Hi, if you have been to this page before, welcome back. I have added new gems to the bottom of the page. This area documents a series of common points that are a useful pointers on yacht rigs. It is by no means advice on how you should design your mast or how we would design your mast. But there are interesting things that often come up or are misunderstood, it helps to recognise them and look at the surrounding issues..
Geometry: Cap Shroud/ChainplateMost sloop rigs which use rod rigging use a cap shroud angle of 10 degrees to the mast wall. This is normally considered a state of the art angle and it usually permits a reasonable compromise between sail sheeting and rig stiffness. Similarly, the chainplate angle for an overlaping 140% genoa on an inline spreader rig is normally about 13.5 degrees from the forestay (forward end of J). This defines the most common chainplate position. With the V1 shroud vertical and the cap shroud coming from the hounds at 10 degrees it then remains to obtain a modest spreader envelope to generate even spreader pokes on each spreader; kind of like joining the dots. For 110% genoa and swept spreaders on the gunwhale a whole different approach is required. However, it rarely pays off to have a cap shroud angle greater than 14 degrees. If the cap shroud angle that is too large this can actually lead to some torsional instablity which has been seen on carbon rigs. Carbon rigs have a fairly low shear modulus and are prone to excessive twisting, which can be annoying or unsettling in some cases.
Sail Area/Displacement RatioA lot of designers (and journalists) put great store by the sail area to displacement ratio. Whilst that is their business, we think that they would be better off to consider a ratio of (mast height & sail area) to righting moment. As this is a better way of making a comparison. This ratio is a rough indication of sail power (overturning moment) to yacht stability (righting moment). The problem with the sail area displacement ratio is that it fails to take into account stability generated by beam or form, draft nor aspect ratio of sail plan (distance from CLR to CoE). Clearly a beamy yacht with low aspect sail plan can handle a lot more sail area for its displacement than a narrow yacht with a tall mast. So the alternative is Sail Area x Height to CoE / RMC. This ratio will soon start to give some feedback on whether the yacht can handle its sail plan and we think it is a better form of comparison when comparing two similar yachts. I was recently informed that the ratio I am discussing is an upside down dellenbaugh angle, which is fine with us.
Factors of SafetyFactors of Safety on rigging vary greatly from design office to design office and there must also be variance on the type of vessel itself. As commentary on our industry here are some good rules of thumb. Forestay 2.0/2.5. Verticals 2.25/2.75 and Cap Shroud 2.75/3.0. The D1’s vary between 2.75/3.5 and other D’s 2.5/3.5 One issue is that whilst many designers are using RM30 the righting moment at 30 degrees as a basis for maximum safe angle of heel and therefore maximum safe working loads, current practise varies widely on analysis under reefing and if reefed loads are not applied to the D’s individually, then it transpires that much heavier D’s are needed or that higher Factors of safety are required. There are a lot of yachts that do not reef at all (race yachts) but if they have a delivery mainsail of cut down dimensions then it is important that these sails do not overload the adjacent D. Otherwise a safe move can turn around and bite you. Worst of all some designers are keen to compare factors of safety but use RM20 or RM25 so the factors do not really get a fair comparison. Clearly some yachts would dip their gunwhales under and actually sink at 30 degrees of heel, so care is needed before setting factors of safety or the basis on which these factors might be applied.
Righting MomentNearly all rigs today are designed on the basis of their vessel’s righting moment and nearly all engineers designing rigs and the loadings on hull and sails want to know what that righting moment is. Most hydrostatic programs give this output and it is a common element of stablity important to the design of any yacht. FIND OUT what it is if you want a professsional rig design. HINT; the easiest way to find it out is to obtain from your local measurer (usually at minimal cost) the rating certificate (IMS) of a yacht the same class or similar design. However a number of naval architects will do the work for you, and locally we recommend the IMS measurer (Jim McElrea). The Professional Boatbuilder magazine (USA) recently did a great article on this subject of stability for all levels of reader.
Four Rig Styles (Sloop)Rigs (modern) generally come in four flavours. There are masthead and fractional rigs and there are swept spreader and inline spreader rigs. Combine these and you have four possible combinations, I would like to propose to you an interesting set of generalisations one can make about these four flavours.
Masthead Sail Plan with Inline Spreaders
Racer IMS / Cruising
Downwind Racing Isp=I (sleds)
No Runners (unlikely but possible)
Large yachts, Large Crew
Masthead Sail Plan with Swept Spreaders
Full on Cruising No runners (probable, quite possible) MPS or no Spinnaker Yankee, furled reacher Large yachts, small crew
Fractional Sail Plan with Inline Spreaders
Full on Racing PHRF, IMS Masthead Spinnaker 'ideal' Always have runners fully crewed racing small yachts, large crew
Fractional Sail Plan with Swept Spreaders
Racer / Cruiser Masthead Spinnaker for Racing Fractional Spinnaker/MPS for Cruising No runners (possible) short handed cruising, short handed racing small yachts, small crewThese comments about four basic configurations are obviously just rules of thumb, and at first it looks fairly confusing, but it works for us and whilst there are exceptions to these rules due to a wide or narrow chainplate width and genoa overlap considerations, these observations are things that you might find useful. Now, speaking about chainplate width in particular, not enough people seem to realise how important this is. For example if you have chainplates a 1m off centreline and you move them out to the gunwhale at say 1.5m from centreline that is a 50% increase. The loads in the side rigging will therefore drop by 33% and in a lot of cases, the savings in rigging weight and mast weight will be far greater than building your mast in carbon fibre!! The savings in cost of a light alloy mast and light side rigging is also something to be considered, you save money and you save weight. A carbon rig with chainplates on the gunwhale might be lighter again, but cost can be a factor. We have to say that self tacking headsails make a lot of sense for cruising or short handed sailing or to just plain keep costs down. This does not mean that you must have less sail area, though for a racing yacht the rules kind of mess this up (we know). The point is that you can not put on wide chainplates if you have an overlapping headsail because it ruins the sheeting angle. A properly designed sail plan with a self tacking jib can allow very close sheeting angles and no loss in power with the right size of sail plan. So, whilst nonoverlapping sail plans with wide chainplates are not suitable for everyone, the saving in cost and weight is worth considering in many yachts.
