Copyright 2017 - Woods Designs, Foss Quay, Millbrook, Torpoint, Cornwall, PL10 1EN, UK
  • home built Flica 37

  • plywood Romany 34

  • lightweight 14ft Zeta mainhull

  • Strike 15 trimaran at speed

  • 28ft Skoota in British Columbia

  • 10ft 2 sheet ply Duo dinghy

  • 24ft Strider sailing fast

  • 36ft Mirage open deck catamaran

Several people have asked me about fitting the Aerorig to their catamaran. The Aerorig is a trademark name for a unstayed mast where the jib and mainsail are attached to the same very long boom.  The Aerorig is not patented as its been used for years by model boat enthusiasts. It was also used on the 70' Elf Aquitaine in the 1984 OSTAR. It has also been used on several of my designs, most notably the Savannah 26. In October 2000 I sailed this boat 1500 miles singlehanded up and down the eastern seaboard of the USA from Savannah to Annapolis. So I now have a pretty good understanding of how it works. As with all things there are advantages and disadvantages.

To my mind the advantages are:
Easy sailing: The sails are always working correctly, whatever point of sail. Maybe it would be better to say the rig works to 95% efficiency all the time. A conventional rig may work to 100% if you're an expert, but less if you're not. A conventional rig needs extra downwind sails, ie spinnakers. The Aerorig doesn't. There are only light loads on the mainsheet (but not as light as claimed), and once unrolled there is never a need to adjust the jib sheet. Self tacking, but of course that is only an advantage during the manouever itself.

The disadvantages are:
The rig is very heavy, leading to more pitching and less load carrying. You probably need to modify the cabin. The minimum "immersion" of mast into cabin is about 1 in 7 ie a 35' high mast needs 5' of bury. Also the cabin has to be wide enough to spread the load. Its usually OK with a conventional bridgedeck cabin (although you may need to add a nacelle). Impossible to fit on an open boat and a bit awkward on a boat with a cuddy like the Savannah.

A smaller sail area, especially in light winds and certainly when sailing downwind. That's because the jib is very small (only 20% of the total area) to maintain the correct balance. You can't motorsail safely to windward with both sails unfurled. It is possible to sail an Aerorigged boat backwards. A nice party trick but about as useful as reverse on a motorbike. But I discovered the hard way that the boat could sail backwards in a strong wind when I thought I was motoring forward. After a narrow shave when going under a bridge I always rolled up the jib before motoring. When reefing the jib must be furled first or the rig unbalances

It's a very expensive rig. With the case of the Carbospars/Forespar rigs a lack of attention to detail and unfortunately a lack of customer aftersales service. I could recommend the concept to those cruisers who wouldn't dream of using a spinnaker, but unfortunately I can't recommend products made by either Forespar or Carbospars.

NOTE: This information is now largely academic as Carbospars have ceased trading, hence Aerorigs are no longer available.