Sailing Techniques and Experience
Kevin Ellway. Upwind we're starting to twin wire at around 9 kts and were fully out in 12 knots. As soon as we get properly wired the speed increase upwind was huge. We just reeled in Tristam Jacques' 29er (top boat): we pointed high and sailed at 0.5 - 1 knot faster - and that's a lot when your single wire speed is around 4.5 - 5 kts. Basically, if you can sit on the side and you are just starting to lean your shoulders backwards, you can twin wire. The technical reasons for this I will explain later.
In other races, when the wind is 13 - 15 knots, the upwind speed is something else. We are on pace with 800's and almost there with 49ers, and I'm talking about top of the fleet boats here. Make a bad start (common in my case) a 'quick?!' Laser 4tonner is in the way. Just foot off slightly, dive to leeward, pass it in a few seconds, then point back up. You're now to windward and sailing so much faster it's embarrassing. You just feather the boat up in the gusts so the jib tell tales start to lift and sail with them fully attached in the lulls. The boat is fully planing all the time and generating its own apparent wind.
Ben Brown In light airs we found that the helm trapezing in the light stuff with the crew comfortably perched down to leeward but still fairly well forward felt very fast. Daryl felt that it was more comfy because your not scrunching up the harness into your gut. The main advantage was the transom was nicely out of the water and comfort incomparable to sitting on each other on the same bit of side deck. Taking from wire to wire smoothly was a bit of an issue so we tended to bang corners which I don't think pays in the light stuff. However with practice and a better boat layout I think this would improve.
In the medium airs it seemed to pay upwind and were able to power up more and for longer than single wiring. Down wind it was more tricky for both to stay out on the wire, without going really high and not very quickly.
Our experience is a bit more limited in a strong breeze but we did get out at Stokes on a couple of reasonably windy days. Upwind - it felt really really fast, much easier to keep the power on and the boat trucking through the chop. We gained significantly on LRN and NB who were upwind of us on several occasions. Need to interlock legs to stay close enough together which was a bit unnerving at first but you get there.
Gavin Sims In marginal single wiring conditions I prefer to have the crew move in and out on the wire with the helm in the boat concentrating solely on sailing, I feel this is quicker as the crew can move in and out quicker and more smoothly as isn't holding the stick. Downhill we've found it actually pays to both twin, you have to sail really high but the speed seems to more than make up for it, especially the lumpier/choppier it is as you tend to sail through and over it rather than bobbing about.
When the wind is greater it sort of gets easier as you can stay flat out playing the sheets to keep it level.
Upwind I prefer to take the mainsheet (off the boom) as it helps me keep my balance (something pulling me towards the centreline). To tack I pass the mainsheet to my tiller hand, grab the trapeze handle(well I would if I had any so just the adjuster rope purchase for now) with my forward hand, unhook, step in and push the tiller at the same time. The crew should also jump in as well. Then the crew jumps out first and I join him when everything is settled and the boat is moving nicely after the tack. When I don't make a mistake this is the fastest way to tack, but easy to make a mistake. When breezy sometimes it feels like your kicking the stern of the boat around, that coupled with the turning moment from the rudder just makes the boat move away from under you, but practice will sort that out.
It's amazing how much sail you realise you aren't pulling in when sailing upwind, even in 10 knots of breeze, with 2 on the wire you can really sheet everything in and down hard. This does however load everything up more, webbing straps on my boom that used to last a season at least now last a month or 2, then the boom snapped.
Jim Champ Speaking from observing others, mostly Gavin and Ben, I'm not sure that the dramatic increase in upwind speed that everyone comments on has been that apparent to me. Gavin disappears upwind from the Bistro in the moderate stuff, but then he did anyway, and in a really serious breeze we seem to be able to hold our own, and to date we haven't felt any problems with straight line speed against Ben and Daryl upwind. But on the other hand as several folk have noted, Halo has the greatest differential between helm and crew weight of any boat in the fleet. As we are tuned for upwind speed and have I think got a lot quicker through the season as we sailed together more and got the new rig tuned up maybe the performance increase is somewhat masked. With the weight differential and because Alex goes weight training and hikes hard we're much closer to the two string righting moment than those teams where the helm is closer too or even heavier than the crew. And of course there's the practice factor too - as people learn how to keep the boat really flat without teabagging they can only get quicker, so it may be a different story over the summer. And if its more fun does it really matter if its not any quicker?
I think at Weston in April 2004, when the breeze was on the light side most folk reckoned that although Mango could get on two strings virtually as soon as one, when they did so they were losing so much height that it wasn't really paying. On the other hand on the one lap there was a half decent breeze they were certainly flying although I don't think any of the rest of us would have looked to hold onto them in those conditions anyway.