Spreader RakeSpreader rake is an interesting subject. If you have read the above and determined that you are interested in an inline rig; skip this. Once a swept rig is decided on the next question is what angle of spreader rake. If you have a spreader rake of 30 degrees on a fractionally rigged yacht, the chances are that you will need little or no runner loads. Indeed many yachts with 30 degree rake have no runners what-so-ever. The cap shrouds are effective at tensioning the forestay and provided J the jib foot is not too long considerable forestay tension is developed without runners. On a masthead rigged yacht the backstay is effective at tensioning the forestay and again without any runners you can tension the forestay using only 20 degrees of spreader rake. As you reduce rake to only 15 degrees the need for checkstays and runners starts to eventuate, sooner if you have an inner forestay/staysail of course. At spreader rakes of less that 10 degrees our best advice is DON’T. We say this because you obtain the worst of both worlds with spreader rakes between 5 and 10 degrees. You need runners and checks because if you gybe with 5 degrees spreader rake or fly a spinnaker you might snap the sidestays if you have no runners. At the same time you have a swept rig and can not modify mast bend / luff curve as in an inline rig. So, you have not been able to get the benefit of either configuration. The cliche ‘in for a penny, in for a pound’ holds true albeit poorly paraphrased. If spreader rake is between 0 and 5 degrees this is to all intents and purposes inline and would normally just be treated as 0 degrees/ inline.
IMS LoopholesAt time of writing this the IR2000 rule has been mooted and it remains to be seen what will become of IMS. However, an interesting aside is the issue of spreader length. Most IMS yachts are restricted in terms of genoa sheeting by the length of the top spreader. As stated above the rule of thumb is a cap shroud angle of ten degrees to mast wall. HOWEVER, for IMS yachts a few wrinkes are evident. Let us assume that you develop a cap shroud angle of only 8 or 9 degrees. The stiffness and rod strength requirement in your cap shroud shoots up very high (so does cost and weight) and similarly compression and inertia and weight in your carbon mast also get bigger. But for all this you are fairly or more than fairly compensated by the IMS rule you will in fact be given a nice bonus in this respect. The truth is that you will now be able to sheet your genoa much closer in the higher regions which are normally forced out quite wide. So, you might potentially make a big improvement in your sail trim, sail shape and in the driving force of the yacht. Well, that’s the theory.
The other wrinkle at time of writing is the oversize mast issue. Most IMS yachts have oversize masts, or at least fairly big masts. This is due to IMS compensations on mast windage. Mast windage is a tricky one. We know flagpoles develop drag. We know that rotating wing masts generate driving force. A plain old yacht is probably closer to a flag pole. So, the IMS rule gives a compensation which most think is fair or more than fair. As a result a number of masts have been made with core in the side walls so that large sections with very thin walls have been made. It is rumoured that IMS will be modified to clamp down on this and to herd designers/ builders to a more sensible size of mast generally speaking. Of course IOR pushed everyone towards a very small very heavy mast with a thick wall, this was equally silly and I won’t bother explaining that unless you are interested. At the end of the day it is unlikely that IMS will penalise large masts, probably just fair things up a bit. The large masts and surplus inertia issue does actually dovetail very nicely with the narrow cap shroud angle / short spreader length issue discussed above, so in effect each encourages the other.
IOR Masts were small and heavy. Requests have been made for me to discuss why I think this was so. The IOR rule gave no windage allowance for a large diameter mast, so clearly a small mast would have less windage. At the same time IOR yachts developed (became type-formed) with lots of internal ballast. This internal ballast raised the yacht’s CoG and reduced the righting moment. This was done on purpose because whilst designers found heavy yachts to be an advantage they were penalised for a high righting moment and so hence CoG (centre of gravity) was raised with internal ballast to compensate. “Why” I hear you ask. Well let’s face it a rating rule such as the IOR or the IMS is not about designing fast boats; what it is about is designing boats which are faster than the rating rules thinks that they are. So designing a slow boat with poor performance is GOOD if the rule thinks that the performance is worse than it actually is. So, anyway given the high CoG environment it is not impossible to have a heavy mast because there is still lots of internal ballast to play with. The small sections with heavy walls were able to bend a long way without breaking and as a result a degree of safety was built into the masts. That is to say the crew had the good sense to become frightened before it was too late. This inherent safety let a number of mast designers and mast builders play some really interesting games the extra safety allowed them to take some extra risks. I think it is fair to say that Bruce Thompson and John Green at Sparcraft UK had this figured out better than anybody. Since the yacht designers were still able to achieve their target weight, CoG and Righting Moment using a small low drag section made sense. Very narrow sections with five or six spreaders were shut out with the low rigging penalty so overall if you look back at mast extrusions designed about that time they were both heavier, smaller and thicker walled than the IMS extrusions most commonly on the market at the moment. Whether this is good or bad is hard to say; it is definitely disruptive and costly to owners that’s for sure. It took a while and a lot of investment in new extrusion dies before IMS mast sections came on-line. For this reason many early IMS yachts were rigged with IOR masts. Similarly when the rules are next changed it will take a little while and yet more money to create even more extrusion dies. This may prove to be the end of aluminium masts at Grand Prix level. If the IMS rules simply modify the 2:1 aspect ratio, then the carbon mast builders will have a big problem too. In regards the IMS windage compensation it remains to be seen if the compensation really is “too good” it might actually be perfectly fair. The state of computational fluid dynamics makes this a very hard problem to solve. The reality is that as long as everyone ‘thinks’ that the compensation is over generous, then they will continue to make oversize masts; some of which are dangerous in respect of thin wall buckling. The IMS rule may have to generate an unfair windage allowance merely to herd mast sizes back to a sensible size regardless of what is technically right or wrong. From our perspective when designing the mast for a non-rating fast cruiser we generally recommend masts which are lighter than IOR and heavier than IMS in trying to create a safe conservative mast. This keeps costs down while maintaining performance and therefore value.
Well 1999 saw the arrival and departure of Crazy Coyote the French IMS yacht with the unstayed wing mast. Whilst in the discussion of IMS loopholes this yacht seemed to take this line of thought to an extreme length. We should all feel sorry for the owner who has spent this money and the measurers who are put in a awkward position. Clearly the rules are not intended to deal with such a situation and this makes it a no win situation for everyone. In our view the idea is pretty extreme but we have no way of making judgement. There are some contradicting aerodynamic theories plus in a level rating scenario one would hope that the wind loss of all the rigging is less than the losses from a more flexible mast which will tend to lay off more. It is too early to tell and I suppose it would have been better if a less extreme example with light rigging had been used as a test case. It is not really possible to expect such radical change overnight.
