Hardening Up for The Next Season

I have a slightly different approach to teaching sailing than the RYA, which I have based on observations of many sailors from absolute beginners to some seasoned podium amateurs. Also not forgetting the often outright bad behaviour of the "racing rabble" at starts and leeward marks. 

My approach comprises of starting, stopping, hardening up and bearing away. Tacks and gybes become a natural extension of good application of the latter two. 

Tonight I wanted to revisit "hardening Up",  aka "luffing" up.  We have then a few situations on outset of wanting to harden up, from run to reach or up to close-hauled.

1) getting a more or less stationary boat up to sailing close hauled

2) hardening up from a reach to close hauled

3) rounding a leeward mark - run to beat often

4) getting back to close hauled after tack

But first, some physics......in plain English

When we consider an effective luff (short for hardening-up towards the wind) to close hauled, we must think as much on what is happening under the water, as about the sails above. Blood is a little thicker than water, but water is a lot thicker than air, and many sailors seem to think boats only have wings in the air, while they consider the keel a useful static leeboard effect, or don't think about the aerofoil dynamics which are so much more obvious in the sails. Here then down in the more viscous stuff, we have the two foils for most all boats in the world, and they vary by depth, chord legnth fore-aft, and girth/bredth.


In the same way aircraft stall, or sails luff and collapse, foils have a minimum 'flying' speed below which they do not generate lift because the flow is not attached. They also in the same way as wings on planes, have an optimal angle of attack for that flying speed. Any larger angle  will create a stall moment and detach flow.

Luckily the designer has sweated and ground his brain cogs to balance the trim and angle of attack of the boat such that when the boat is properly canvassed for the wind speed, and the sails are set for close hauled, the boat will sit nicely with the tell tales flying or just breaking when the keel is at optimal lift-angle. This video is worth getting passed the Sausolito new beginners school to the NASA fluid dynamics research lab to help understand how the forces act, and how the combined forces from the sails and keel as 'fluid foils' resolve to forward motion on the beat and reach.

So we stall the keel of a boat by going too slowly or trying to force the boat to manoevre quicker than the keel flow can adjust. Instead of falling out of the sky, if the sails are still creating power yet the keel is stalled, then we make a good deal sideways movement called leeway, and this is not always so very conspicuous to the helm and crew on board. Usually we don't stall by too high an angle of attack, but when on the beat in a boat with a short cord keel, we can pinch the boat too high such that the keel is at too high an angle of attack to the direction the boat is being forced to sail by the rudder and sails. 

Flying Speed

The first thing we need to do in order for a boat to sail effectively on a beat or reach, is to get the flow over both foils to a speed where the foils 'fly'. This is far lower than the hull speed factor, which dictates optimal and indeed maximum speed in displacement mode. However if we don't achieve a boat speed which gets the foils flying, then we will not have lift as a resistance to leeway, and the forces on the sails will resolve to drive the keel sideways through the water. We also need to get the speed going such that the rudder not only 'flies' and generates lift, but the flow remains attached when the helm is applied ie a greater angle of attack to the direction of travel is chosen to steer the boat.

Here we come to chord length and maximum width. The longer the chord legnth from mid front to mid trailing edge, and the thicker the girth relatuve to that, the higher the speed before it will fly. I have never seen a boat with a 'longer' chord rudder than keel. The rudder will always then fly earlier than the keel and continue to fly at higher speeds at a steeper angle up nearer to its stalling point, allowing for it to steer the boat. There maybe could be a fanatstic boat with an aft keel to the same dimensions as the mid keel which then generates a lot of lift, but is of course useless for steering because it stalls when angled to the direction of travel.

