Spinnaker, Gennaker or Code Zero – Which sail suits which course?

If your boat is equipped with spinnaker equipment, you will have a perfect downwind angle. With a spinnaker you can easily sail with a wind angle of 180 degrees. So that the wind comes directly from the stern. However, directly in front of the wind, the wind speed and the speed the boat makes through the water cancel each other out. If 10 knots wind speed blows and you have a boat speed of 4 knots, the true wind is only 6 knots strong. If you change course to a wind angle of 160 degrees instead of 180 degrees, the wind vectors change. Wind speed and boat speed do not cancel each other out as much. So the boat sails faster. If the target is directly in front of the wind, it can be faster to cross in front of the wind and to jibe more often. There are different designs for spinnakers.

Of course there are many different sail designs for spinnakers. Flat cuts with which you can sail higher in the wind. Full and bulbous designs for more power before the wind. Spinnaker made of light cloth for low wind, and heavy cloth for more wind. Genrell you can say that the perfect wind angle for a spinnaker is between 180 and 130 degrees wind angle.

Spinnaker pole with windward sheet must always be in 90 degrees on the telltale hanging on your shroud. If you don´t have your telltale on the shroud, then put one. If you don´t put one, then you can use wind arrow on your top mast. If you don´t have even an arrow, then you should have always spinnaker pole in the extensenion of the main boom (same direction lining).  Main point of trimming the spinnaker is „to let him flow“ all the time while windward upper shoulder is slightly clapping, but not overlapping. If wind is gaining it is important to fix spinnaker with both sheets as closest to the front stay. You will be able to keep the boat steady with high waves like that.

The spinnaker has a symmetrical design. The spinnaker halyard at the head of the sail, the afterhaul upwind on the spinnaker pole, and the sheet downwind on the clew.

A gennaker is cut asymmetrically. The neck on the luff is firmly attached to the bow, or better yet, to the bowsprit, the two sheets to the clew, and clearly the halyard to the head. Due to its asymmetrical design, you can sail higher upwind with gennaker than with a spinnaker, although the sail area is almost the same. However, also not as low downwind as with a spinnaker. The gennaker is perfect for long space courses with a wind angle in medium winds between 90 and 140 degrees. If the wind freshens up, you can drop down to a wind angle of 165 degrees with a gennaker.

By the way, with a recovery hose, setting and recovering a gennaker is very easy and safe for any cruising sailor and professional with a small crew.

If you are entering in the position which is slightly lower then maximum up‐wind course, light(er) conditions, too high to gain optimum speed for Gennaker, then is perfect moment for Code Zero. For Code Zero, we can say is even 1 step easier to use then Gennaker. Code Zero comes usually with the whole system with small removable furler attached to Code Zero (as fixed part of the Code Zero).  The attachment is the same as for the Gennaker. The furler is usually with removable system with elastic rope that you can attach on any place on stern that you find hard enough to holdout the force and to be clear from all other systems. It is very easy to hoist and to store. Usually it is made to hold even a bit stronger conditions. It is great sail that can compensate Genoa, but not Gennaker. With Code Zero, you are in position to achieve much more speed in lower angels then with Genoa / Jib. The maximum wind angle for a Code 0 is approximately 120 degrees wind angle.

So the choice of headsail on half-wind courses, space sheets or downwind courses depends on the course. Which sail you then really choose also depends a bit on the experience of the crew, the number of people on board and the area of use. For cruising sailing, the gennaker and code 0 are certainly easier to handle. If you are a sailor who is a bit more confident and have at least three people on board, you will have a lot of fun sailing a spinnaker. Any sailmaker will certainly be happy to advise you.