furlers, please feel free to email us at support@upffront.com, or click the link below to see our full range: