Rating optimisation for IRC - some basic tips

Over the course of any season, in yacht club bars the length and breadth of the country boat owners and crew can be found exhaustively discussing ways to improve the rating of a given boat, particularly at this time of year when the season is over for most people and everyone's had a chance to reflect on what might have been.  For most people optimising the rating means driving the rating down and for some this can be something of an all encompassing ongoing quest. However, reducing the rating isn’t necessarily the best thing to do. Let’s just consider what we mean by optimisation:

"Optimisation" is the act of balancing a set of variables such that the detrimental effects of each variable are minimized while maximizing the beneficial aspects of each variable.

In other words, optimising the rating could mean that the rating goes up in order to strike the right balance between the salient variables. If the rating goes up by 2% but the boat goes 3% faster then clearly that is a good thing! This article is not concerned with the kind of intricate and complex optimisation that might be found on a TP52 programme, rather the kinds of things that the everyday club/regatta boat might consider. Following are a couple of examples of the kinds of typical conversations that we have with owners on a regular basis.

Firstly, there is the owner of a boat with overlapping headsails who wants to reduce their rating by re-rating their boat with just their No.3 jib. It’s pretty easy in principle, reducing the sail area will reduce the rating. But the boat will go slower, don’t ever forget that! There are several potential problems with this sort of argument. Most ‘modern’ boats are designed with non-overlapping headsails from the outset and they will typically have 2 or 3 ‘Coded’ Jibs that are all virtually the same size but which are designed to have different flying shapes to accommodate different wind ranges from zero wind upwards. The owner that wants to ‘re-rate with a No.3’ is forgetting that this is a sail that he would usually use in stronger winds and it is therefore not suited to be used further down the wind range because it is too heavy and too flat. So, rating the boat with the token No.3 will require the purchase of at least one more sail that is designed specifically to accommodate lower wind speeds.

This approach also ignores the fact that the boat was originally designed with large headsails for a reason; it needs the horsepower! Reducing sail area is likely to leave the boat horribly short of power in lighter winds and it will therefore struggle to be competitive. There are mitigating circumstances of course. If you tend to sail in an area where the breeze rarely drops below say 12 knots then you would argue that this is sensible optimisation as you might not spend much time sailing around with the overlapping genoas anyway so there’s no point in sailing around with the extra rating. These points are generalisations of course; some boats will be more suited to the idea than others. With sufficient budget and technical capability you could work out what was likely to work and what wasn’t. However that is outside of the remit of most people so your best clues will likely come from looking at what similar boats have done and how successful they are as a consequence.

The second popular talking point concerns spinnaker area. In general, IRC seems to encourage higher areas than what would have been considered the norm a few years ago, particularly in small to medium sized boats where light displacement is discouraged. Increasing downwind sail area seems to provide a good trade off between rating and performance. In other words, spinnaker area seems to be relatively cheap in terms of rating. However, care must be taken; carrying more spinnaker area is going to be beneficial in lighter airs but if the boat becomes unmanageable in even moderate conditions (something that we see only too often) then the boat ends up sailing a disproportionate amount of time rated for a spinnaker area that it cant use.

From just looking at these two examples it is pretty clear that there are many things to think about and some of them may not be that obvious from the outset. In optimising the rating it is important therefore to consider a number of different things:

·       The type of sailing you are planning on doing

·       The likely conditions that you are likely to encounter

·       The boats that you are likely to be sailing against

·       It is generally advantageous to be one of the highest rated boats in a given class so there may be a case of artificially reducing the rating via sail area (within limits) in order to sail in the next class down

·       Likewise you might want to increase your rating via sail area in order to get you towards the top end of the rating band if that means that you are sailing in clean air more readily.

·       Consider manageability; for example, if you find yourself regularly short tacking against the tide then the ease of tacking a smaller non-overlapping headsail might outweigh the decrements associated with having a slower boat.

·       The characteristics of the boat itself; extra sail area won’t increase a displacement boats ‘hull speed’ but it will however help the boat to achieve its hull speed more readily and improve its average speed. It won’t however turn a displacement boat into a planing boat.

·       In addition make sure that your sails are re-measured regularly. Laminate sails shrink as they age and this is often enough to save a point or two.

Please feel free to give us a call to discuss what might work for you…..

Preparing your sails for winter

As we approach the time of the year when most people are thinking about laying-up their boats for the winter it is important to give some thought to your sails. All too often we see furling genoas being left up all winter whilst the boat is ashore; the same goes for mainsails that are left on underneath their sail covers. This of course means that the sails are at the mercy of the elements for extended periods of time; not only that but the tightly bound and folded sails combined with a damp salty environment become perfect breeding grounds for mould and mildew. We strongly recommend therefore that if the boat is out of use for any period of time, especially over what can be a long and harsh winter at the very least they should be unbent and stored somewhere dry. If you are in a position to rinse and dry the sails yourself and inspect them closely prior to folding them away that’s great but if not we are happy to take care of the whole process for you.

Sail repairs and service by professionals

Regular maintenance of your sails by skilled sailmakers can significantly enhance their working life, saving money for the owner and ensuring reliability when it is needed most. Sails operate in a hostile environment where sail and pollutants can cause serious damage to even the best kept sails. Similarly, constant wear & tear requires careful repair and maintenance with an end of season overhaul being essential for the longevity of your sail wardrobe. It is important that any damage, no matter how small is repaired as quickly as possible in order to prevent further damage occurring.

Recuts and retrofits

A simple recut can improve shape and give a new lease of life to a ‘tired’ sail. With improved shape comes improved performance and handling, something that is well worth thinking about whilst the sail is off the boat anyway. Retrofit extras include UV protection, luff flatteners for shape retention when genoas are partially furled, changing from hanks to luff foils, altering batten configurations, adding reefs to mainsails etc.

Sail Laundry

OneSails recommend that any sails that are salty or damp get sent to a sail laundry prior to winter storage. The laundry process will remove any salt and any other airborne pollutants which may harm the sails if left for any period of time. This in turn helps to prolong the overall life of the sail. It also has the added benefit of making the sails easier to work on if any service work is required, and means that they will be dry when they are put away for the winter. If they are put away whilst damp, they are more likely to attract mould or mildew and will not be in a pleasant state when you come to bend them back on next season.

The specialist sail laundries are essentially large warehouse type buildings. The sails are cleaned by a variety of processes. A few older sails that have either gone soft with age or which have a soft feel by design get washed in large industrial washing machines. There is very little (if any) in the way of detergents or bleaches that gets added at this stage, the sails are simply rinsed to remove any salt. The vast majority of sails and in particular racing sails don’t go into the machines. They are laid flat on a smooth concrete floor and hosed down with fresh water from a pressure washer with a special attachment. Whilst the sail is on the floor any spot cleaning is done to remove any green algae, mildew, grease etc. At this stage some chemicals such as mild detergent solutions will be used where necessary. If chemicals have been used, the sails are then rinsed again. Once the sails have been cleaned they are then hung up to dry before being folded and returned to the sailmaker.

Whilst we highly recommend sail laundry for any sails that are being stored for any length of time, the process does have certain limitations. Although the sails will be returned from the laundry dry, salt free and in an ideal state to be worked on or stored, the process is not a cure all that will leave the sails looking ‘as good as new’. Stains such as mildew, grease and rust may be removed if they are treated straight away but will stain the sail permanently if left for any period of time. Other typical stains are from diesel or machine oil. These cannot be removed fully and will always leave a stain though laundering them will remove any smell and surface residue. It should also be noted that there is no guarantee that stains including mildew, mould or rust will be removed during the laundry process.

At OneSails GBR we are pleased to be able to offer a full range of sail repair and maintenance services, please feel free to contact us to see what we can do for you and how we can help to extend the life of your sails. 

4T Forte - One piece composite sails for racing & cruising

In 2007, OneSails introduced the first continuous fibre sails built without the use of resin or glue, eliminating delamination issues at a stroke. Now OneSails goes a step further, by introducing 4T FORTE™ membranes made from exclusive Multi Micro Structure (MMS™) technology (patent pending).

The 4T FORTE™ composite structure incorporates high modulus fibres such as STR Solid Stripes, a new low stretch component of MMS™ technology which eliminates both glue and the mylar film, so often the weak element of a laminate sail. Using a multi micro layered structure, elements of the membrane are fused together in a cross linked, polymerised matrix resulting in a stable, stretch resistant, and durable sail. By doing away with both glue and mylar film these sails are significantly lighter than conventional laminate sails. Not only is 4T FORTE™ intrinsically lighter than alternatives, but weight saving is enhanced by the fact that a 4T FORTE™ membrane does not need to be covered with extra woven taffeta fabric to protect it from UV or improve durability. Using components derived from recent developments for the military and biomedical science, MMS™ technology provides a robust and reliable sail skin, manufactured with the minimum of environmental impact and allowing realistic recycling options. Since glues, resins, and solvents have been replaced by heat activated fusion and the base polymer is 100% recyclable in a standard waste separation process, 4T FORTE™ sails can claim to be truly "green sails".

Multi Micro Structure (MMS™)  technology represents a leap forward in the production of sail material, leaving traditional mylar based laminates in its wake. A core structural grid, constructed from high modulus fibre takes care of the principal loads, whilst oriented micro layers provide strength in other secondary directions. The entire skin is encapsulated between ripstop "shields", which are UV, moisture, and mildew resistant. The whole skin, with its continuous fibres, is vacuum cured in a heat activated cross polymerisation process. which fuses the components together so that every single element in the structure contributes to shape holding. As a result, a 4T FORTE™ sail membrane not only exhibits superior structural integrity, but the use of more efficient components creates a sail up to 25% lighter than film based alternatives.

