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Wave Sails On Test (2008)

14:12 12th May 2010 by Ed Davis
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The BOARDS Test Teamput a selection of wave and all-round sails through their paces in asmany different sizes as possible, while also exploring how each reacts to different brands of mast. Pix by Andy Joswik…

Continuing with our sail testing approach of the last few seasons, rather than simply trying one size in a range (which may be the ‘sweet spot’, or indeed the worst sail in that range!) our aim with this test was to test each range in as many different sizes as we could, utilising the facilities of OTC in Tenerife where several sizes of most ranges of wave sail are available all rigged on the correct masts. Unfortunately, the wind didn’t quite play ball so we were only able to test each sail in a couple of sizes, but it still helps to give a much broader and more accurate picture than looking at just one size only. It tended to be the 5.3 and 5.7m sails that got the bulk of use. However, there are various ranges – like our quiver Tushingham Rock 4.7s, Gaastra Poison 4.0s and Manic 5.0s – that we have used in other sizes over the course of the season. We also rigged many of the sails on a variety of different masts, to assess the setting effect of different mast types.

We’ll keep the pre-amble down to a minimum, as there’s not actually a great deal to say. This is a relatively stable area of the market – sails of this size and style in general work very well. The designers are clearly comfortable with what they are doing, and most are continuing to do it with just little tweaks to planshape and foil from season to season. (Last year’s ‘designer reshuffle’ between the brands is now working its way through to the shop shelves, with most designers clearly nudging their new models in the directions that they favoured under their previous banners.) Indeed, the main observation is that over the last few seasons, it has been very noticeable that the gaps have closed significantly: while the best have been improving only marginally (if at all), the dogs from a few years ago have come on in leaps and bounds, squeezing the range of overall quality on offer into a much tighter band with far less to choose between the best and worst.

Because of this we’re not going to choose any favourites this year. On the basis of this test you are extremely unlikely to buy a 4.5 to 5.3m wave sail that you won’t quickly get used to and learn to like. For sure there are differences of style, and there are still sails that we would clearly prefer over others, but they all work pretty well over a decent wind range. We found a bit more variation in quality in the bigger (5.7m) sails and smaller (4.0/4.2m) sails we tried, since some small wave sails can become too twitchy and some big wave sails a bit unstable, but most still fared pretty well.

SKINNY vs STANDARD:

Last year we did extensive testing using pairs of matched sails with both standar diameter (SD) and skinny / reduced diameter (RD) masts and our findings were pretty conclusive. In nearly every case best performance was achieved using a skinny. Although we are aware that there is a body of opinion still opposed to this view our overwhelming experience has been that both feel and speed / acceleration are nearly always better with a skinny. Top end stability may not be quite as good but this hasn’t presented as much of an issue. Our advice would be to explore the possibility of using skinny masts with wave sails unless you have very good reason to do otherwise. Ironically, this advice has much more to do with the gains in feel and performance than strength. It seems that most mast manufacturers are now making skinnies not much stronger than equivalent SD masts. This is presumably because any mast will be both cheaper and feel lighter and more responsive if less material is used to beef up the thickness of its walls!

Another reason that we’re holding off from making recommendations is because our perception of sails has changed so massively over the past year or so, now we’ve realised just how much the performance of the entire rig is attributable to the mast. No longer can we simply be happy testing a sail with one mast even if it is the manufacturer’s recommended one. Many sails, though perfectly useable as they are, set clearly better with different masts. It is a real shame we couldn’t do more testing on this because we now know what a huge difference it can make. Future tests will concentrate more on this aspect – although, of course, the recommended mast still has to be our obvious starting point.

bald man getting rad

DIFFERENT MASTS:

We rigged as many of the sails as we could on as many different masts as we could, and we’ve discussed in detail our findings in the test write-ups. So here’s a more general explanation of how a different bend curve and stiffness of mast will effect the set of a sail.

Stiffness:

Mast stiffness has a big effect on sail performance. Contrary to popular belief not all 400 masts are the 19 IMCS stiffness that they (virtually all) quote. If you look at the Mast Directory you will see that they vary between about 18 and 23 This is considerable variation. If your sail feels too soft, flexible and unstable try and find a stiffer mast for it, if it feels too hard, stiff, twitchy and unresponsive try a softer one.

Too stiff a mast:

The sail is harder to downhaul and outhaul, making the foil tighter with a lot less give or flex. It consequently reacts less to the wind, generating less power in lighter winds even though it may well force a bit more fullness into the luff. Overall a sail rigged on too stiff a mast will feel overly taut and twitchy and unresponsive, a bit powerless in marginal winds, and not quick enough to release power in stronger winds.

