Upwind performance tweaks
Just wading in here rather late as I haven’t been a regular visitor of late. There are a few things to consider if you want to improve the pointing ability of a balanced lug sail. The two most important things to look at are the luff and the leach. MIK has kept the basic setup pretty simple and it works well for all kinds of cruising sailing and it gives surprising performance, but this is largely due to a very generous sail area and a light hull with a relatively low wetted area.
If people really want to up the ante on performance upwind in a fresh breeze as Warmbeer was after, there are a number of tweaks. These have been well documented, but to summarise a few, these are:
· A tight luff
· A tight leach
· An immoveable throat fixing and good control over the throat-peak tension
· Well adjusted helm
· Boat trim (centred crew weight, or even further forward, and sailed as flat as possible)
· Speed to keep the foils working to provide maximum lift
For a tight luff, you really do need considerable tension on that downhaul, so consider a minimum of 6:1. More would be better, because the downhaul is doing the job of the kicker as well. You will need a loose tether to the mast to keep the boom against the mast when the boom is on the lee side of the mast.
It is impossible to get enough tension on the leach from the basic downhaul, as the position next to the mast is simply too far forward along the boom. If you are really chasing upwind performance, then I’m afraid you will need a kicker or vang as we call it is Oz in order to flatten the head and tighten the leach. This will also need to be something fairly hefty, like 6:1 as a minimum, but preferable up to 15:1. It’s a big sail we are tweaking. This does mean a really stiff boom is required, as moving this sort of power along the boom is going to bend it severely, or break it like I did. I won’t go into the pros and cons of loose footed vs lashed, but in my mind, it’s chalk and cheese. Loose footed is the way to go for ultimate control of the foot. Pulling on the outhaul also opens the leach more when you need it.
It’s possible to get the GIS sail set like a blade for excellent upwind performance. You won’t be tacking through 80degrees, but you can definitely achieve less than 90 degrees with the right setup.
There is not much difference in performance or height between either tack. In fact it’s hardly noticeable. If your tell tales are too close to the mast you will get false readings from them due to the turbulence from the mast. For upwind, you will need some telltales ahead of the mast. Another set about 600mm behind the mast and about 400mm up from the boom should be enough. Two leach telltales are also beneficial if you run by the lee. For maximum performance of height vs speed, you need to keep the windward telltale flicking about half the time. The leeward telltale should not be stalled unless you are driving hard over or into a big wave.
I found pointing ability also improved by moving the traveller back to the transom. The sheeting angle is therefore tighter and closer to the centreline than the “normal” position. The traveller line needs to be low stretch dyneema or spectra line (abt 4mm), bar tight and left that way. If it is loose, the boom will be too close to the centreline and speed will suffer.
If you have a vang/kicker, and sailing in 15kts or above, it needs to be tight enough that the boom does not rise when you sheet out in a gust. If the boom rises when you sheet out, the sail gets fuller and powers up. Not what you want.
If you reef at all, which I don’t, upwind performance goes down the toilet and none of this is really relevant. However, by getting control of your sail with these tweaks, you can depower more efficiently and sail in a stronger wind before having to reef.
Do these basic things and you’re flying upwind :U