Thermo Moulded Sails

Unlike most of the membranes in the market that are built with the use of resins or glue, 4T FORTE™ membranes are made by a vacuum cured heat-activated cross polymerisation process. This ‘thermo moulding’ technology ensures superior structural integrity with no extra weight in the way of adhesives added to the sail. The cohesion of the different layers that create the flexible composite is obtained through the vacuum fusion of the thermoplastic elements which is why adhesives are not necessary. An added advantage of this process is that because no resins or glues are involved delamination is not possible and this term is therefore inappropriate with regards to 4T FORTE™.

STR Solid Stripes

For many years carbon has been the ultimate and dominant fibre in performance sailmaking. In 4T FORTE™ OneSails has instead introduced ‘STR Solid Stripes’ which have a better strength/weight ratio than carbon and a huge number of other advantages including being more robust, having higher tenacity and a full resistance to the harsh factors of the marine environment such as UV, temperature and moisture. These latest generation polymers have been developed relatively recently using a truly innovative synthesis processes. They are characterized by low specific weight and very simple chemical chains that are linked and rigid and which resist deformation by various aggressive spoiling agents.

STR Solid Stripes are similar to other products used in sailmaking such as Dyneema and Spectra, but they should be regarded as entirely distinct because they are not subject to the same kinds of issues such as shrinkage and creep. Moreover, they do not exist in the form of bundles of microfilaments, but as 'stripes' or thin homogeneous ribbons, presenting a significant contact surface and enhanced cohesion in the multi-layered microstructure within which it integrates perfectly.

As a consequence of the enhanced properties of these flexible composites, there will be a shift away from regarding racing sails as ‘disposable’ as 4T FORTE™  sails will be more durable with improved performance and better shape stability. In the cruising market the impact will be even bigger because it will be possible to have sails that last well, but which at the same time are lightweight, soft, dimensionally stable and with an attractive appearance.

Because 4T FORTE™ is a multilayer composite it can consequently be produced in many configurations with the modular style of construction lending itself to adaptation to meet the requirments of different end uses and budgets. At present the entry level version features structural yarns of Twaron with the next level featuring STR Solid Stripes. The premium version features a higher modulus version of STR Solid Stripes for larger boats and instances where performance cannot be compromised. The cruising variants of these three options feature a robust outer skin which offers enhanced UV, moisture & mildew resistance without the need for a heavy taffeta layer.

Code Zero's for racing and cruising

Many modern yachts whether they are designed for racing or cruising tend to be equipped with reduced area or non-overlapping headsails that are very convenient and easy to handle but unfortunately make light air sailing, particularly when just off the breeze very slow and tedious. This is perhaps more of an issue on cruising boats where the single furling headsail will be a lot heavier than the equivalent found on a race boat. Even in more traditional boats with large overlapping genoas the sails tend to be so heavy that in light airs they just sag and do very little. A Code Zero (racing) or FFR (cruising) is the ideal solution for the discerning sailor who wants to maximise the yachts potential in light airs and have more control at wider angles as the breeze builds.

A Code Zero for racing purposes under IRC has to rate as a spinnaker which places restrictions on the geometry of the sail; essentially its mid with must be wider than 75% of the foot width. This in turn places constraints on how flat the sail can be.

The OneSails FFR (flat furlable reacher) is a cruising version of the Code Zero. Because it isn’t constrained by any racing rules they are actually more efficient at closer angles to the wind than their race oriented cousins.

Both the Code Zero and the FFR are considerably flatter and smaller than their downwind oriented counterparts. The tack of the sail is usually attached to a point just forward of the base of the forestay or perhaps to a short bowsprit or prodder. There is plenty of precedent however, particularly on cruising boats for them to be tacked to a strong point just behind the forestay and set on a short strop so that the sail is set clear of the guardwires.  They are designed to be flown with a taut luff which enables them to be used with a dedicated free flying furling unit which in turn makes them relatively easy to hoist and drop though many racing boats will choose to launch them in the same way as a conventional spinnaker. Both sails are usually constructed from a dedicated ‘Code-Zero’ style laminate though on smaller boats ripstop Nylon is often used as a less price sensitive alternative.

Both the Code Zero and the FFR can be thought of as very versatile sails. Although they are designed primarily as close winded sails they can be used in other ways too. In less than around 5 knots TWS it is possible to sail as close as 50 degrees TWA which is pretty well as close as the boat would sail with its regular headsail. The difference is that the sail is bigger and lighter so the boat performs better. As the breeze builds the sail is used at wider angles as the luff begins to sag and the boat starts to get powered up. In 10 knots TWS the sail would typically be used on a beam reach when the boat would be underpowered with the regular jib but overpowered with a full sized spinnaker. The same principles apply as the breeze builds further; the sail gets used at wider angles down to a maximum TWA of around 130 degrees but by this time a dedicated downwind oriented sail would probably be more stable.