Mast JacksMast Jacks are a total nightmare for a rig designer, the problem is that too few sailors have a degree in hydraulics (just kidding). There are a couple of things that should be borne in mind. Firstly if you have a load from your rig designer for jacking up the rig, then he should work out the pressure for you. If not this load must be converted into a pressure that you can read off the hydraulic gauge on the pump. In order to work out this pressure you need to divide the load by the area of the cylinder bore. As a result, pressures usually come in psi (pounds per square inch) or kPa (,000 Newton per square metre). On occasion the situation is confused by the use of Bar, one bar is another way of saying one atmosphere of pressure. Secondly, if you have two jacks, one on either end of the jacking bar, you better make sure that you divide the load by two times the area of a jack. This is where it gets messy, the same pressure on two cylinders gives twice the load. Not everyone believes this, but I assure you it is true;). Moving along to more complicated issues is the orientation of the jacking bar. Our office prefers to have the jacking bar run athwartships. This causes the least problem with mast rake and mast bend. We recommend a self-leveling top to the piston; these are also called ’tilt saddles’ in some quarters. If a mast has a lot of rake the jack pushes on one corner without a self-leveller; a colleague of mine on the Il Moro di Venezia team was hit in the face by a self-leveller which flew out from the jack/bar due to slippery oil. MAKE SURE THE SELF-LEVELLER IS PERMANENTLY ATTACHED TO THE JACK. We try to set up the jacks so that if the jack is pumped to full height it can only lift mast a maximum of 10mm above the wedges. Otherwise if you use (say) a 6″ jack with 4″ wedges you could set it up to so as to run the risk of causing real damage if somebody is not paying attention and they overjack the rig 2 inches by mistake. If the jacking bar runs fore/aft the load sharing between the two jacks will not be equal. ideally. The two jacks will supply equal force, so this develops bending moment in the mast, the bar has to be longer, sometimes making insertion difficult and finally affects of rake and bend are harder to deal with on a fore/aft bar. Lastly, they tell me that oil at only 2000 psi is injected into your blood stream if you are nearby a burst hydraulic hose. But at 10,000 psi it will blow a hole right through you. In your eye you will be blind, plus you have a good chance at death from the oil poisoning you. So, never treat hydraulic hoses badly, don’t stay near them longer than you need to. Just cause they rarely burst does not mean that they wont ever. Be especially wary of mast jacks because they usually operate at up to 10,000 psi which is a pressure far far higher than probably any other equipment on the boat. Make sure an expert checks your hoses and gear if it is all rusty and has not been used for a while. Here ends today’s lecture…..
Whoa, back up a bit. So, you want to know why jacks are used at all? Well on small yachts you have turnbuckles (rigging screws) and if you get a big spanner you can wail on this and get that rigging pretty tight. Then you can go sailing and tension up the leeward side until it is just the way you like it. Once you get to a 45 foot yacht that spanner got quite large. If you consider a 100 footer there is just NO WAY you can put on meaningful tension with a spanner. If you decide to just tension up the leeward side that will work you can tack about the place in increasing winds until it is all just so. Unfortunately time is money and the wind never does what you want. If you have a problem and you are at the dock it becomes a catch 22 when you need to sail to get the rig down but you can’t go sailing until you get the rig down and fix it. Regardless of the time issue, if you drop the mast of a 100 footer messing around tuning it you will look a right idiot. The cost of a hand pump and steel jacks is low and you can store them in such a way as they wont rust in the engine room or ashore. What may seem extravagant waste on a 30 footer is a total necessity on a 130 footer.
Survey & Plan Approval for RigsRig Design Approval was the subject of a recent question sent to our office. As far as we are aware there is only Germanischer Lloyds offering a rig design approval service. Basically, they offer a service of approving each drawing of the rig design and they can further offer to be present during construction as well. Some insurance companies are refusing rig insurance unless the rig obtains G.L. plan approval, which adds another dimension. Most notably this applies to large Super Yacht rigs made with Carbon Fibre. Further, we think that the cost of the plan approval might actually add re-sale value to the vessel. We imagine that if you are about to purchase a $10M yacht that you are likely to look favourably on a G.L. approved rig because nobody wants one of those to fall down or be replaced. The cost of the approval appearing to be ‘peanuts’ by comparison. It is fair to say that many racing yacht RIG designs with ALUMINIUM mast tubes would not obtain such an approval, but G.L. make no apologies for this and for the right type of vessel we expect that G.L. approval is a very sensible move. So, like most things it is not appropriate in every instance but it is very useful in the right circumstance. As a footnote we should add that Germanischer Lloyds is not a German branch of the English Lloyds; it is an entirely different (separate) organisation. Further, neither of the ‘Lloyds’ are connected with the insurance market/Names.
SpreadersSpreaders. The number of spreaders on a rig is normally something that can NOT be adjusted and most people don’t really know why they have a particular number of spreaders and/or why the boat next door has more or less. Certainly, there is confusion over just how big the weight savings are if you got yourself some more… There are several overlapping issues. Generally speaking it is lighter to have more spreaders. Take a rig with one spreader, if you add a second spreader the length of mast between supports is reduced substantially, this has results in a drop in the required mast inertia but only transversely, this means that a lighter mast can be used. Fore/aft there was no benefit. As a result while a lot of single spreader rigs are based on round tube as you move towards 4 spreader rigs the mast shape becomes increasingly elliptical. What this means is that because the mast inertia are lower transversely a narrower section can be used, but it still needs the same fore/aft inertia. The weight saved from the lighter section more than cancels the weight of the extra spreader and the rigging wire weight hardly changed at all. Once you get to three spreaders, the weight increment saved with more spreaders becomes much less and by the time you get to five spreaders you may well be going backwards but it depends on the case and the mast sections available. The IMS rule has hung (clung) on to the low rigging penalty (LRP) which means that the rigging and/or first spreader can not be below 25% of I. This effectively blocks rigs with checkstays from the gooseneck (Tim Stearn) or 5 and 6 srpeader rigs where you would naturally put the first spreader quite low down. So, despite the fact that it makes little sense there is also a rule block in play. As if that was not enough there is a 2:1 aspect ratio limit under IMS; well it is not a hard limit like the LRP, but it effectively makes it pointless to create a mast with a lot spreaders because it’s not worthwhile from a windage point of view. Moving aside from the rules, there is a basic conflitct between complexity and weight saving. In this case a lighter mast should actually be cheaper, but the extra spreaders create extra labour hours so, for most yachts the optimum is around 3 spreaders, 2 for a small yacht and 4 for a very large one. There are all kinds of proviso’s and exceptions that go with that so don’t take this too far. The interesting bit is that transverse inertia for a typical sloop are based on panel length squared, compression etc etc. So, if you have no spreaders and you decide to put in one it will halve the panel length, this quarters you mast inertia. So, in theory if the spreader is properly designed and stayed, required mast inertia drops by 75%. This is pretty substantial I would say. Then if you put in another spreader (two) the improvement 66%. Three spreaders 44%, Four spreaders 36%. Of course the mast inertia fore/aft didn’t really change so you didn’t save any weight there. If you took that one spreader 75% case, if you remove 75% of the side wall then it is probably much too thin. So you go to a narrower mast with a thicker wall, this mast is of course heavier than the big one with the really thin wall. So, after going around in circles you wind up with modest overall weight savings despite increasing levels of complexity in design and construction. You didn’t find that in the least bit interesting(?), well you’re probably right, but its my job (life’s work) and I find it really challenging and fun to investigate all the options because there are so many overlapping issues when you consider diamonds, masthead spinnakers, IMS rule big mast issues discussed previously, runnerless rigs with highly loaded backstays and so on.
