I was delighted to read in his "Travels with Paddles" blog that the highly respected coach, Axel Schoevers from the Netherlands, has discovered Flat Earth Kayak Sails! In his enthusiastic write up of the sail he writes "The sail was reviewed in issue 22 of Ocean Paddler Magazine and that article didn't mention or even hint towards the, for me, most rewarding part of the sailing: tracking by edging!"
The first people I saw sailing sea kayaks here in Scotland were all experienced sailors or windsurfers but recently non sailors are discovering the delights of sailing a sea kayak. So I thought I would give a few pointers here to help those who are new to sailing, which might also explain why I did not mention controlling the track of a sailing kayak by edging in the OP article....
As Flat Earth sails become more common, photos and videos are beginning to appear on the Internet, usually with the kayak being sailed with a lot of edge and the paddler in a trailing low brace position. Additionally, some videos show the application of frequent stern rudders to keep the kayak tracking straight. In contrast, Gnarly Dog's video shows his kayak sailing upright and the paddler still paddling!
Every time you edge (or lean) you will loose speed as you have stalled the normal airflow. If you maintain edge for any length of time, in your effort to hold a course, you are creating extra drag and cutting your speed. Since the main point of kayak sailing is to go faster, it helps if sail, skeg and hull configuration are as efficient as possible and are working with each other and not against each other.
So in sailing, you want to keep the rig as upright and steady as possible to keep the wind flowing aft across the sail. In a sailing kayak you steer a course by a combination of sail sheeting angle and skeg. You start with the right sheeting angle, which generally means that you let the sail out as far as possible, without allowing the wind to get round the leeward side of the luff. If you are not a sailor you can thread a piece of fine wool through the luff half way up the mast and about 15 cm back from the leading edge. When the sail is let too far out, the airflow will be going up, when just sheeted in enough, the airflow will start moving back and the telltale will be horizontal.
If you want to sail with the wind about 90 degrees to direction of travel (beam reaching), you trim the sail as above then adjust the skeg to maintain tracking in the right direction. Move the skeg up, if the bow of the kayak wants to go down wind, or move the skeg down if the bow of the kayak wants to go up wind. On both my Quest LV and Nordkapp LV, the balance is so sensitive that I move the skeg slider only a few mm at a time.
With practice you can even sail the Flat Earth rig upwind (at about 45 degrees off from the direction of the wind). You can only do this if you keep the kayak upright. If you edge the kayak, when close hauled to the wind, you will stall the sail and lose speed and then you will need to paddle further off the wind to get going again.
Watching some people new to kayak sailing in Scotland I can always spot the non sailors. The better kayakers try to maintain tracking by edging, those that do not have effective edge control end up using stern rudders.Every stern rudder slows you down, so its much better to get the sail/skeg trim right in the first place. It's all about balance and the kayaker now needs to think as a kayak sailor!
In this photo I have lifted my port edge and this would normally cause the bow to swing round to the left. However, when sailing at this speed in the Nordkapp LV and Quest LV, lifting the left edge causes the bow to go round to the right (this might not happen with all kayaks). I am sailing diagonally down the waves and in this case I feel I am just slipping off the back of the wave, so I am bearing off to pick up speed on a broader reach and hopefully stay on the wave. (At the same time I would normally paddle a little harder as well, but I was taking the photo!)
Broad reaching in waves is the fastest point of sea kayak sailing. So far, my maximum speed has been 24.7km/hr in a P&H Aleut Delphin, see video below.
One problem when sailing in stronger winds is capsizing when launching the sail. The safest way to do this is to reduce the apparent wind acting on the kayak by paddling downwind as fast as you can. Launching with the sail on a dead run (with the wind directly behind you) can also be tricky as the full area of the sail is exposed and fills as soon as it is launched. The best solution is to paddle on a broad reach (wind blowing about 45 degrees from the stern). I mark my sheet so that I can see where to cleat it so that on a broad reach only the rear half of the sail fills with wind. The luff (front) is back winding with wind getting round the lee side of the mast (side away from the wind). This sail sheeting position allows the sail to spill wind.
Once I am travelling fast preferably surfing on a wave, I quickly pull the uphaul and cleat it to launch the sail. I put in another couple of paddle strokes to get the speed up again then I sheet in the sail until the luff stops collapsing. Once the sail has settled I then adjust my direction, retrim the sail and adjust the skeg. You can see all of this in the above video.