Expert Advice

Furling Mainsails

webcraft Expert Advice
Furling Mainsails

If you want to make mainsail handling as easy as possible, furling is the answer. And that applies whether you have an in-mast system or one that’s fitted behind the mast. A fully-
battened conventional sail with lazyjacks and a Packway will be ideal for many people, but furling provides the ultimate in convenience and control from the cockpit.

Should you decide furling is for you, that is something we will be happy to discuss with you, to ensure you are making the best choice. The most suitable type of sail will be determined by your rig, your budget and your style of sailing. So let’s consider the factors that will influence your choice.

 

WHAT TYPE OF MAST DO YOU HAVE?

If you have an in mast rig by Selden (or Formula, found only on bigger boats), all the opinion are open: You can have a sail with full-length battens, short battens or no battens. On the other hand, masts from most of the French and European manufacturers including Spacraft, Isomat and Z-Spars will give you a more limited choice. The reason is that Selden use a mandrel (the furling spar inside the mast) that is tensioned independently of the halyard and has its own top swivel). This keeps the mandrel tighter, leading to a neater furl and making better use of the space inside the mast.

Other manufacturers’ mandrels are tensioned by the halyard, whose swivel acts as the top bearing. Consequently the mandrel moves around more within the in-mast cavity, leaving less
space for the sail. In addition, Z-Spars have a narrower slot in the back of the mast. What this all means is that unless you have a Selden (or Formula) mast, there will be no room for battens. This will also apply if you have an Easyreef, Tabb, Bamar, the old Reefin’ by Kemp/Selden or our favourite, Facnor.

 

WHAT TYPE OF BATTENS DO YOU WANT?

In recent years, furling mainsails with full-length vertical battens have become increasingly popular. Full battens allow the sail to be built with a roach, whereas sails with no battens have
to have a hollow (concave) leech. The difference can be appreciable, a full-batten sail can be up to 6% larger than a hollow leech alternative whilst minimising any loss in performance
compared with a conventional mainsail. There are buts, however. One is that you can only have full length battens with certain types of mast, as discussed above. This means short battens are a compromise between full-length battens and no battens in terms of performance and price, but you need to check their mast compatibility with us before purchase.

WHAT CLOTHS DO WE USE?

Sails with full-length battens cost more because of the battens, they also cost more because they need to be built from a cloth that is stable, most critically in the leech, to keep the battens
in alignment and rolling in and our the furler smoothly. A stable leech is also needed for both the short battened and battenless furling mainsails.

We believe that the best cloth for furling is Vectron. Due to the mix of polyester and Vectran (a multi-filament yarn spun from liquid crystal polymer), it is a strong, light and durable choice. The alternative to Vectron is a finely woven, high tenacity polyester that uses a minimal amount of stabilising resin. The upgrade to a polyester that uses minimal resin will reduce the breakdown in the stability of your cloth and therefore increase the lifespan of your furling mainsail.

As for the use of laminates in the construction of furling mainsails, many are unsuitable due to the cloths vulnerability to UV damage and that is no good when sun can access the sail through the slot in the back of the mast. Laminates are also prone to mildew built up which can lead to problems when a sail is left rolled up within a confined space and delamination which can increase the risk of chafing when furling and unfurling.

Downwind Update

webcraft Expert Advice, Kemp News
Downwind Update from Kemp

Much has changed with downwind sails over the past 15 years or so. For cruising sailors it used to be a relatively simple choice between a spinnaker flown from a pole and a cruising chute tacked to the stemhead (or to a short bowsprit). Now there’s an array of lightweight asymmetric sails including, of course, the one everyone talks about: the Code 0 (though many sails described as Code 0s are really not Code 0s at all, as we will explain).

So what has happened, why has it happened and, most importantly, where does it leave you?

G-One on a Discovery 55 (Kemp Sails)
Photo: G-One on a Discovery 55 (Kemp Sails)

WHERE RACING LEADS…

As developments in cruising so often do, it all started with racing boats. About 20 years ago in the Whitbread (subsequently Volvo) race we witnessed the appearance of the Code 0: a large, lightweight, free-flying headsail rather like a flat-cut asymmetric spinnaker. It was designed to fill the gap between a conventional spinnaker and an upwind headsail – not so much a downwind sail as what you might call a “crosswind” sail.

These sails and their variants have since become popular across the racing world and in cruising circles too. Just bear in mind that many so-called Code 0s are not actually Code 0s because, under the IRC rating rule, a Code 0 has to have a mid-girth that’s 75% of its foot measurement. In practice that means a rounded luff that’s typically not attached to the torque rope of a furling system. Such a sail is more of a challenge to handle than many cruising sailors want.

There has, however, been an increasing need for cruising sails that fill the gap between upwind headsails and conventional spinnakers, and that’s largely because of changes in modern rigs. Back in the days of the IOR (international offshore rule, which influenced cruisers as well as racing yachts), boats tended to have relatively small mainsails and large foretriangles with overlapping genoas. More recently, for easier handling and inspired by racing rules since the end of the IOR, we have seen a move towards larger mainsails and smaller fore-triangles. Self-tacking headsails have become increasingly popular, too.