Neutral AxisThe neutral axis of a section is it geometric centre of area. If plane sections remain plane and a bunch of other engineering stuff, then when you bend a section along its principal axes then there is no strain on the neutral axis that is to say it is between the region of compression on one side and the region of tension on the other side. For mast sections it is commonly confused with the centreline. If a mast was a perfect circle or ellipse the neutral axis would be the centreline too. However for most mast sections they represent an egg which has been booted up the backside or if you prefer an inflated bullet. In any case the net result is that the neutral axis is some 55% to 60% aft along the section. The question arises, should the spreader rake and chainplates be set from the neutral axis or the centreline? There actually isn’t much difference. You could argue that by putting chainplates and stays on the centreline it will induce mast inversion because you are compressing the mast on the forward face. However, the mast will probably still bend the same way and the so-called inversion will actually stiffen the mast up. Further some people get really lost because with stiffening in the mast the neutral axis can move in every mast panel. So at the end of the day use the mast centreline is our advice. Thus V1 chainplate for an inline rig is halfway between front face and aft face of the mast when you layout the deck plan.
BoomsWe have been asked to discuss booms a little so I will try to start at the beginning. I will try and break it up into small blocks so I can write a bit at a time.There are quite high bending moments created in a boom when the boom vang is tensioned sailing off the wind. Compression is usually quite low aft of the vang and flexure is the main issue. The boom is normally designed to be stronger than the maximum pressure setting of a hydraulic vang (larger boats). In turn, the specification of the vang size is related to sail area and righting moment, as well as the geometry of the vang and boom. Now as well as bending from the vang sometimes there is bending from the mainsheet if it is not near the clew. Eventually at some point the sail is reefed and the clew moves forwards, this may be nearer the mainsheet or further away from the mainsheet. Typically the load the mainsheet exerts on to the clew of the sail is three times that of the vang. So, even if the mainsheet is three times closer it can still become quite significant whilst reefed.
A separate issue is why booms break. There are various reasons why booms break, generally speaking it usually arises due to stress concentrations or other niggles which develop into cracks which lead to a failure after a relatively short period of time; even though the boom was plenty strong enough on delivery. We have identified a few of the secondary issues that sometimes fester to become critical, we try our best to avoid those. However in defence of many boom builders, when a yacht is sailed badly either on purpose or accidentally, it is relatively easy to break a lightweight racing boom. Just a question of technique, or in some cases staying awake. From our America’s Cup experience dating back to 12metre yachts we can say that regardless what class you are sailing most booms are broken at lunch time. What happens is that everyone rushes for the lunch chillybin and the boom tends to slap around with the yacht kind of hove to. This is fine but given a bounce the boom can sometimes flick up and snap like a carrot when the vang bangs tight. Alloy or Carbon makes no difference. Second kind of problem shows up in countless Whitbread Race booms where they break immediately aft of the vang. We think it probably has something to do with the large hole that used to be cut on centreline to accept the boom vang lug. The stress concentrations around that hole make it a bad place to put a hole and while in theory you can compensate for it in many cases that compensation was not adequate since the boom broke.
Above photo shows the Wallygator Winged boom. This is a composite boom that has wings to make it wider on top and therefore tidier for sail flaking. Lazy jacks are attached to edges of wings.
Self-Tacking JibsAfter the reading this rig hints page, Angus McKenzie from Melbourne Australia wrote to us asking for information on exactly how self-tacking jib systems work. The following is a broad description which we came up with to answer such questions as why the track is normally curved and how you might work out the correct amount of curve.
Self-tacking jibs offer a simple system of headsail sheeting (trimming) for short-handed sailing and for simplicity. The headsail is made with a 92% to 85% LP measurement so that the foot of the sail finishes in front of the mast and can tack from one side of the yacht to the other without hitting the mast and getting snagged on it. Sheeting is transverse and so fore/aft control or so-called lead angle is usually manipulated by having a clew board with a series of holes so that lead angle can be manually adjusted up and down by moving a shackle. Once fixed these are rarely moved.
The sheeting of the sail normally takes one of three forms. Here I will limit myself to systems where there is a transverse track across the vessel and where there is a single car riding on that track.
1. The sheet is dead ended at one end of the track, goes to the car, goes up to a block on the sail, goes back to the car and then goes to the other end of the track, around a sheave and off to a cylinder or winch. This system is also often used on mainsheet systems too. There is only one winch used.
2. The yacht may have a headsail sheeting winch on both side of the yacht. The lines run forwards on each side to a point forwards of the mast actually not far from the bow. The lines then each go to the car and up to the sail. The sail has a block on the clew and the system is continuous. A kind of sub-set of this method is where only half this system is installed thus line runs from clew to car to bow and then aft to a winch. This is simple, but it sure can make a mess if you tack and accidentally leave a hatch open in the centre of the foredeck. The system above and below have less impact on other uses for the deck such as crew access and hatches.
3. The sheet is attached to the clew of the headsail, it goes to the jib car and then up vertically to a sheave in the front of the mast probably at 40% of the height of the mast. The line then runs inside the mast. It can be attached to a hydraulic cylinder inside the mast, or it can come out of the mast like a normal halyard and run to a winch.
The systems all have their merits. Our office favours the first one if at all possible for most applications. The continuous systems have a block on the sail, the 1:1 systems are dead-ended on the sail. Generally the clew block is not a problem because unlike an overlapping headsail it never hits the mast during a tack.
A commonly asked question is “does my track really NEED to have a curve in it; what should the curve be, up and down, canted, or a flat curve. The answer to this question does depend on a great many things. Firstly it depends on which of the three systems you have and the respective geometry of each system.
What on earth does that mean?? Well, let’s start at the beginning. Firstly, each of the three systems has a control line. This control line runs from the car to the centreline of the vessel and it controls the distance that the car can move each side of centreline; this controls the so called foot sheeting angle. Depending on track curve, the sheet tension will alter as you adjust this control line. Get the curve right and the tension does not alter as you trim sheeting angle; thus you don’t have to adjust the sheet during a change of course or during a tack.