In summary they are practical, easy to handle sails whose all round versatility makes them a welcome addition to most sail inventories, regardless of the end use, racing or cruising. 

Quotes:

Just a quick note to tell you how pleased I am with the new FFR that you made for Albatross (She 36). It has transformed our light air sailing which was evident with reduced fuel bills on our recent cruise to La Rochelle in hot weather with little wind. It helps that it is so easily handled with the furler so it can be set or furled on a whim. On the leg from Ile d'Yeu to Ile de Re we were getting 7+knots with a 9 knot beam wind - magic - especially as it was faster than the engine would have given us....! (Richard B, Hamble)

The Code Zero was the secret weapon (at Giraglia 2013). It had a much better range than I had expected and was extensively used. So thank you for making it at such short notice....(Mike G, Swan 56)

Contemporary Construction Types in Sailmaking

It is fair to say that sailmaking has probably changed more in the last 15 years or so than at any time in the past. Buying new sails can be something of a bewildering experience; speak to 3 or 4 different sailmakers and you could easily end up with what appears to be literally dozens of different options to choose from. However, a little knowledge can simplify the process considerably. The aim of this article is to provide a brief account of the three generic construction types that most sailmakers would currently offer.

Cross-Cut. In most instances cross-cut sails, where the panels run roughly horizontally across the sail would be made from woven Polyester, commonly known as Dacron. These are traditionally associated with cruising boats but are also commonplace on many smaller race boats and of course on dinghies.

  

Dacron sails are woven in the age old way on a special loom and have fibres running in a ‘warp’ and a ‘weft’ (fill) direction. The warp fibres run in a continuous length along the roll whilst the fill fibres run perpendicular to the warp, i.e. directly across the roll. It is possible to vary the quality and size of the fibres as well as the density of the weave and this in turn results in Dacron’s with different properties. In fact all of the cloth manufacturers offer many different styles of Dacron, each of which is suited to a different end use or budget. This is covered in more detail in a separate article.

Dacron fabrics tend to be much stronger in the ‘fill’ direction than the ‘warp’ direction which is why they are used in cross-cut applications; the fill fibres are lined up so that they correspond with the chord between head and clew which is roughly the direction of maximum load in the sail (see the red line in the picture above right). However, this depiction of the loads in the sail is rather simplistic as there are additional loads running in many other directions that are not particularly well catered for by simple woven fabrics.

Radial Cut. In order to cater for the myriad of loads present in a sail, the sailcloth manufacturers developed cloths that were stronger in the warp direction than the fill direction (opposite to Dacron) and which also had better properties in the ‘bias’ (45 degree) direction. By using these cloths in a tri-radial panel orientation more of the loads in the sail could be supported. The resulting improvement to shape stability means better performance. It is important to note that this is as important to the cruising sailor as the racing sailor as better shape retention equates to less heeling, less flogging and better handling. In the graphic on the right it is easy to see how the loads in the sail (red and blue lines) are more effectively taken up by the radial panel orientation than the cross cut one.

The cloths themselves are usually laminates featuring load bearing fibres sandwiched between clear Mylar films. There are a variety of fibre types used including Polyester, Pentex, Twaron, Technora, Dyneema and Carbon, each of which would be more or less suited to a particular size of boat, budget and end use. Adding a single or double sided taffeta backing to the fabric makes them more durable (though heavier) and therefore better suited to cruising.

Membrane constructions. This effectively refers to sails that are made from their base components upwards rather than cut from cloth that is on a roll. They are completely custom products in that typically each panel of the sail is laminated individually with a custom complex fibre map that is designed with the particular boat and end use in mind. The panels are then joined together to create one homogenous structure. The resulting fibre arrays more closely mimic the anticipated sailing loads than even the tri radial sails offering further improvements to shape stability and hence performance. Although these membrane sails were initially used solely on race boats, they are now increasingly commonplace on cruising boats of all shapes and sizes as improvements to technology and construction methods have reduced costs and added to their durability making them very cost effective alternatives to their radial cut counterparts. The photo above shows a membrane panel part-way through its lamination process, note the complex fibre array.

Broadly speaking, whatever it is that you are looking to buy (or whatever it is that your sailmaker is trying to sell you) will fall into one of these three construction types, regardless of whatever name the sailmaker has given it. There are of course some exceptions; some laminates are suited to cross cut constructions and it is possible to produce some woven cloths that are suited to radial cut applications. Similarly, many sailmakers will have their own slightly different methodology for constructing their membrane sails though essentially the principles remain the same. It wasn’t that long ago that laminate sails were the exclusive domain of the racing sailor but nowadays laminates including membranes featuring high tech fibres such as Carbon Fibre are routinely found on cruising boats. Next time you are looking to buy new sails don’t be afraid to explore the various options to find out what really is best for you….



Top tips for sail trimming....