Another point here you learn in dinghies and super light sports boats is that the keel foil itself generates lift, which creates a rotational force around the centre line of the boat. A powerful lift in a gust will heel the boat together with the action sails MORE towards a capsize. A lot of keel boaters think that the keel is like an underwater fixed paddle or board with weight on the end, which stops sideways movement like a barrier, and acts to balance the boat upright. This is not true as soon as the keel starts to 'fly', it is then generating lift and a heeling force itself. It is the ballast weight which counteracts this in keel boats. This is why some unwary keel boaters and slower dinghy sailors label faster boats "very tippy". As a short cord length keel 'bites' as it reach flying speed, in gusty weather it can help roll the boat into a capsize.

A feature of many older designs was that when beating in the 'design wind' or around there, the rudder itself was being forced into a higher angle of attack and creating actually more lift, a bit like flaps being applied on an aircraft. Hence the boat is tuned by the designer to have natural weather helm. This also creates more drag and risks the rudder stalling out, but the amount of lifting force can be quite substantial. Racing designs moved away from this because thinner and shorter cord foils and lighter displacement boats, coupled to some advances in hull shape, are more easily driven through the water, and less drag equates to more speed. On short chord keel boats like the Farr 30 or the Melges 24, the rudder is best kept neutral because if we had weather helm upwind, the keel would be forced into a higher angle of attack in gusts and the flow would detach leading to a stall. Just as the flow attaches quicker to a short chord and thin foil, it also detaches, and the angle of attack is more critical, there is no breathing room. The same is true of sails, if we set up and trim a genoa to its optimal depth mathematically, we get a very fine entry, not much 'knuckle' in the leading edge, and this is a very difficult sail to steer with. The knuckle in an average cruiser-racer sail allows the sail to fly through a far higher range of angles of attack to the wind, so we can steer through waves without needing to trim the genoa. With the short chord keels of modern racers, we have in effect a far narrower groove, but one which is easier to feel we are getting wrong at least. 

Sailing boats are luckily very much about the 'forces resolving' so although we have heeling forces, we have righting resistance and a hugh degree of forward drive element from sails and keels when they are all 'flying' in harmony in the beat. Aka "the groove".  Higher than being in the groove, the boat slows ;lower the boat can also slow or heel more. Once we get the foils flying and the sails in first trim, we can build nspeed and then sheet in and steer maybe even a little higher to obtain optimal VMG and hence progress to our upwind goal.

1. From Being Stationary

Taking this first and foremost after we have used layman speak for physics such that we understand all is not so easy in reality to get the boat into the 'groove'. We understand flying speed and that this must be achieved for a foil to operate. We understand the difference between the most often shorter chord rudder and the longer keel.  We presume we are lying at an angle to the wind somewhere between beam-to the wind and just low of close hauled.

Very few keel boats can sit at a close hauled angle and just sheet in and go. Some sailing dinghies can do this, but even then it is often not optimal. In racing the most common use for getting moving and onto close hauled is of course the start. We can have a really nice stacked up fleet who are all a bit too early and the whole start pauses and then becomes a slow motion kind of tesilated parade off the line. It seems everyone is struggeling to get power in, and everyone is stuck in their lane , pinned in by the crowd. Other times you see an all for early fleet stall up, and then suddenly on boat can peel off at the left end of a raft, finding some space to bear away into and then building speed before rounding up to the line for the bang.

The majority of keel boats need to get their foils up to flying speed before you can harden up onto the beat. It is egg and chicken. Speed before pointing. How much speed? Remember the rudder flies sooner than the longer chord keel in the majority of boats. So feel and steerage on the rudder is not enough. In say 6 knts of breeze, the boat will accerlerate and heel, and then hold course. In lighter airs this will be more subtle and in a larger keel boat you may want to refer to your inatrrumwents to see when you are at 'flying speed'.

This speed can be calculated using equations or estimated through expeirenxe and an eye and a feel for the boat is tracking. If yoy dont have a log, then you can experimwent in flat water and watch the quarter wave develop and stabilise as you accelerate . if you try and harden up and the wave bexcomes disturbed or moves to forward along the hull at its'  exit point, then you have not acheived 'keel speed'. The disruption to the quarter wave and that it move forward are a sign that more leeway is being made as the boat skids sideways, and boat speed is falling too much as you hardened up. If you look backwards off the stern you will see your wake is disturbed and the boat is tracking poorly, at this point maybe tracking sideways of the wake if you have dropped speed.