Now in real life, as the car passes from port tack to starboard tack, the distances of sheeting and sail may alter. You can imagine that if the sheet goes up the mast to the second spreader or forwards to the bow then the various lengths must all change. Now this is not a problem provided the net or overall length stays constant. So, if the overall length stays constant then the sheeting tension will not alter and indeed you can tack and if you want to adjust the control line (at any time) you can and theoretically the sheet wont need adjustment.
Fore/aft sheeting is kept constant because effectively the track is inclined perpindicular to the forestay. The curve is there so that the sheet stays the same length, which should hopefully keep the tension in the sheet constant.
Some versions do not have a control line they just have an end stop on each side. This works fine, but most cruising boats don’t sail much close hauled and there are times when you want/need/should move the end stop further off centreline. Given un-controlled end-stop system then no curve is necessary since the sail is only sheeted in one position at a time. It may however still be sensible to incline the track perpindicular to the sheet lead, according to the track/car design. The clew load will generally be directed to a point half way along the forestay or even a little higher.
For any given system we (you) can usually achieve this with curve in the track. The track can sit flat and have curve in only one plane. The track can be inclined and have bend in only one plane. Or the track can have bend in both planes with/without inclination. There may in fact be an infinite number of bends that can achieve the right result in some of these (3) cases.
Well, I know this is sounding hard, but it need not be. Say we take system 1. The port and starboard leads will more or less cancel. The clew of the sail will swing in an arc perpindicular to the forestay. So, the track must be curved in both planes. BUT, if we incline the track so that the track is perpindicular to the forestay then we only need to bend the track in one plane. Not only that but it is the normal ‘thin’ direction of common RCB (recirculating ball) tracks.
This is in fact pretty easy. The radius of the bend is simply the perpindicular distance from track to forestay. The load from the sheet will NOT be perpindicular to the forestay it will probably be more vertical toward the middle of the forestay, but provided the car can accept the load at this angle there is no problem. With system 2 and 3 the sheet load and the clew load combine to give an overall car load whose direction must be found by adding ‘vectorially’. Generally you could say that system 2 should generate a lower load direction lower therefore closer to the bend plane or LP line and that system 3 will generate a load direction which is higher and closer to vertical suiting a flat non-inclined track bent in the thick (wide) plane of the track.
Moving along then let us discuss the sheeting tension. Probably as you go head to wind during a tack the sheeting tension will naturally drop off since there is no pressure in the sail, so the car will probably roll easily when unloaded. In any case there will be plenty of pressure to push it through once on the new tack. If you had a straight piece of track in the middle then this would be a short cut forwards of the curve and sheet would go even slacker. So, if you have to have a join or are limited by length of track to bend then a straight bit in the middle where you would never sheet is ok.
Extra for experts: I suppose if you want to maximise the foot length of the headsail toward 95% LP you could actually put in a modest reverse bend in the middle such that the self tacking track would have passed through the mast if it had a continuous curve.
Warning for everyone: Make sure your car will go around the curves without sticking. Make sure the manufacturer’s working load and warranty also apply to the radius of curve you are going to use. Make sure any track joins use proper joiners and that the track joins match PERFECTLY and will do so under load too.
Outside the critical sheeting regions on either side, you may determine that at such times as you sheet really wide that sheet needs to be eased to create a deeper sail. To save yourself making this trim adjustment you could slightly increase curve to slacken the sheet. It might still require adjustment but may be you can improve things. In a heavy boat you might sail a little below your proper course at a wider tacking angle with slightly eased sheet to build up speed again before tightening back up to close hauled. Actually, you might do this on every yacht.
So, overall, we have a situation where you can split up the jib track into a series of regions of sheeting angles from the bow.
from zero to 6 degrees a straight track would be ok.
from 6 degrees to 12 degrees you probably want sheeting constant.
from 12 degrees out to say 18 degrees you probably want the sheet to ease.
It will do no harm to calibrate your track and write degrees of angle from the tack fitting; with big numbers on the track/deck support so you can read these from the cockpit.
Lastly, you might put a padeye on the bulwark so that you can hook up a broad reaching sheet using MPS sheet for those occassions when the self tacking track is simply not long enough or where you want to run goose-winged…….
Knock downI was asked recently 10/99 if it was possible to make rig that would not fail if the yacht was knocked down and rolled. I had in fact just finished reading the book about the ’98 Hobart Race where many yachts lost their rigs and where several lives were lost. Consider a yacht totally upside down surfing sideways at about 30 knots with its rig fully immersed. The density of water is 1024 kg/m^3 approx and the density of air is 1.2 kg/m^3. This means that for 30 knots apparent the forces are some 1000 times larger. At the end of the day this comparison is a bit flawed but given what happened to what the Hobart Race author assures us were (equal to) the best yachtsmen in the world we do not think it is reasonable or possible to design a rig which can not be broken from such an event. We were asked to comment if current lightweight designs were a problem and older more sturdy rigs might be able to handle a knockdown. In fact a lighter rig with less inertia might be better if it provides less resistance to these irresitable forces, but the simple fact is that we do not know. That said there would be times with a yacht lying on its side that a new breaking wave would come along and pound down on top of it. In that case I am totally convinced it would be a good idea to have an overbuilt rig. It seems to us that making a rig some 1000 times stronger than normal would make it so heavy that the yacht was unable to function. In fact it might be argued that it is better to design a rig to break off above deck cleanly and simply so that it detaches from the yacht altogether (including rigging) so that the risk of further damage is reduced. I am reminded of instances like the ketch Hetairos which lost its rigs near Lord Howe Island. In that case the main pulled down the top of the mizzen too and the skipper was hurt whilst trying to dispose of the mess over the side before it was able to sink the boat.
