Code Zero Sails
Article by Simo Brummer - owner of Sun Fast 31 "Simone" based in Finland
Code 0 - sailing faster than the wind with a jeanneau cruiser.
I am a happy owner of a Sun Fast 31 since some years (see the owners list / Simone / Simo Brummer).
This year I have added a new genoa to my limited wardrobe (main, heavy genoa on furler and spinnaker) in order to improve light weather sailing and reaching.
The genoa is a so called flying Code 0 sail, which means that it is a lot larger than a Genoa 1. The Sun Fast Genoa 1 should be about 27 m2. As I have only a normal genoa on a roller I guess the size is around 24 m2. The new Code 0 has an area of 35 m2 so that the total sail area upwind is about 23,7 (main) + 35 = 58,7 m2. This gives some real extra power to the boat.
The sail is designed to work fine up to 40 ° apparent. This means that it is different from a normal Genoa 1 which should be able to go up to 32 or better. There is no limit down of course but at 120° a spinnaker becomes the obvious choice if not earlier. The sail is also much smaller and very different from a gennaker which is designed to be a down wind sail and cannot do better up wind than 65°.
The sail is designed to resist to an apparent wind up to 13 m/s and it will never be thrown at such a gale of course as there is no use to have extra sail area at high winds at all in normal cruising. The material is heavy spinnaker nylon, which is an inexpensive material and helps to keep the cost down. It is of course not a racing sail as the rules do not recognize such a sail, it is thus for fun only. You cannot tack with it without rolling the sail first in which also lets one understand that it is not really a racing sail at all.
I have tried out the sail in variable conditions and my experience is as follows :
The hardest wind has been 15-16 knots apparent at 40-50° which is already out of the design area as at such a wind the boat sails handsomely with its normal genoa. I am not able to say if there was some gain, but all went without any problems.
The results are pretty amazing when the wind is weak. At 8 knots true wind you can well get a steady 5 knots on the GPS, which is already quite a nice speed. At 9.5 knots apparent you can reach 6 knots. I think these are good speeds and the boat handles in a very nice way as there is some pressure on the sails even at low winds.
The sail works from about 40 ° to more than 130° and according to my experience the area were the boats sails really very well is large. It has a big effect on the apparent wind as well. When you are at apparent 80 you might find that the true wind is at 110 or so. The effect of the sail is based on two factors, the area itself and its effect on the apparent wind direction and apparent wind speed (when close hauling).
I do not have enough experience to know where the sail can be put when reaching at 70 / 80 / 90 / 100°... but I am convinced it can go very far.
One of the special features of such a sail is that it does not call for force at all. It is as easy to hoist, up, to open, to roll in, to take in and to lower directly to the forward hatch. The roller is a Harken roller which works almost without friction. If I know that I am going to use the sale I hoist it up already in the harbor before getting out and take down only when back. The successful rolling of the sale takes some training, the halyard should be rather tight and the sail should be free when rolled.
For reasons of safety and comfort cruising boats are designed so that they are clearly underpowered in light winds. This is when many people like to sail but they find their boats slow and no responsive, that is they loose much of the fun.
A code 0 genoa is a way to tackle this problem.
The photos are taken the main down in order to show the sail better.
Additional pictures of the SF 31 with the 35 m2 code 0. As you can see there is no much of a wind at all If I remember right the speed was between 4 and 5 knots.
There is also an answer on the question whether it is possible to achieve the wind speed, the answer is yes.
The boat makes more than the true wind speed at true wind speeds between 3 and 5,3 knots or so. When the true wind is at 95 ° around 4 knots you will get more than 4 knots in boat speed and an apparent wind angle of some 45 ° and apparent wind speed of 5,5 knots. At about 5,3 knots the true wind speed catches the boat speed as the resistance of the boat is increasing faster than the power on the sails. With a larger boat this threshold would of course be pushed upward.
Comment by Daniel Andrieu the designer of SF 31 and many well performing Jeanneau yachts :
Many thanks for your note about Code#0 on your SF31 I full agree with the whole of your comments, and in particular with the angles of apparent wind.
The only comment that I would add is that this sail to be correct must be designed with SHW < 75%SF and that of this fact it is assimilated in IRC and
ORC to a genoa, or an asymetrical spinnaker with a lot a penalty... Thus, it is perfect for cruising.
The second part of the comment concerns the way the handicap rules such as IRC treat a sail of this type. Daniel has it right of course and this sail is not designed for race applications at all.
Some words on the origin of the sail:
I have been watching the Vendee globe and other races of that sort. The achievements of those sailors and boats are quite extraordinary, actually incredible but true. I reasoned that they must have a secret weapon in the rigging, a kind of flying carpet that allows to sail fast with a reasonable effort and comfort and security. It is obvious that they must sail very well even in rather light weather.
Then I looked at some photos on those fast modern boats like the one enclosed in here and noted the huge difference between the apparent wind angle (the one that the sails meet) and the real one that you can see on the water (a Class 40, of course I did not want to go that far, but the principle appears here very clearly).
Then I asked myself is there something for me in it taking into account that I am only cruising, put a high value on ease, comfort and security and sail also many times short handed.
This sail is a combination of all that is mentioned above applied for cruising.
For more information on the sail itself, the link below is to WB-Sails who designed this sail according to my wishes.
The roller cannot be installed without some modifications and a small bowsprit (in glued teak), which serves also as a step when boarding was also added.
Details of the bowsprit