Too soft a mast:

The sail will be too quick to derotate on the luff and twist away at the leech. Although it will feel a bit more responsive in very light winds it won’t hold its shape through a decent wind range and will distort too easily.

An easy way to compare:

In every sail range there are sizes with luff lengths near the break point between one size of mast and another (e.g. 400cm, 430cm). A typical 5.3m sail might have a luff of around 430cm, and may be recommended for use with either a 400 mast with a 30cm extension or a 430 mast with no extension. Longer masts are usually stiffer than shorter masts, so if you have both a 400 and 430 mast (of the same range, otherwise you’re throwing a whole heap of other variables into the picture!) you can experiment with each to compare how mast stiffness affects your rig. We often find that actually the softer (shorter) or stiffer (longer) mast works better than the recommended size. If you have a short adjustable head (or don’t mind a 10cm gap between sail foot and mastfoot) and/or have a long (40cm) extension you could exchange masts between sails with luff lengths 10cm either side of 430 to see if changing the stiffness improves performance. Experimentation is well worthwhile, since it really can make quite a major difference to your rig for no additional financial outlay! The same can be tried with sails of luff lengths within 10cm of 400 or 460cm (i.e. usually around 4.2 or 6.3m). Bear in mind that what works for one person may not necessarily work for another though; as a general rule heavier sailors tend to like stiffer masts than lighter sailors because they tend to use a given size of sail in stronger winds.

Bend curve:

IMCS bend curves are explained in the Mast Directory elsewhere in this issue. It is not a perfect system for describing the bend of masts but it is OK (and it’s all we have). However, due to the difficulties of getting exact measurements and the variation between masts even of the same type, it’s pointless to try to be too precise with it. For practical purposes with wave sails we think of masts as either ‘stiff-top’, ‘average’ bend curve or ‘flex-top’. Most masts from a given brand tend towards one of these classifications. Thus Pryde and North tend towards flex-top, while Gaastra and Maui Sails use much stiffer-top bend curves (often better thought of as softer in the mid section) and lofts like Simmer appear to use average bend curves.

filler

You might think that the safe advice to anyone buying an accessory mast would simply be to match the bend curve to the masts recommended by the sailmaker. In practice we have not always found this to be the case. Sometimes performance can be significantly improved by using a softer or stiffer top mast than recommended. We appreciate that without specific details this information is of no practical use to anyone planning a purchase, but the underlying point is still an important one to take on board: you cannot assume that the bend curve of a manufacturer’s recommended mast is actually the best one for that sail. So don’t be afraid to experiment, even with masts very different to what the manufacturer recommends. In some instances it can be very important to use either quite a distinctly more stiff-top or flex-top mast to make a sail work OK.

(Note: For the purposes of this article we are talking about masts of 400cm length and for wave sails. The effect of bend curve can be more exaggerated with larger sails, particularly if they have inducers.)

Too flex-top a mast: For example setting a Gaastra Manic on a Pryde mast:

• The leech goes too floppy at the head.

• Meanwhile the luff stays exaggeratedly rotated (battens sticking too far round towards the front of the mast).

• The sail seems to need stacks of outhaul to set properly and this over-tightens the foil in the body of the sail.

• In use the sail will flap and release at the head while the body stays too stiff and rotated. It will tend to have good top end and stability, at the expense of low end power. The centre of effort will tend to stay too far forward.

Too stiff-top a mast: For example setting a North Ice on a Maui Sails mast:

• The head stays relatively untwisted.

• The rotation comes out of the sail too easily (battens pull right away from the mast before there is enough tension in the sail) leaving the body either too flat or too soft.

• The sail will require minimal or no outhaul.

• In use the sail will have a tight leech and soft mid section, thus feeling more responsive in lighter winds but losing stability quickly. Release off the upper leech will be compromised and the centre of effort will tend to stray too far back.

cruisin'

ABOUT THE TEST:

The test was carried out at the OTC in Médano, Tenerife where most of the sails in this test (plus others that aren’t), are available for anyone to hire and try out. We tried all the available ranges that we had the time and conditions to use. (Unfortunately we are unable to review Loft or Severne Sails at the moment as their UK importer will not make them available to us for test as a result of disagreements about past test findings.)

We would like to thank all the staff at OTC for their help as well as Tushingham for the loan of their narrow-diameter Aeron CT booms, and North for help with their on-the-water-adjustable XT extensions.

THE TEAM…

Ian Leonard, Emile Kott, Jono Dunnett, Mariusz Golinski, with important input from Tris Best and the staff at OTC.