Crusing Catamaran RigsIt is common for light weight racing catamarans to ‘fly a hull’ and use 100% of the available righting moment and at the same time reducing hull drag by removing a hull from the water. The overall “effect” is well known and the righting moment is generally the displacement multiplied by half the beam from hull centreline to hull centreline.The situation changes radically for cruising catamarans. Instead of a displacement of some 3 to 4 tonnes, a similar sized vessel may have a displacement of 12 to 15 tonnes. A four to five fold increase in displacement is not uncommon. The vessels are normally bridgedeck which affords a large volume for the nice things in life and each hull can contain various chest freezers and washing machines for live aboard comfort. This is in contrast to a racing catamaran with trampoline netting between two mostly empty hulls containing a few sail bags.So it follows that the righting moment of cruising multihull is some four times larger than a similar sized racing version and that the mast and rigging might become four times larger and more expensive. Not only this, but it takes considerably higher windstrength to fly a hull and that it would be outrageously dangerous to fly a hull in such a vessel at those windspeeds. So, this raises a number of interesting issues not the least of which is the refusal of owners to spend so much money on an enormous rig and the risk of capsize. We understand that in France it is common for rigs to be designed to withstand 60% of the righting moment. Given a factor of safety of 2.75x it would follow that if one were to fly a hull this is exceeding the working load (effectivley 166% of the working load). It can be shown this means that yacht flys a hull with only a small factor of safety of 1.0x at hull fly. Thus the rig should be close to falling down, but not quite… Hmm, anyway this is what we had heard. This is something of a compromise position which may work best for acatamaran which is relatively light in respect of cruising catamarans. NZ designers take a number of stances. One stance is to design for a wind range and whether this be 20% of the righting moment or 60% of the righting moment is irrelevant. Thus the rig is reefed at say 25 knots apparent windspeed, regardless of the displacement of the vessel. Whilst the windspeed varies between designers and projects this is in fact the same approach which is taken on multi-masted monohulls such as the huge sailing yacht Phocea (ex-Club Med). The argument is simple enough that where the righting moment is effectively infinite, then we might as well ignore righting moment; eventually at some windspeed the sail will shred and there is simply no point in carrying around enormously heavy and expensive masts simply to be able to fly a hull in (for example) 50 knots of wind. A further refinement of this is to put forward the proposition that it is most important that the vessel does not capsize. Therefore it is actually safer if the mast falls down prior to flying a hull. Thus rather than floating upside down offshore, the crew are left with a yacht floating the right way up albeit without a mast. For an offshore cruising catamaran of high displacement we think this approach has some merit and often engineer the rig accordingly under direction from the naval architect. Provided the crew reef the sails at the appropriate windspeeds the rig will never be in danger. However if full sail is left up the rig will fail prior to lift off. There may be a situation where due to mechanical failure full sail is left up unintentionally. Insurance companies of course take a dim view of rigs which are designed to fall down, and in general the wide variety of factors of safety and rig configurations make it hard to access which vessels represent a poor risk or indeed which are seaworthy at all.. The end result is that it is important to have good communication between owner, crew, designer, mast builder and insurer if the vessel is to be operated in a safe window with an insurance safety net to cover events which truly can not be foreseen. As if these issues of windspeed and righting moment were not enough, there is a similarly wide range of options for the actual rig configuration. This ranges from simple three stay rigs, either with or without multiple diamonds to keep them in column, to rigs which have really long swept spreaders in the style of the America’s Cup yacht KZ1 finally through to rigs with no spreaders or diamonds at all but instead have multiple sidestays and forestays. This last class of rig was to our knowledge used most famously on the english cat APRICOT, fifteen or more years ago. Recently the racing 60’s have moved back toward such spreaderless rigs. The cruising yachts do tend to follow the racing ones though it has to be said that many of the cruising yachts do not have rotating wing masts, so the reasons given for copying the racing versions are sometimes misguided. Owner sof mono-hull vessels are equally susceptible to this. The long spreader mono-hull KZ1 style rigs put massive loads on their spreaders and the spreaders sections then become almost as heavy as the mast itself, which quickly reaches a point where it becomes self-defeating.The good news is that with wide staying bases these rigs are always lighter than their mono-hull equivalents when operating in the same load regimes and the greater number of rig options provides for great flexibility to create an optimal rig plan for almost any type of sail plan on almost any catamaran configuration.
More on Crusing Catamaran RigsI was asked about what max AWS would you consider for a reefed case on a cruising cat? Here is my answer:
Hi, it is a tricky question to answer because depends how much it is reefed. I would say that if you have engineered the rig for (say) 26 knots AWS under full sail and fully powered up, then there is implicitly overturning moment figure (righting moment) that the rig is targetted for. Then after that point for each reef you can sail up to that overturning moment with higher winds. Eventually, the sheet loads will go through the roof, so once you hit that constraint, you miss the overturning moment target and are limited by strength of ropes, spars, beams, deck gear. Practically speaking I suppose we could say 45 knots is a more simple answer. If it gets windier than that it is not very comfortable, so you might as well turn on the motor and make a cup of tea.
Self WeightSelf weight is something more often than not overlooked by most people designing masts. Until recently ourselves included. It is fairly obvious to engineers designing concrete car parks (GRB would know this). For a small yacht say a 40 footer the rig might only weigh 100kg and the sideforces from righting moment are relatively large so the self-weight can be ignored. If however you look at the other end of the spectrum there are large yachts out there with rigs that weigh up to 20 tonnes. When one of these rigs is heeled to 30 degrees (in theory) the loading due to self-weight is 10 tonnes distributed along the mast. This has little effect on the upper most cap shroud, but it sure does hurt by the time you get to the bottom of the rig. Our view is probably that it is important ot consider this on all yachts over 100 feet long. The reason is that it is not just a case of having a lower or higher factor of safety to compensate because the effect is gradually increasing along the rig. Thus one would require higher factors of safety at the base compared to the top.. It took me a while to come around to this view. Best example I can give is that you have a yacht with near zero righting moment, the rig is so heavy that it practically balances the keel. Heel the yacht to 90 degrees and the thing sits there like a see saw. The flexural stress in the keel fin is mirrored by tension in the rigging and compression in the mast. The loads are high, but the loads from the RM are zero. Apologies to anyone reading this who finds this a bit too far off in boffin land.
GaffsSpeaking of boats a little more graceful I have been asked about gaffs. To be honest we have only ever worked on a single yacht with a gaff a rather nice looking 94′ yawl from the turn of the previous century being refurbished. The question is “do gaffs make sense again with the advent of carbon fibre?”. My thoughts are that gaffs can fill a role similar to a full length (carbon) batten. If you consider a mainsail and a topsail with a gaff in between dividing the two sails, then the net effect of the two sails is simliar to a large roach sloop rig with a single enormous batten. If the topsail and mainsail were sewn together with a pocket the gaff could in fact be a batten. The advent of smaller lighter battens and furling booms and higher strength sail cloths probably mean that on aerodynamics and weight the gaff is not quite so good and of course it is another moving part subject to wear, maintenance and breakdown. But putting that aside there may be cases where for a low aspect high roach mainsail that a gaff IS lighter than 6 full length battens and in any case now that battens and masts are often made of the same stuff it should be possible to build a gaff rig which is at least competitive against a regular sloop rig if done properly. Probably the real point is not that the gaff is only fractionally inferior but that there is no positive reason to go to the trouble of a gaff unless it is to remain in keeping with the original design/style. So, don’t write off the gaff as a waste of time, but don’t re-discover it either. If you agree with the length rule above, then the use of sail area and the limits on sail area become rather more pragmatic than in the current regime where every square mm is measured.
