Making Ready 4 : making sail

 Stargazer's mainsail is the twelve year old original. It has outlived two jibs. But now it is beginning to lose its shape. The time has come to commission a replacement. There are three decisions to take : What sailcloth to use, what construction to employ and who to make it?

 The choice of sailcloth breaks down into three options: moulded, laminate or woven. 

Moulded sails were pioneered by North Sails, under the 3Di brand name. This process lays load bearing fibres, aligned along the stress paths of the sail, over a three dimensional mould. This mould is specific to the sail being produced and determines its 'flying' aerofoil shape. The web of fibres is locked into position with a flexible resin before being heat cured. The end result is a low stretch lightweight sail. Durability is superior to that of laminates, but (almost certainly) inferior to that of wovens. I say 'almost certainly' because this technology is relatively young. Stargazer's berth neighbour, Reefer X, a hard raced X-99, invested in a full suit of 3Di three years ago. I am watching their longevity with interest. Two downsides which are known with certainty are : high price; and that repairs and winter maintenance are a specialist matter. Requiring a trip to the single UK North loft, on the South Coast. 

Laminate sailcloth is the forerunner to one piece moulded sails. In a laminate, load bearing fibres are sandwiched between two layers of mylar scrim and then glued. A wear and ultraviolet (sunlight) resistant taffeta is then stuck to the outer surfaces of this core. The end result is a low stretch membrane, which is cut into panels and assembled into a sail. The weight is higher than that of a moulded sail. But then the cost is around a third lower. The achilles heel of laminates is durability. One of Stargazer's jibs was laminate. It set beautifully, right up to the point when, at three years old, it delaminated. An experience which I know to be typical. Minor damage, to laminate sails, can be readily repaired on board, or by a sailmaker. But once the glue fails, and 'hernias' (splits) appear in the Mylar scrim, 'all the king's horses and all the kings men. . . [cannot]. . . put Humpty together again.'

Woven sailcloth has its roots in the fabric panels which drove the Viking longships. Those were made of flax (low stretch but prone to rot and laborious to produce) or wool (rot resistant, but heavy and liable to stretch). Much progress has been made, over the subsequent millennia, in a quest for the sailmaker's holy grail. A cloth which combines: low stretch, high durability, light weight and affordability, 

Dacron has universally replaced natural yarns. It is what Stargazer's current main (pictured above, double reefed) is made from. Wovens score well on all parameters, bar stretch. Weight is similar to that of laminates. Cost is lower than either laminate or moulded. Even quite major repairs can be carried out by almost anyone, anywhere. So far as durability is concerned, a woven cloth is the least susceptible to damage, be that by abrasion, ultraviolet or flogging in the wind. However, vulnerability to stretch means that a woven sail’s flying shape is never as stable, as that of the two more modern technologies, and deteriorates further, as it ages. Although its failure mode is a loss shape, rather than disintegration. A significant advantage to a cruising boat on passage.

But a predisposition to stretch is a fundamental failing for a sailcloth. Fortunately, there is a family of  'twenty first century' woven sailcloths, which address the stability shortcomings of Dacron wovens, whilst retaining, in large part, their other benefits. This is through the inclusion of, ultra low stretch, Dynema fibres in the weave. Hydranet Radial (pictured above) is a proprietary Dacron based cloth, produced by Dimension Polyant, and stabilised, along the diagonal, with Dynema.  

 Vectran, now woven by three manufacturers (Dimension Polyant, Contender and Bainbridge), takes a similar approach, but is stabilised along the horizontal axis. Costs are nudging up toward those of laminate cloths. Physical durability is on a par with conventional wovens, or better. Shape stability is a little short of laminates, but far superior to that of Dacron wovens.. Weight is similar. Repairability is as good as for a standard woven.

 These cloths seem to me to be the sailcloth sweet spot for the cruising sailor. Stargazer's current jib (now five years old and still setting well) is in Hydranet Radial. 

One last question remains, before a decision, on cloth type for Stargazer's new mainsail, can be finalised: That of the sail's construction. This is because the different Dynema reinforced wovens are optimised for specific construction methods.

 Leaving aside one piece moulded sails, there are two constructions: 'radial' and 'crosscut.' This Falmouth Working Boat, beating majestically off her mooring, has a crosscut main and a radial jib. The terms referring to the panel layout.

Both constructions take panels of cloth (woven or laminate) and join them, to produce a sail with an aerofoil shape when hoisted. This three dimensional shape is created by cutting adjacent panels with a curve, to the edges along which they meet. The luff (front edge) of the resulting sail is also built with a curve. Thereby forcing more shape into the sail, when this elliptical edge is is attached to the straight(er) mast. (A crosscut sail is shown above).