This aim of this article is to help you to develop a better understanding of how to get the best from your sails. As with all trim and tuning guides, this is just that, a guide. This information should not be taken as absolute. It is impossible to sail strictly by the numbers. Trim and tune are dynamic, requiring constant changes to get the most from the boat. It is more important to understand the concepts behind tuning, and the effects of the different controls so that you can learn how to shift gears. Keep an open mind and experiment in changing conditions to determine the right combination for the moment, or simply what works for your sailing style. There is no one way to make your boat go fast. The single most important thing is to recognise when you are slow and to do something about it.

Rig Tune and Basic Set Up – Fractional rig with swept back spreaders

There are three goals to achieve in basic set up:

·         Centre the mast in the middle of the boat and ensure that the mast is in column athwartships

·         Set the correct amount of pre-bend for the conditions.

·         Have the correct headstay tension for the conditions

Forestay tension and mastbend are the key variables in adapting the rig setup to specific conditions. As with all fractional rigs with swept back spreaders, forestay tension is directly related to shroud tension. The tighter the overall rig, (uppers and lowers), the greater the headstay tension. The other principle to remember is that we want more pre-bend in light air, and less and less as the breeze increases. By starting off with less pre-bend, the mast will not ‘over bend’ when the backstay is pulled on hard. Conversely, in light air we want headstay sag and do not want to be using too much backstay to get the mainsail set up properly, so more pre-bend is desirable. Having a readily adjustable forestay is key to rapid changes of rig tune. With these points in mind, we recommend the following initial set up procedure.

1.       Step the mast and fit the chocks at the partners as appropriate.

2.       Make up all the standing rigging so that it is hand tight.

3.       Centre the mast. Pull the main halyard down to the toerail abreast the chainplates and cleat off. The halyard can then be used to measure to the toerail on the other side of the boat so as to check that the mast is upright in the boat.

4.       Wind on the cap shrouds gradually, winding an even number of turns on each side to the point where you might expect the leeward shroud to be just tight when sailing to windward in a force 3. (It is easier to tension the caps if you bend the mast using the backstay or runners on a boat with swept back spreaders). Now release the backstay.

5.       Wind on the upper diagonals to the point where they are a few turns beyond hand tight, but they should not be excessively tight. Check that the mast is still in column sideways by sighting up the luff groove from the tack position.

6.       Wind up the lower diagonals evenly side to side which will straighten the lower section of the mast. These should be wound on until the overall pre-bend in the mast is suited to the luff curve in the mainsail. Check with your sailmaker if you have any doubts as to how much bend should be in the mast. If you find that excessive tension on the lowers still results in too much pre bend then the mast heel will need moving forwards slightly. Likewise, if you can’ achieve enough pre-bend then try moving the mast heel aft slightly which has the effect of bending the mast around the deck partners.

7.       Again check that the mast is still straight sideways.

8.       Go sailing and check that the spar bends uniformly both fore and aft and sideways, also that the leeward shroud behaves as in 4 above

Note: Once the mast has been set upright in the boat (section 4 above), always add an equal number of turns to port and starboard in subsequent steps. The only exception to this rule is if the diagonals need adjusting to bring the spar back into column.

Pre-bend and mainsail shape

Mainsail shape and conditions will dictate final rig tension. If the mainsail flattens out too quickly (characterised by overbend wrinkles running diagonally from clew to mid-mast), then you need tighter lowers and/or a shorter headstay to reduce bend and make the mainsail fuller. In heavy air you should be able to pull the backstay all the way on just before the overbend wrinkles appear.

If the mainsail is too full for the amount of backstay being used, as characterised by excessive backwinding, or a sail which is ‘knuckled’ and excessively round at the front, less lower tension and/or a longer headstay is necessary. Once the mast has been set with the correct forestay length and shroud tensions for medium air, these should be regarded as ‘base’ settings. In light air decrease the tension on the lowers and add headstay length to induce additional pre-bend. Extra pre-bend and softer rig tension will also increase headstay sag creating more power in the genoa, which will also make it easier for the helmsman to ‘feel’ the boat and stay in the groove.

The uppers (cap shrouds) should not need to be adjusted providing you have an adjustable forestay. The upper diagonals (D2’s) again should not need to be adjusted, but bear in mind that these also act as a control for mast bend. If the sail is too full in the upper sections, they may be too tight, and vice versa.

As a general guideline, in light airs ease the overall rig tension on the forestay and/or decrease the tension on the lowers to induce additional pre-bend. As the breeze builds, increase the overall rig tension to prevent the mast from overbending as the backstay is pulled on. You should aim to create a tuning grid similar to the example below.