UpwashWhen sailing a fractionally rigged sloop upwind the boom may be sheeted on centreline, but the upper part of the mainsail will be twisted off and the luff will have camber in it. All this compounds such that the luff tape may be leading out of the mast at an angle of 45 degrees to the yacht centreline. If the sail is not backwinding in the top part it suggests that the apparent wind angle in the head of the sail is at some 45 degrees. Yet, the instrumentation is saying the Apparent wind angle is only 25 degrees. WHY IS THIS? Well the main answer is UPWASH. The wind curves down in advance of the sail. In general we can say that the more righting moment a yacht has and the more powerful the sails are then the more upwash it will create. By tacking back and forth and using other inputs it is possible to isolate upwash and remove it from the angle that the wind instruments measure. Clever systems are designed to do all this for you automatically as much as possible, so the average sailor does not have to think about it. Interesting observations about this are that if the upwash is caused by the sail shape and it is of the same order as the AWA itself, then anything such as a change in mainsail shape may in theory change the upwash and require recalibration of the whole system. Not only that but clearly there is a strong reason why it is that grand prix yachts use vertical wands for their wind gear: It is to get as far away from the influence of the mainsail as practically possible! Secondly, if the “local” apparent wind angle at the masthead is up to 45 degrees then the brands of vertical wand which are aerofoiled probably stall and cause lots of drag, and in fact the round circular masthead wands offer much less drag. This is the reason why AES designs round masthead wand tubes and we feel that the preference many racing sailors have for long narrow aerofoil wands is just plain wrong. Even with minimal upwash these aerofoils are likely to stall at angles of 25 degrees or greater. Very flat mainsails with little roach will create low lift, less upwash and these do have less luff angle. Whereas as a deeper high lift mainsail with lots of roach can create huge upwash (such as America’s Cup yachts). So without wanting to bore you with an advertisement, THAT is upwash and that is why wands should be round.
Yield StrengthsYield strength is a term given usually to carbon steels where there is a well defined point where their elastic hookean properties cease and they undergo plastic deformation or yielding. In most rigging materials made of stainless steel wire or rod the material does not have such an easily definable point. In materials such as this the data sheets normally refer to the 0.2% Proof Strength, this is the stress at which there is .2 of a percent of permanent deformation if you unload the part and go no further. So for a bar 1m long it has elongated 2 millimetres. For a stay 10m long it has elongated 20mm (0.75″). It is considered to be to all intents and purposes the same as yield strength for most design considerations. As an aside the 10m long stay which had permanently stretch 10mm would have not yielded by this definition. Not surprisingly, .1% proof strengths are often quoted too. Interestingly it is about 50% of 1×19 wire breaking strengths (typically) and it is usually between 60% and 80% of breaking strength for Nitronic 50 rod. 75% is typical and anything above 60% is getting dangerous. So, on a rig that uses wire, clearly you can not exceed 50% of the breaking load unless you want to tighten up the turnbuckles after EVERY sail. Not only this but sailing above 33% of breaking (66% of proof strength) is probably going to lead to short cycle fatigue. So, this gives a factor of safety of 3.0 At least when wire does fail it does so gracefully. The problem with Nitronic 50 rod is that although you might have a stronger stiffer rigging product, when it does break it is usually more of bang than 316 wire which has many strands and greater elongation before breaking. As a general rule rod stays can have a factor of safety of 2.0 and most stays need a factor of saftey of at least 2.5 or 2.75 from a yield/strength/fatigue point of view. It is not until you reach factors of safety of in excess of 3.0 that one can ignore strength and consider stays to have been selected on the basis of stretch/stiffness as opposed to strength. Typical factors of safety were discussed ages ago nearer the top of this page. UTS stands for Ultimate Tensile Strength and this is the Breaking Load on which factors of safety are normally considered/calculated.
Home Made Carbon MastsVarious home builders have asked for help building their own masts. Obviously, there is a wide range of techniques the professional mast builders use and for the budget builder the costs and the risks need to be carefully thought out indeed. Insurance of your finished boat is a topic in itself. Assuming that you have covered all the bases and want to do it yourself then you need to cover the basics. Here are some rough rules of thumb given in good faith with no warranty of any kind. Find an alloy mast extrusion which you know is safe and conservative and recommended by the yacht designer. This establishes a section size and wall thickness. Your carbon mast will be the same size and same wall thickness! It should be a tad stiffer made in carbon and it should be a lot lighter too. This is a very simple approach to avoid [evade?] doing the job professionally. Next step is a laminate, normally 1000gsm of carbon will laminate up to be about 1mm thick. So, if your mast is 3mm thick in alloy, then you need 3000 gsm of carbon. Carbon normally comes as 300gsm unidirectional, 200 gsm woven cloth 0/90 degrees, and double bias which is 400 gsm plus and minus 45 degrees. In general, the rule of thumb is that you use 60% of the laminate as a zero degree fibre, 30% 45’s, and 10% at 90 degrees. Next you need to have it balanced so that inside and outside plies are the same as each other, Next you need to try to distribute the 45 and 90 plies through the laminate. Generally, you start and finish with a 200gsm woven cloth because it is easier to drill and cut holes in the mast afterward if this is the ply on the surface. Given that you use the plain weave inside and out then you add the others as you need them to get near to 60/30/10 mark whilst keeping the laminate balanced and evenly distributed as possible. The double bias 45 is normally quite expensive if available at all. it is possible to make the mast entirely from unidirectional and this is often done. But keeping the outside and inside plies in plain weave cloth is recommended even if you use glass plainweave in order to save money and you don’t included the glass in your percentage figures. If the mast needs stiffening in some areas, you can add extra unidirectional locally to go up to 80% unidirectional. Conversely, if you have a lot of holes at deck/spreaders/stays then you might be wise to wrap the finished mast in some triaxial to really boost the off axis content in those areas, in addition to adding compensation patches to make up for the holes themselves. Masts that have long swept spreaders will sometimes need more 45 fibres (plus/minus) since alloy masts are in general far stiffer in torsion than carbon ones. Hopefully I have not confused you. There are some other issues to be wary off, and I hesitate to try to write a full design manual, but in particular local buckling can happen if the wall is thin/flat, but if the alloy mast extrusion you are targetting is NOT extreme, then all should be fine. Obviously if your mast is small the costs and risks are low and if it breaks you can stick it back together and add more carbon next time too. If on the other hand the boat is big the costs are large, the risks are large and the relative cost of professional engineering from AES or any of the other design professionals is relatively low by comparison to the cost of getting it badly wrong. Yes, I know the Titanic was designed by professionals, but a number of people have misjudged the work involved in building a carbon mast and with hindsight have wished they had thought it out better. So, research the whole thing thoroughly from every angle before you start and then it will either go very well or you wont attempt it at all. Both of those two outcomes are fine if they result in many years of trouble free sailing where everyone has a great time.