Getting back to our rudder-keel combination and that the rudder will fly both at a lower speed and at a higher angle of attack to the forces of forward motion generated by the sails and the hull. Thus you can get a good feel of pressure on the rudder which will get stronger as you push the helm down to luff up, yet the keel has not attained speed for attached flow, and is basically just a block of pressure against forward motion and the lee motion generated by the sails. The keel can even experience a circular flow generated by this side pressure which is contrary to getting the correct aerofoil effect. Because boats being sailed with 'white sails' go fastest on a reach, we need to ensure the boat is pointing quite low in order to get acceleration on when the wind is light or very variable. Here the steerage on the rudder helps us point the bow down, or if we can just hold course, it helps the boat track in more in a straight line as we wait for the keel to also 'bite'.

If we do the opposite and try to harden up too soon, then the keel is not working and eventually the rudder will stall. It can be interesting to look at a start line in quite light airs, around 3 - 5 knts wind, to see how the forces resolve on different boats which are being sailed slowly towards their final prestart position, and then actually starting, from a vantage point in a stationary boat. Look at the direction the bows are pointing versus the actually tracking of the boat, the abruptness some are being hardened up with, and the wake in the water they are making, which is often not just from the stern, but from the windward side as they slide sideways before the keel bites. This is also an established advanced positioning technique and in dinghies has its' extreme where the dagger board is lifted to allow the boat to slide. In keel boats, it is counter productive in most situations.

2. From Reach to Beat

Here we are looking at the situation when you have good speed on a reach and so then how to achieve a smooth and most efficient transition. Typical racing conditions are when you come fast into a start line on a reach and swing up to start immediately or in cruising it is when you round a headland and assume a higher course.

Speed is your friend here, but haste and pressure is your enemy.

In moderate to heavy breeze, say anywhere from 14 to 30, then you want to ease the boat up assertively without stalling the rudder by too high an angle of attack, and without over powering the boat and overwhelming the crew as they try to sheet in and get onto the windward side of the boat.

The first point here is that to acheive that transition, you require to get the sails ready for the beat before you leave the reach, otherwise they will be too full and powerful when you come on the beat. If we need to take a reef in for the beat, we should plan well in advance and try to ease the main out and drop down in a lull, or luff abruptly hard up head to wind and stop to do it, before reassuming a reach and then hardening up. For just some flatterning of sails, Here you should think outhaul, kicker, backstay and traveller position. It can be a good idea to 'index' the traveller to a a third of the way up from the lee side, and to have marks on the backstay for beating which you haul in to before you harden up. With reefs, flat sails and back stay, it is always easier to slip out if the wind proves to be lighter than the settings chosen, while it is alwasy harder to put these on if there is more wind pressure that you reckoned with. This is especially the case with a reef.

Secondly when it is blowing around or above 'design wind' (when the boat is fully powered up) then you want to coordinate the trimming of sails such that you steer first, releasing a little pressure, and allowing the crew to pull in. In cruising we can be a little leisurely and take it in a series of steps, while in racing we want to really have the crew trimming just behind the helm swing, such the sails come in quickly through the curve the boat is steered  round. On boats with big genoas it is often the mainsail which is set to the beat, and can be indexed on not only the traveller but also by the boom angle to the centre line and the amount of mainsheet taken in. Many helms on both cruisers and racers wait for a slow crew to trim the genoa hard on before asserting if they are sailing correctly on a beat from the tell-tales on the genoa luff. You are far better served by steering to the 'indexed' main set up until the top tell tale breaks and the second down starts to break then moving up to a point where both fly all the time, when you have a bit of a slow to trim set up or crew are a little 'tired' such that you are in fact pinching just a bit (sailing a little high of optimal close hauled). The main is then given a final trim once the proper course is attained and then as the speed builds a little, both sails may need a final trim.