Due to the more complex panel layout, of a radial cut sail (pictured above), more shape can be dialed into it, than into one that is crosscut. The two constructions also differ in how the loads within the sail are carried. Again, the radial sail has the advantage. Its panel design gives the sailmaker a greater ability to align the, low stretch, warp of the cloth with the load, so as to maximise stability. In terms of cost, crosscut construction regains some lost ground. With fewer seams and significantly less cloth wastage, a crosscut sail is typically three quarters of the price of an equivalent radial cut sail.

Stargazer's jib is high aspect ratio, like the Falmouth Working Boat's: tall, narrow, and highly loaded. Radial construction is therefore required. Hydranet Radial (as the name suggests) is optimised for this panel layout. It was therefore the clear choice. 

Stargazer's mainsail has a lower aspect ratio (is wider for its height). Additionally the sail is supported by, not only the mast and boom, but also by four full length battens. It is therefore subject to lower loadings, than the jib. These characteristics suit a crosscut construction, for which Vectran is optimised. 

All Vectrans are not created equal, however. The Dimension Polyant and Contender Vectrans look similar, with a 'pinstripe' of Dynema fibres running across the sail (see the picture above the Falmouth Working Boat). Whereas the Bainbridge HSX-V version of Vectran distributes the Dynema in a more even, 'rip-stop' (or grid), pattern (picture above). To my mind, this offers the potential for greater panel stability. Decisions one and two are made: Stargazer's new main will be of crosscut construction in Bainbridge HSX-V.

That leaves decision number three. Who is to make Stargazer's new sail?  This project has been eighteen months in gestation. Giving plenty of opportunity to ponder the options, and to visit lofts, whilst Stargazer has cruised. My shortlist includes: an internationally reputed 'big name,' a nationally known loft, and a Kent based artisan sailmaker.

 I contact North Sails. Head quartered in the USA, and represented around the globe, this is probably the most prestigious, and technically innovative, sail brand in the world. Perhaps unsurprisingly, they prove something of a corporate juggernaut to deal with. There is very much a North process, to which a customer must conform, in order to proceed with order placement. One of my great joys, in retirement, is the freedom from any whiff of compliance with corporate whim. Making this a travelator on which I am reluctant to embark.  I am also deterred by the discovery that North sails are made, out of sight, offshore, in (low wage?) Sri-Lanka. Although, naturally, they come with a considerable price premium. After all, North has, legitimately, to recover their investment in technical research and brand marketing. Maybe, were I in the market for a suit of 3Di, selecting North would be worth these compromises. But not for, more widely available, panel built woven sails. 

Whilst on Stargazer's 'Out of Lockdown' shakedown cruise, I visit OneSails on the Orwell. Sailmaker to Pip Hare's 2019 Vendee Globe campaign. Over coffee, loft manager Brian asks me all the right questions. He offers candid advice too: "Glue and string' (laminate and moulded) sails don't have the durability for your needs. . . . . .Look, I can build you a lovely crosscut main. But I can build you a beautiful radial main. . . . . .Only you can decide if its worth the extra. . . . . ." Sails are made on the premises. OneSails, through their sister company Evolution Rigging, could also take on the replacement of Stargazer's standing and running rigging. Although this would require her to over winter ninety (road) miles away, across the infamous Dartford Crossing, in Suffolk. 

Alan and Sarah, of Wilkinson Sails provide the artisan option. They have demonstrated a high level of support, since Stargazer moved to Chatham. Carrying out running repairs, winter sails valeting and replacing Stargazer’s sprayhood, with one of an ingeniously improved design. We discuss options, whilst Stargazer is back in Chatham, and I await my second covid jab, before departing for Scilly. Delving into the minutiae of cringle and batten box designs, the most suitable batten cross sections; as well as matters of cloth and construction . Alan, cuts sails on the varnished wooden floor of his loft, at the head of Faversham Creek. It transpires that he could pick up Stargazer's rigging work, if I were willing to have her lifted during his winter slack period. Our conversation continues by e mail, as Stargazer sails south. By the time we drop anchor in the Helford river, Wilkinson Sails has our order.

Footnote: To discover more, about the Viking Longships, click here to reach the website of the Viking Ship Museum, in Roskilde, Denmark. It describes how the museum has reconstructed, and sailed, Viking (trading and war) craft, in their mission to shed light, on the achievements and sophistication, of the seafaring civilisation which built them. 

Picture Credits:

1,5,8,12,13,15    Me

2                         North Sails

3,14                    OneSails

4                         Roskilde Viking Ship Museum

6,7                      Dimension-Polyant

9,10                    Challenge Sailcloth

11                       Bainbridge