Finally, a confession, I don’t strictly practise all that I preach, it takes a little interpretation. I sail a Farr 3.7 and my current boat has rather an old carbon mast homebuilt by one of the former owners, at least three owners prior to me. The entire boat cost NZD 2000 (bottom of the range and good for a learner). The mast is made from several windsurfer masts in the 80’s era. This mast has clearly broken before I owned it, to date it has broken three times in my tenure, not solely due to operator error; but mostly. The mast has never broken at the same place twice (so far) and is developing a patchwork-quilt look… Having sleeved and joined it back together three times, including coving on a whole new bolt rope groove once, it has to be said that repairing a carbon mast is much easier than repairing a broken aluminium mast and I am getting quite good at it. I race once a fortnight and it takes one week of lunch-times to effect a repair to a big break. Working for AC teams (mostly NZ) various masts have broken, thankfully mostly in training mishaps. In each case the teams have not had insurance (it is not realistic for this kind of operation) and in each case the mast was repaired with almost zero weight increase or change in performance characteristics. A lot of prattle is spoken over the yacht club bars of the world about this sort of thing. The truth is that it is cheaper, faster and better to repair a broken mast nine times out of ten, assuming the mast was basically fit for its purpose. Owners and insurance assessors tend bring along a lot of baggage when negotiating over this kind of problem. All that said, my own dinghy mast is a bit of a poor example, and should be put out of its misery; I only keep repairing that one out of interest: a bit like a ‘cat playing with a mouse’. If you enjoy your sailing and you enjoy experimenting with your rig, go for it. Best advice I can give you is to choose a boat/class where the costs are within your ‘leisure budget’, that is to say, DO NOT buy a boat that you can’t afford to actually have fun with because you paid so much for it that you daren’t spend any more on it or because you are afraid to break it. Buy a boat that costs only half of what you wanted to spend, and don’t spend the other half unless you can make a genuine case for its improvement.
The Whitbread 60 rules included a strange rule regarding the top mast stays. Our office was working for the Swedish Match Team and developed the so-called cathedral rig to get around the (rather silly) rule requirements trying to enforce jumpers. This cathedral rig configuration was then IMMEDIATELY adopted by all the big teams re-rigging their new masts regardless of the expense (Merit/Dalton) being the first to see it were the first to change. The Volvo then followed this..
The AC booms (circa 2000) were reasonably deep and the shear requirements for the side walls are quite low compared to the lightest weights of uni you can buy and this needs careful use of core even then, to make it work right. So, the lattice booms developed by us for the 2003 Team NZ campaign made a weight saving by eliminating the core, glue film to attach the core and by eliminating much of the excess side wall laminate weight too. The downside was that we had a few break while we figured it out, and the pipes need fittings made at the corners, the upside was that they were really really cheap using high quality pipes made by Kilwell and not forgetting the drive and professionalism of Nev, Taro and the 2003 shore team to put them together. In the 2007 campaign almost every team had copied this innovation to some degree and some with considerable style as well. Imitation being the most sincere form of flattery, we were stoked.
One day I should write about twin rigging, triangular poles, X rigs and pushers and maybe even the simplest engineering structure on the boat.
Rules like the AC Rule
These rulemakers and measurers ‘we’ have keep writing rules in the mis-guided attempts to keep the costs of the AC (or volvo or whatever you want to enter here). The truth is that the fundraisers raise as much money as they can, the “expense” of the Class is used as a lever to obtain more money and the real costs are in getting around the rules to spend it. So, having raised as much money as one can, then one spends it the best way (one can) to get the fastest boat. Making the keel/hull out of cheap lead/carbon instead of expensive lead/carbon or some other such rule will simply leave more of the money for figuring out how to make a lead/carbon right on the edge of the rule. Thus the endlessly growing complexity of the rules is GREAT for engineers (innovators) because we’re kept fully employed looking for ways forwards in a highly constrained albeit contrived design space. It also keeps the rule makers and measurers fully employed, and guess what, they need paying too. Nobody ever has explained to me how a 1992 AC boat was cheaper than a 12 metre. I suspect that 90 footers wont be cheaper either. By bringing in various other rules (window dressing) we are told this saves money. Does this mean that money is then returned to sponsors such as emirates or BMW? I don’t think so. Does this mean that total campaign budgets will drop and that teams will ask for less money? I doubt it. Well how, exactly, is it saved then? Does it get donated to charities, maybe a tiny bit did (out of the PR budget), but that happened regardless. The cost of a campaign is certainly enormous and the smaller teams without the big bucks have been shown to be inadequate. But the teams that manage to raise the big money will always be fastest, have the best design and sailing talent and WHATEVER is the rule they will move heaven and earth to beat it (and we will be doing a great job of helping). Unless you can find a way of limiting the dollars with a budget cap (various sports try to do this) you just aren’t going to get there with the rules. Generally the team with the most money and the most control of the rules is the team that just won it. So, don’t expect them to throw away this advantage. Does this technology trickle down to mainstream yachting? Well, thanks to the totally distorted rules that outlaw any sensible improvement and create weird stuff instead, the amount of trickle down is a tiny fraction of what it should be, because it is impossible to apply to a normal boat. If the rule was 70 feet long, with a monohull and some practical limits on beam and draft then it is hard to say where it would all end up. It would certainly be very frightening, to begin with. The only AC team I have ever worked with on this basis was the 1988 big boat challenge (90 foot waterline 21′ draft etc). This boat was very much in the spirit of the Cup. I personally liked and admired the Connor catamaran, but I would never have entered a catamaran in that event based on what I think the event stands for. I think a 70 foot version of ‘limits’ in the same style as the 1988 K boat would be the way to go. I am sure all the measurers are really very knowledgable yacht designers and could in fact find other useful employment as such. Instead of the negative rule beating approach, we could develop a postive make it faster approach. The current owners of the cup are going to create a new rule with Tom Schackenberg in charge (at time of writing), it has to be pointed out he too was a major player in the K Boat design for Michael Fay in 1988.
Parting ShotWe have made up all of the above due to questions we have been asked or problems we have faced. Don’t forget my (complete and utter, total) disclaimer at the beginning!! Please do not hesitate to suggest a topic or ask questions, try to frame it so the answer could be of interest to others too. Cheers, Chris.