Moving then quickly on these last two points to discuss light wind technique for reach to beat., we can use the same end techniques of using the main tell tales, but here we want to avoid them breaking as we harden up and have the top one breaking less than 50% of the time when we are setting close hauled. This helps because there is more air flow over these coming up on the wind than there are on the genoas, which are being disturbed by the deeper movements and the disrupted upwash as the boat turns  the bow through a greater arc than the center point, up towards the wind.

Trimming on the sails should be progressive with the aim of trying to get the leech curves to match, but for the reasons in the last paragraph, the genoa or jib take slightly longer to settel with perfectly attached flow due to the longer arc they turn up through than the top of the main.

In steering, especially in very light winds, we use the mainsail slightly ahead of the jib to induce rotation up towards the new close hauled course, and we can usually heel the boat to leeward a little more than the pressure does with our crew weight such that the hull also steers the boat, with the helm just following on and adding some subtle persuasion. The rudder will stall quicker of course but also use of the rudder whcih is out of balance with the power in the sails, will as we understand now, stall the keel easily. Using the pressure of the mainsail we seem to be able to have a more harmonic luff. This effect can be difficult to feel on a larger keel boat, but it is indeed there. It is of course most noticeable  in racing dinghies and sports boats in the sub 26 foot range.

In light airs we do risk always stalling the keel or stalling the boat when coming up from a reach, because we either brake down as we move from the faster point of sail, or we hold way and the boat generates its own upwash which can lead us to point to high or too low and eventually stall. Very often though we experience more relative wind in very light airs, when hardening up from the reach and these two events, keel stalling and sailing in a false, self generated upwash wind, are transient.  A good many boats in very light airs will accelerate up onto the beat due to their being more apparent wind and thus more pressure on the sails and keel as aerofoils. When reaching we may find ourselves having to sheet in as we sail into a 'hole' or to steer up to keep enough pressure in the sails for them to work as aerofoils.

 

3. Rounding up to Close Hauled from a Run (leeward mark)

This is of course an everyday theme for racing sailors, while cruisers tend to be a little more often the gentle side of going run to reach rather than all the tea spilling trauma of hardening the bow up by 120' or more.

It is an area which many racing sailors get wrong.  Only back in August I saw a professional former olympic sailor throwing a good third place away in a 12mR race in spectalar fashion, sailing a good quarter nautical mile on too low a course for the beat. The main reason racing sailors get it badly wrong is usually either spinnakers or other boats getting in the way. However there are some more subtle elements which make the difference between a mediocre rounding and a good one.

Firstly back to preparation. The crew need to be alerted in good time, and start the small and major jobs, plus think ahead to where they will be once the mark is abeam and the nose is going up to the  beat. The jib should be up and tensiined for the preaumed beat conditioins as far as fifteen boat lenghts out, and thus done beforee the drop. In a planung maxchen the combinarionof the drop and crw weight being forwaéd agai, will usu({ 5kckit off thé planeFor the average crew in any wind and even the top crew in heavy wind, it pays to get the spinnaker down with some breathing space - time to round in a seamanlike way ( or what the new r.18 calls it). The textbook rounding is to go in wide and then tighten up hard once you have the bouy on the beam. The reverse of the bear away at the windward mark, which is tight onto the mark, easy out.

Speed at the leeward mark is to a large extent your enemy in accomplishing what is on average a turn through  135° ( 180 - 45 on compass bearings in a model race) . You may also really want to tack immediately, which makes the turn a full 225° if you pull it off in one fail sweep. Speed is your enemy then in three ways

1. Time to get the crew coordinated and in place for the rounding to close hauled evapourates rapidly !
2. You close in on boats ahead, who as we will see, may well be blocking your rounding and  'exit'.
3. Hydrodynamic issues in sailing's version of the 'hand-brake-turn'.

