Some of you have asked about our staysail setup.
We did lots of work with the staysail on the J/109, and it was very efficient in most conditions. We tacked it to a padeye just aft of the anchor box locker.
With the same setup on the J/111 we got almost no effect. Here’s a shot from Tjörn Runt 2014… trim (and crew position) looks bad, but the difference in geometry is apparent.
Distance from the gennaker tack to the main on the J/109 is 4.05+1.67=5.72 and on the J/111 4.22+2.43=6.65, 16% longer.
We tried several different tacking points, ending up quite far aft. As seen on the first photo, it’s about 100 cm aft of the previous padeye and 50 cm in front of the hatch.
The main effect of the staysail is to increase the flow on the back of the main, and the bigger STL on the J/111 makes the geometry quite different compared to most boats.
You can see the same thing on many bigger modern boats, where the staysail ends up closer to the mast.
Now we’re getting 2-3% speed increase in most conditions, so well worth the effort.
Now we run the staysail from TWS ~6 knots up to 18 knots when we’re planing, and keep the jib up instead.
We need to get some better phots of the sail plan in 2020 :-)
If you want to go full nerd:
THE EFFECTS OF STAYSAILS ON YACHT PERFOMANCE
D.J. Le Pelley, L. Kjellberg, R.G.J. Flay
Abstract. A staysail can be defined as any supplementary sail flown between the mast and primary genoa or spinnaker to enhance aerodynamic performance. Much of the time, huge expense and effort is put into improving the performance of the flying sails with little thought to staysail design and position. Wind tunnel experiments were carried out in the University of Auckland’s Twisted Flow Wind Tunnel on a range of staysails operating under typical flying sails. Flow visualisation of interesting concepts was carried out. The analogy of the staysail as a turning vane that improves the flow over the other sails was investigated. Independent supports were used to determine the load contribution of the staysail to the overall loading of the sail combination. A range of clew heights of the staysail were investigated. A significant gain in driving force of around 10% on average and up to 17% has been demonstrated by correct selection and placement of staysails. Staysail area is not a key factor, with the smallest staysail testing giving one of the largest improvements. Masthead staysails and sailing triple-headed were both found to have a significant performance benefit over a conventional medium sized staysail.