	0-7 knots	8-15 knots	16-22 knots	23+ knots
Lower Tension	Ease 1 turn	Base	Base	Tighten 2 turns
Forestay Tension	Ease 5-8 turns	Base	Tighten 5 turns	Tighten 8 turns from base

Upwind Trim: Headsails

Most race boats will carry at least 2 headsails to cover the wind range but some boats will certainly carry 3 or 4. On modern boats with non-overlapping rigs the Code 1, Code 2 and Code 3 Jibs will all be more or less the same size. They will however differ considerably in shape and weight. On a more traditional boat with overlapping headsails the differences are a little more obvious as the sails will differ in area quite considerably from one another. Within this guide I will not endeavour to provide tips for each sail, but will consider the basic tools that the trimmer has at his disposal for any headsail.

Increasing halyard tension pulls the
camber in the sail forwards

1.        Halyard: The basic rule is to use enough halyard tension to just smooth out the wrinkles in the luff. In light airs it is better to have slightly too little tension than too much. This makes the entry finer which will help with pointing, and will also power up the back of the sail. As the breeze increases, you need to use more halyard tension. This will round up the entry which makes the steering groove wider, and will also flatten the exit of the sail, which in turn de-powers it. Care should be taken with the No.3 jib as insufficient halyard tension and/or excessive forestay sag will result in the sail being ‘too round’ which produces excess drag causing the boat to heel over. Using lots of halyard tension helps to prevent this. It is vitally important that your jib halyard is marked so that you can easily re-produce fast settings. Care should be taken not to use wrinkles on the luff or a mark on the forestay as the guide to halyard tension. Instead, the trimmers should use the camber stripes in the sail as the main point of reference. Note that as a sail ages it will typically shrink in the luff and stretch in the leech which means that the camber in the sail will gradually creep aft. This in turn will mean that more halyard tension will be required to hold the draft forwards as the sail ages.

2.       Sheet Tension: the genoa sheet is perhaps the most important headsail control and must be played constantly, easing to accelerate, trimming to point. Sheet tension will change with every change in wind speed, but the basic premise is to trim as hard as possible without slowing the boat down. Remember speed first, then point. Adjustments are not as frequent in steadier breeze, but the sheet still needs to be adjusted for changes in wave patterns or to duck other boats. Sails can be sheeted harder in flat water than they can be in lumpy seas for the same windspeed. If you are fast sheet harder, if you are slow, try easing it slightly. In light airs the genoa trimmer should be sat to leeward, and should be constantly monitoring the shape of the genoa relative to the speed of the boat. Use the spreaders and shroud base as reference points so that known fast settings can be reproduced. Again, as the windspeed increases, so will sheet tension. On boats with overlapping sails do not be afraid to have the foot of the genoa touching the shroud base, but the leech should not ever touch the spreader tips.

3.   Lead position: The base setting for the jib lead should apply roughly equal tension to the foot and the leech of the jib, i.e. an imaginary extension of the sheet through the sail would roughly bisect the luff. The standard method for determining the median sheet lead position is to luff up slowly and watch the luff of the sail. It should luff at about the same time from top to bottom. In the real world the top will break slightly ahead of the bottom. If the top breaks too early, and the bottom of the sail is strapped to the shrouds, then the lead needs to be moved forward. If the foot of the sail is very round and well off the shrouds, while the top is in close to the spreader, the lead should be moved aft.

Base lead position applies roughly equal tension to leech and foot

The lead should be moved aft as the sail is sheeted in harder and operates closer to the top of its range. In light conditions, as the sheet is eased, the lead will need to move forward. A useful rule of thumb is that if you are needing to drop the traveller to keep the boat on its feet, then move the lead aft. Similarly, if the genoa is trimmed in normally, the main has been flattened, and there is still excessive backwinding, move the lead aft. Basically, as you become over powered, move the lead aft, and do not worry if the top tell tales don’t fly properly as you open the leech up. If your jib is trimmed so that the whole sail is working, but the mainsail is flogging to keep the boat on its feet, ease the jib. Give away the top of the sail to balance the boat allowing both sails to do some luffing.

4.     Forestay Tension: In light conditions you will need more forestay sag to make the genoa fuller and this is achieved through easing the forestay and/or lowers as detailed above. Similarly, in heavy conditions the rig is tightened helping to prevent forestay sag. This de-powers the jib and helps pointing.

Tightening the forestay flattens and depowers the sail

Upwind Trim: The Mainsail

Mainsail trim has two primary goals. First, balancing speed versus pointing by controlling the twist or how open the leech of the mainsail is. Second, keeping the right amount of overall power, helping to maintain a constant angle of heel and the right amount of weather helm. This section will address adjustments to mainsheet, traveller, outhaul, halyard, cunningham, vang and backstay.