The first is easy to talk about in the cabin or slipway before you race, but you have to have the courage of your convictions to use the rules ( and the all important r.18 is changing as mentioned for 2017), in order to go in wide and harden up as the beam meets the bouy. Sailors get rightly worries about boats without rights barging in, but there is no point in being either stumh and not shouting at them 'no water' while on the other hand, closing the bean door and causing a collision. Offenders should be called and protested, and some humility here, th may be having a bad day or panic moment and not have anticipated your wide in manoevre or even seen you.

Two boats cannot round the mark at the same time on the single, perfect 'hockey stick' line, one would need to go round the outside, which is 'real dumb' because you end up  on a far lower track close hauled, and most likely in bad wind. A bigger or much fasster boat can get away with this over a lesser competitor who has rhe right line, and that maybr their best option. But in OD or a decently tight HC bracket, you need to just draw a queu ticket and take your positiin in line for the 'turnstyle' . this can mean then slowing more down, usually done by an early kite drop and perhaps cwentring the main such that the wind slides both sides of it, which is a cvery effective brake and works even with reefs in. Infact in the abscence of last minute starboard smarty pants coming in on your port side, the order of rounding can be decided quite far back, as loing as you keep your treansom aheadand maybe duck down to 'soak' to the mark rounding on a ddw run or evwen a littke by the lee.

The ideal point to be aiming for on this last little soak is not the mark, but an imagibary point around a boat length to stb ( on a port side rnding) and half a boat legnth upwind, where you take the boat through onto a reach to meet the mark itself close in on the beam,and then car on turning. Ideally the manoevre feels like one constant turn, but moat often it is run to reach- pause - reach to run.

There is a prudent reason for doing it just that way. On the dead run, the keelnhas no angle of attack and is just a symetrical foil sliding through the water with  no notable pressure pockets at sub 10 knt speeds at least. If you attempt a really sudden 'hand brake turn' by coming in tight and spinning on an axis right beside the mark, then your boat will create a lot of turbulance arouns the hull and keel, and despite the sails being truimmes in and drawing, you fail to make good progress. All experienced racers have done a good turn, wide in and so on, only to find a boat apparently stopped right in their way for close hauled. Often the okld flow from the run is shaken off by a bad turn, and then a circular tuebulance occurs aeouns the keel as it ia pushed aideways by theomemntum from the run, ddw angle of the tuening point, and vector that creates in abscence of the  keel creating lift. This is exacerbated un adverse tide where we either get a lifted situation or a headed situation.

So if we charge in on the mark and whip the boat round, we shake off the old flow on the keel, and it takes time for the new flow to eastablish and the aerofoil -angle of attack to generate lift. Reaching in from the imaginary pin towards the mark, solves this problem, if you can get upto keel speed. A but like a plane taking off on a runway, it needs speed before it can be put into a climb with a higher angle of attack to the oncoming air.

Now there is a fancy little tactic you can read about in some texts and in Y&Y articles, where you shoot the boat up into the wind after passing the mark, and then fall off onto what should be a track for the beat which is high if the natural  line - hnce you gain an upwind VMG advantage and you give worse bad air to the boat behind you. You really do need a lot of boat speed to pull this off, for the reasons discussed above, otherwiswe your keel won't fly and you may think you are tracki hugher, but actually making leeway big time. The same is true of wanting to tack straight away- you have to have enough speed to both come out in a track high of the mark bouy, and to fly your keel asap you are sheeted in. Once again uf you risk hitting the boat ahead in thwe transom, then you can either go low and long, or slip out the sails and try and defend your ranking by forcing other boats behind round your lee, and hence into a big area of wind shadow. The highewt risk tactic is toi try and roll over them because you have no rights and if they start to 'bite' and sail correctly, the are feee to luff you once clear of the mark. Tacking away may kill your speed enough in lighter winds that you deift onto the bouy due to the leeway you make because the foil is stalled.