These changes have simplified handling, particularly upwind when much less winching is called for, but they have led to a problem. When you bear away from a close-hauled course and ease a small, close sheeting headsail, it twists open and loses most of its drive as well as progressively disappearing behind the mainsail. In light winds you will often be slower on a reach than upwind, yet unable to hoist a spinnaker or cruising chute until the wind is approaching, or abaft, the beam. This leaves a wide angle between a fetch and a broad reach when many modern cruisers feel rather lifeless. So what’s the answer?

MULTIPLE CHOICES…

Fundamentally the choices are the same as always: symmetrical and/or asymmetrical. It’s just that there’s now a far greater range of asymmetrics (sometimes known as A-Sails) to choose from, ranging from those that are essentially large, lightweight genoas all the way to full-cut asymmetrics for deep downwind angles. As you would expect, at Kemp we offer sails to cover the whole spectrum and we’ve given a lot of thought to what each sail should be designed to achieve. Even with all our expertise and experience, however, we have yet to come up with one sail that does everything. We will announce it as soon as we have changed some of the laws of physics! In the meantime, read on to see how we can make your downwind sailing fast, fun and trouble-free.

DOWNWIND AND CROSSWIND OPTIONS…

In ascending order of wind angle – from close to broad – below are the sails to choose from. But before we introduce them, a word about furling systems, which are often used to make handling these sails as simple as possible. Furling systems using torque ropes (otherwise known as anti-torsion cables)have played an essential role in making lightweight, free-flying asymmetric sails manageable by short-handed crews.

In many respects they’re like conventional furling systems for headsails, only they’re not connected to the forestay and, instead of an aluminium extrusion between the bottom drum and the top swivel, there’s a torque rope. When you turn the drum, the torque rope turns like a headfoil, without twisting, and the sail wraps around it. Another difference is that some of these downwind sails are not attached to the torque rope – just the tack to the drum and the head to the top swivel. There are also two types of furler: bottom-up and top-down, depending on whether a particular sail should be furled from the tack or the head. We supply both types as appropriate and, importantly, many components are common to both, so if you have multiple sails you won’t need to buy two complete furling systems.

Photo: Racing Asymmetric – A2 (Team Firefly)

1 | ULG
Usually made from 3oz polyester (as opposed to spinnaker nylon), the ULG has a straight luff and can be handled with a bottom-up furler or without any handling aids. It’s ideal when you’re cracked off the wind a few degrees and want to keep the boat powered up.

2. G-ZERO (GENNAKER)
Our G-Zero is similar to the ULG, also with a straight luff and the torque rope encapsulated in a luff sleeve for easy handling. Being designed for slightly broader angles, it’s made from nylon rather than polyester and incorporates more roach in the leech. Suitable for use with a bottom-up furler or a snuffer (or nothing at all if you prefer).

3 | G-ONE (CRUISING CHUTE)
This is the closest equivalent to what has commonly been known as a cruising chute and will help keep the boat moving as the wind comes further abaft the beam. Fuller cut than G-Zero, it’s made from spinnaker nylon and, if you have a furling system (top-down for this one), the luff won’t be attached to the torque rope. There’s also some round (positive roach) in the luff. A snuffer is an alternative handling aid with this sail.

4 | RACING ASYMMETRICS (A0–A5)
For racing sailors we offer the full range of racing asymmetrics, from the Code 0 (A0) to specialised reaching and running sails. Please ask for details.

5 | THE BUTTERFLY SAIL
With this option you have two sails in one. It consists of two ULGs sharing a luff rope. Use them folded together in the same way as a ULG or, with the wind from astern, spread your wings and open them up one each side. If you pole the windward one out, you can sail with the wind up to 15° off dead astern. Use with a bottom-up furler.

6 | SYMMETRIC SPINNAKERS
We’re listing this as a single option but, of course, there’s a whole host of choices for different wind strengths and points of sailing. These sails are still the most efficient solution for sailing deep downwind and running square, but they do call for a pole and a little more experience.
All downwind sails are a compromise and, as you can see, there’s quite a choice. ULGs and G-Zeros are the easiest to handle. If you’re going to have just one sail, we would suggest a G-Zero or a G-One. If your budget allows two, a ULG and a G-One would be a good combination. Bear in mind that, depending on conditions and how well they’re furled, you will often be able to hoist a ULG, G-Zero or G-One and leave it up for a day’s sailing with no need to drop and re-hoist each time you use it (though do bear in mind the greater susceptibility to UV degradation of these thinner fabrics).

AND FINALLY, LET’S NOT FORGET…

The magic, all-in-one downwind sail that does everything brilliantly. When we’ve invented this, we will supply it in a package with a dozen sky hooks to hang things from – and that’s a promise!