1.        Mainsheet: like the jib sheet, there is no one magic setting for the mainsheet. It should be adjusted continually with each change in wind speed and/or wave pattern. Basically, increasing mainsheet tension reduces twist and tightens the leech, which makes the boat point, but also slows it down. Easing the sheet induces twist, which accelerates air flow across the sail. This allows the boat to bear away and accelerate. Initially, the main should be sheeted until the aft section of the top batten is parallel to the boom. Check this by looking up the sail from underneath the boom (see picture below). This is the ‘default’ or base position and at this point the top tell tale will be on the verge of stalling but should be flying about half of the time. Once the boat is upto speed, increase sheet tension until the boat starts slowing. Remember, speed first then pointing. The art is to find the delicate balance between speed and pointing, always trying to trim as hard as possible without giving away too much speed.

Base position with aft end of top batten parallel with boom

In light air, the sail will be eased and twisted from the base position. In moderate air the sail will be sheeted hard with the top batten at least parallel. In heavy air the sail should be sheeted as hard as the angle of heel will allow. Bear in mind that in choppy seas, more twist is required to keep the boat moving, and on flat water you need harder leeches for pointing.

Above: flatter sail with more twist. Note the top batten
is falling to leeward below the line of the boom. 

More leech tension creates a more powerful sail with the top
batten being pulled above the line of the boom. Be careful
not to stall the sail in this situation

2.      Traveller: the traveller serves two functions. Firstly, it controls the booms position relative to the centreline of the boat, and secondly it helps to steer the boat by controlling the helm and angle of heel in the puffs and lulls. To position the boom, set the twist with the mainsheet and use the traveller to put the boom on the centreline for maximum power and pointing. In light air the mainsheet will be eased to promote acceleration and keep the leech open and the traveller will be well to windward to keep the boom close to the centreline without too much downward pull from the mainsheet. In moderate conditions small adjustments will be necessary to control helm balance. It is important to dump the traveller quickly when a gust hits and you begin to get over powered, but equally important to pull it back on again as soon as the heel is controlled or the gust has passed. Wait too long and you have missed the opportunity to point once the boat has accelerated. As the wind speed increases the average position of the traveller will be slightly further down the track. In over about 18 knots of breeze you may need to ease a little mainsheet as well. However, before you ease mainsheet in windy conditions you may want to have the vang pulled on hard in order to prevent giving the whole leech away. Think of the traveller as the ‘tip meter’ once the mainsheet has been set for twist. The traveller position should be monitored continually and may need to be adjusted with every change in heel or any time the mainsheet is adjusted. 

The big question is whether to dump the traveller or mainsheet in the gusts. Well both will work. The first school of thought says that easing the traveller down the track in the gusts means that all leech tension is maintained and therefore the boat will continue to point. The second school of thought is that easing the traveller closes the slot between main and genoa which can slow the boat down and that therefore the mainsheet should be eased slightly in the gusts which will enable the top of the sail to twist off thus depowering the it (and keeping the boat on its feet) but because the traveller is still well up the slot remains open and the tension in the lower leech will keep the boat pointing anyway.The trick is to work ouit what works best for you and your boat. If you end up in a situation where the whole sail is ragging wildly then something is wrong; there is no reason why the sail should be flogging with correct trim and set-up! For more subtle changes in wind speed it may be better to use the traveller to fine tune the helm. In the big gusts dumping the mainsheet will get the boat back on its feet more quickly but be sure to get it back on as soon as possible.

3.       Vang: the vang is primarily an offwind control. It takes over the job of pulling down and providing leech tension when the boom is eased out and the mainsheet no longer controls twist. However, upwind in heavy air the vang should be used to help out the mainsheet with the job of pulling down the boom and maintaining leech tension. If the vang is hard on, the mainsheet can be eased in big gusts without giving up the leech too much. In light air make sure the vang is off using only enough tension to stop the boom from bouncing. In heavy air it may be necessary to ease the vang at the weather mark to assist with bearing away. Easing the mainsheet may not be enough.

4.       Luff tension (halyard and cunningham): halyard and cunningham both tension the luff. Initial luff tension should be just enough to smooth out the wrinkles in the front of the sail. Leave a few wrinkles in the bottom third of the sail in light to moderate air. As the breeze increases more luff tension is required to prevent the draft in the sail from moving aft. Use the halyard first, and when the sail is at the black band use the cunningham. Do not under estimate the usefulness of the cunningham, it is one of the primary sail controls that many people choose to ignore. As soon as the boat is overpowered start pulling the cunningham on hard upwind. It is easier to adjust and fine tune the cunningham when sailing than the halyard. As with the headsails, as the sail ages the camber will creep aft so more luff tension will be required to keep the draft in the correct place. Use the camber stripes as a guide.

5.       Outhaul: the outhaul controls the depth in the lower third of the mainsail. If you need more helm and feel, ease the outhaul. Power in the bottom of the main will increase weather helm. In very light airs (less than 5 knots) the outhaul needs to be pulled out fairly hard in order to prevent flow separation in the mainsail. If the sail is too full in light airs it will stall. In 5-12 knots the outhaul can be eased slightly to increase power. Once the boat is fully powered with all the crew hiking (normally about 10-12 knots of wind) the outhaul should be maxed out. The outhaul should not be eased much when running, the object is maximum projected area, just ease enough to remove any crease across the foot from excessive tension. The outhaul should be eased however when reaching (unless you are over powered). Make sure that you have the outhaul calibrated so that you can repeat known fast settings (make sure all sail controls are calibrated for the same reason!)

