10/06/2013
Unlike the Scandinavian Cruiser 20 (SC20), “conventional” boats cannot sail dead downwind with an asymmetrical spinnaker, because there is no spinnaker pole to bring the spinnaker clear to windward of the stalled airflow behind the mainsail.
This explains why you see those boats on a broad reach, sailing a longer-than-necessary distance going downwind. It is hard to make up for the extra distance, unless you have enough wind to surf or plane going downwind.
In light to medium air, it is usually faster to sail the shortest distance dead downwind. The SC 20 has a rotating un-stayed mast, so you can position the mailsail with a much more efficient angle of attack, which increases the lift, as there is no stalled airflow behind the mainsail as on conventional boats going dead downwind.
The SC20 main sheet is long enough to allow the boom to swing forward to about 135 degrees, instead of the conventional 90 degrees. This allows you to sail dead downwind with the asymmetrical spinnaker. In addition you should drop the spinnaker halyard about 2’ to help the spinnaker to fly further away from the mainsail (remember to hoist again before you attempt to furl the spinnaker ☺).
In this 135 degree mainsail position, you need to watch the mainsail carefully to make sure it is not luffing at the luff (indicating that you are pointing higher than dead downwind). It takes a little practice to get used to this new way of sailing dead downwind.
In a jibe you will need to grab the mainsheet and pull the boom in to help it to swing across, as otherwise it is very hard to turn into the jibe.
Be careful if the wind is too strong, as the boat will heel to windward, and/or start to rock & roll.
Happy downwind sailing!