This section weighs 0.92kg/m, is 100mm long and 41mm wide. As a comparison, the Selden Cumulus section (as used on Fireballs, RS400s, RS200s etc) weighs 0.95kg/m and is 69mm long and 58mm wide.
Many in Oz fit a composite upper mast above the hounds which is more flexible, but interestingly the 2007 NSW State Champion used an all ali mast (as do I), so the jury must still be out on the benefits. I suppose the most important thing is to get your sails cut to match whatever mast you use. All carbon masts have only been legalised this year and to my knowledge there is only one brave soul who has so far taken the plunge and owns a C-Tech made mast. It looks great, as can be seen in the photos below, and has an integral luff track.
There is a great guide to tuning wing masts here. Don't be put off by the apparent complexity - even in 'set and forget' mode, wing masts offer significant advantages over traditional fixed masts!
Sail Aspect Ratio - Why Does It Matter?
Coming soon...
Square Head Sails - What's the Benefit?
Better gust response and better aerodynamics. The interview below is from the North Sails website, talking about America's Cup sail development:
Square-top mainsails seem to have reached an extreme. What’s the advantage of a square-top?
Calder: A square-top configuration lowers induced drag by virtue of the increased width across the head of the sail. Historically, the rigs of Cup boats haven’t been good enough to support a large girth at the top of the sail, so the Cup syndicates have made a big commitment to integrate the mast and the sail. From a design point of view the goal is to be able to support the head area we want, which means increasing the rig stiffness so that it won’t be overwhelmed by the added loads of a square-top. What we’ve seen is that as the rigs have gotten better the sails have gotten bigger.
With a square-top, how big is too big?
Calder: A few teams went overboard with the square-top before backing off to a threshold that proved palatable. You have to be able to control the head of the sail within the wind range the sail is designed for. Ultimately, the achievable Twist profile to some degree governs the width of the current square-tops. That said, if we could build a rectangular sail, we would—aerodynamically, that would be ideal. But thus far we haven’t been able to overcome the structural challenges in either sail or rig.
Do you see the Cup-style square-tops moving into other boats and classes?
Calder: Certainly the notion of a wide-headed sail has been around for quite a while. It probably started with the large French multihulls, which also introduced chimney-shaped wing masts. I sailed on the Open 60 Primagaz in 1993, and our mainsail had a 1.6 meter (5-foot, 3-inch) square-top—we thought we’d gone completely over the edge. No one back then dreamed of having the head of a mainsail that wide, and we ended up breaking the mast as a result of the loads. We’ve been evolving the square-top geometry, and rigs, ever since.
Now we’re seeing more and more square-top mainsails in other multihull classes, such as the F-27 and beach cats. In monohulls the square-top concept tends to be constrained by class rules and handicap rules. Under IRC the rulemakers have increased the upper 1/8 girth of the mainsail, but they haven’t allowed the actual head width of the sail itself to get appreciably bigger. Even so, some of the maxis, such as Morning Glory, have sported square-top mains, ignoring the rules and going for all-out performance.
NS14 Hulls - How Are they Special?
The NS14 hull is one of the lightest boats of its size around. But so what? Why does that matter?
There are, in fact, several reasons why a light hull is good. For starters, it is easier to move the boat around the boat park and to pull up the slipway at the end of a days sailing. At just 64kg it is even light enough to put on the roof of your car, saving the expense and hassle of needing a road trailer to transport your boat (I bought my boat back from German/Swiss border on the roof of a Mondeo). But the real benefits of a light boat can be felt on the water. Lighter boats are faster - and below are some of the reasons why.
1. Archimedes discovered many, many, many years ago that a boat displaces an amount of water equal in weight to the weight of the boat. Heavier boats therefore displace more water than lighter ones. Now, for every boat length forward that a boat sails, it has to push aside this amount of water. Pushing water aside takes energy, and pushing more water aside takes more energy. Heavy boats need bigger sails to go the same speed, bigger sails make the boat heel more, which require heavier crew to keep it upright, which increases the water displaced, which needs more sail area, which needs bigger crews...
2. Heavy, more voluminous, boats also have a greater wetted surface area (WSA). WSA is absolutely critical to light wind speeds and is a key parameter that designers measure when designing new boats. NS14s have extremely low WSA, due to their light weight and cleverly shaped hulls.
3. Lightweight hulls can also start planing at lower speeds, as less force is required to lift the boat.
4. Additionally, the so called 'hull speed' of the boat (effectively the maximum speed a boat can do whilst displacement sailing, i.e. not planing) is higher for boats with a low displacement:length ratio (DLR).
5.The combination of low planing speeds and high displacement speeds serve to greatly reduce the large 'hump' in resistance that many boats suffer from in marginal planing conditions. This hump occurs when a boat reaches it's hull speed. At this speed, the bow wave created by the boat has a wave length equal to the length of the hull. This means there is wave wave crest athe the bow and one at the stern. Attempting to go any quicker puts the bow wave at the stern even further aft, so the the transom is sitting in the wave trough. The boat is then at a very unfavourable trim and is trying, in effect, to sail up its own bow wave - a bit like cycling uphill.
Boats that are too heavy will not start planing until speeds in excess of hull speed are reached and therefore struggle to develop enough power to start accelerating on to the plane. They will mange eventually, if there is enough wind, but there is a sticky point where more wind doesn't equal more speed. You will see this referred to in sailing literature as 'semi-displacement' or 'forced mode' sailing.
Typically, many dinghies reach hull speed in about 8 knots of breeze, but don't plane until there is, say, 12 knots. So, in winds between 8 and 12 knots these boats go hardly any faster. There is more spray and noise, but no more speed.
This is frustrating not only because these are very pleasant (and common) wind speeds, but because light sailors are disproportionately advantaged in these conditions. Lighter crews require less speed to get planing, and will therefore be able to plane in conditions where others are still stuck in the forced mode. It follows that with equal skill levels, a lightweight team will always beat a standard weight team in the Force 3 winds.
The NS14 evens things up by extending the maximum hull speed beyond the speed at which planing commences. Therefore, whilst a lighter team may plane earlier, they will not be going any faster than a heavier team accelerating in displacement mode. This results in much more even, fairer, racing.
It should be noted that whilst a low DLR is pre-requisite,on its own it is not enough to create a humpless transition - there are many light boats that still suffer from an extended forced mode. A carefully shaped hull form is also needed, and the NS14 probably leads the world in this regard. The precise subtleties are a mystery to me (and most others!), but around 1996 hull forms began to emerge in the NS14 class that were significantly faster than before. They may not look radical, but believe me, the acceleration from a NS14 is extra-ordinary and in a different league to heavier, mas produced classes.
I want to buy one!