6.       Backstay: backstay tension does two things. Firstly, as the mast bends the upper two thirds of the mainsail flattens out and the leech opens up, thus de-powering the sail. Secondly, the headstay gets tighter (providing you have set up the pre-bend correctly to prevent over-bending), which prevents headstay sag, which in turn prevents the jib from getting too full as the breeze increases.

Broadly speaking as the breeze increases you will need more and more backstay. However, even in very light airs you may need to use a little backstay in order to help the mainsail leech to stay open. Since adjusting the backstay has a large and immediate effect on mainsail leech tension, main sheet tension needs to be adjusted at the same time. Bending the mast opens the leech, so you will need to add mainsheet as you add backstay, and ease mainsheet as you let the backstay off. You will also need to adjust the traveller accordingly.

Downwind Trim

The key to running effectively is to project as much area to windward as possible away from the mainsail, thus facilitating sailing deep. Do not get pre-occupied with having the clews at the same height as depicted by most sailing guides. You should start by altering the pole height so that the luff of the sail isn’t breaking too high or too low. You should then set the leech accordingly by using the tweaker lines. Pulling the tweakers on will stabilise the spinnaker when it is windy but don’t overdo it or the sail will stall. Use the centre seam as a guide to trim, which should be approximately perpendicular to the horizon. If it feels right it probably is right. The main thing when sailing downwind is to make sure the spinnaker is pressured up all the time. The trimmer and helmsman should be talking to each other continually so that the helmsman can get the boat really low when he has pressure and he doesn’t sail too high when he needs more pressure. Twisting the mainsail will also help you get deep, but at the same time it will make the boat more unstable and less forgiving. Be prepared to adjust the vang continually downwind and sail where you are comfortable. Sailing downwind is at least as tactical as sailing upwind with huge gains to be made by sailing at the right angles on the right shifts. If you tack on shifts going upwind you should gybe on them going downwind.

The crew should be well forward in light air, gradually moving aft and to weather as the breeze builds. The boat should ideally be heeled slightly to weather when going downwind which helps to project the spinnaker and helps the boat to drive off in the puffs. Weight should be shifted to stabilise the boat and promote surfing in heavy air. When it is breezy all the crew should be well aft, with one person being allocated as ‘vang man’ to de-power and power up the main as necessary.

Miscellaneous Tips

1.       Crew weight upwind: sail with a constant angle of heel, and with as little weather helm as you can stand. Generally this will mean sailing as flat as possible. In light air the weight should be to leeward and forward to induce feel and helm. In less than 5 knots of breeze it pays to put a couple of crew members down below particularly in sloppy conditions when it will help prevent pitching. Once the boat is powered up all the crew should be hiking hard and be bunched together around the maximum beam. Again keeping the crew weight together helps to reduce pitching.

2.       When the boat starts getting overpowered don’t fight the helm. Instead, ‘feather’ the boat slightly by sailing ‘inside’ the jib tell tales allowing the windward ones to lift slightly to keep the boat on its feet. Try to focus on steering to a consistent angle of heel. In other words don’t get pre-occupied with keeping the tell tales on either side of the sail streaming together.

3.       Don’t be afraid to pull control lines really hard! One of the most common mistakes that we see is things like the backstay not being pulled on anything like hard enough to depower the main or the mainsheet not being pulled on hard enough to get the boat to point!

4.       Remove all unnecessary items of kit from the boat. Encourage the crew to bring only what they are going to wear. You don’t need to have a pair of boots and a pair of shoes on the boat for example. Stow any spare kit, fenders etc over the keel.

5.       Make sure the bottom is clean and smooth. If the boat is anti-fouled, this should be rubbed flat with increasingly fine wet and dry paper. Do not under estimate how detrimental even a little bit of slime or weed can be to boatspeed. Being conservative we might say that having a dirty bottom will slow you down by 0.2 of a knot. This doesn’t sound much but it equates to 400 yards an hour. In a two hour race this is nearly half a mile!

6.       Make sure that all sail controls are visibly calibrated so that you can repeat known fast settings. This includes halyards and sheets.

7.       Similarly, put marks on the spinnaker pole controls so that you can pre-set it accurately before hoisting.

8.       Put a cover over the jib halyard at the point where it goes through the jammer. Maintaining halyard tension is vital when it is windy and most halyards will gradually slip as you progress upwind. Alternatively, keep the genoa halyard on the winch until you approach the windward mark.

9.       Keep an open mind and do not be afraid to experiment. Perhaps the most important point to recognise is when you are slow, and then to do something about it!

10.    Have fun!