Kevin Ellway And now for the fun bit. What happens downwind? You are sitting on the side, thinking of hiking and you're going fairly fast. Just luff slightly as you step onto the side. You're out. The acceleration is truly awesome. We reckon an instant 'turbo boost' of 5 kts boat speed. And as this speed kicks in you have to bear away, so you end up sailing deeper than you were before. The boat feels incredibly responsive and lively. It almost like shortboard sailing in a dinghy. It's fantastic. And I'm still talking about winds of less than 14 kts as measured at Stokes Bay club house. And that's on a big tall pole.
Ben Brown Downwind is damn right scary but a great ride. We managed to pull off a couple of hoists with me partially wiring. That felt seriously good and got the power down very quickly.
Jim Champ The really suprising thing, especially if like me you're not a regular Cherub helm and do most of your trapeze helming in singlehanders, is how difficult it is to keep your feet on the gunwhale downwind. No, not so much swinging round the front (although you'll do that too!) but because the mainsheet loads are so light (at least in moderate stuff) and the tiller maybe tends towards lee helm if you're hunting for power to keep you out, then there isn't really anything you can pull in against! So you need foot loops. Put them on! The helm maybe wants to trapeze higher than you might think, although the fashion these days is to trapeze much higher than I was taught. But of course the most important thing is to anticipate what the boat is going to do, so practice, practice, practice!
Gavin Sims Hoisting - The helm staying on the wire whilst the crew hoists isn't the fastest way of doing it we reckon. It causes you to sail too high and oversheet the main. Also as soon as the kite is out the chute it's in breeze instead of being semi-blanketed behind the main and is much harder to hoist fully. I tend to come in with the crew for the hoist, but stay clipped on, then as soon as the kite is up I jump out, just beating the crew by a second or 2.
Gybing - Just like tacking except pull the tiller towards you. If standing at the back of the wheelie bars (aft gunwhale extensions) it can seem a bit weird having to have to move forward a fair bit to actually make it into the boat, especially when the crew doesn't seem to want to move forward. If you let the crew out onto the wire first I find it more difficult to join him/her as the boat is moving quicker and bouncing a fair bit.
Dropping the kite is easy, just be a little further downwind than normal. Crew jumps in and pulls it in, helm stays on the wire, firstly bearing off as the kite is dropped, then having to luff a fair bit to keep his lard from dragging in the water.
To me it's far more fun, the speed you can achieve upwind is superb, and if you can keep it up on a 2 sailer in some breeze is something else.
Kevin Ellway. Having tried twin wiring the Cherub with all up crew weights up to 22 stone, I can make the following comments:
My recommendation is just to go and try it. Have fun!
Ben Brown - Twinning adds a new dimension to cherubing and each time I have tried it I come off the water with a massive grin.
Will Lee - Here are my memories of twinning on Patrick's boat in a flukey f3 in the solent in September 2003:
That day I went as a person who thought that it would be too difficult to twin on a 12 foot boat, and left a compelete convert. This is the pattern: Everyone who has actually tried it loves it. It is completely within the ethos of the class and puts us beyond the masses in terms of performance, which is where we belong.
Gavin Sims
Since fitting the wheelie bars have discovered something else when flat wiring right at the back of them with the kite up, the rudder ventilates (nothing new there), but get it to grip back is super difficult. I think it must be because we're both stood right at the back (my back foot is just behind the trailing edge of the rudder) and flat wiring so putting a lot of side force through it or something. But it has been gusty and fairly confused when this has occurred and normally resulted in a swim fairly quickly.
With both crew out of the boat and on the wire the boat is much more lively, as the majority of the all up sailing weight is now a few feet to windward of the gunwhale. You can feel the boat respond so much to foot pressure and it seems to leap and plunge around more.
Getting some are of a steep wave upwind does make you wince a bit when you think that there is now the mass of both crew compressing the mast as the boat lands with a SLAM. But no worse the single wiring downhill in some lump.
If you make sure everything is up to the task then you should break no more than previous, just be prepared for some (more) swimming.
So why does twin wiring have such a profound influence on performance?
It's all about power to weight ratio. With 1 wire, p:w is around 32%. The second wire adds about 25% more leverage if helm and crew are of equal weight, more of the crew is lighter (as is often the case). With 2 wires the p:w ratio increases to around 40%. With the exception of an 18' skiff, this is way higher than any other dinghy, even 49er's, and restores the Cherub to where it belongs: at the top of the performance tree. More importantly though, is the fact that a p:w ratio of about 30% is required to get planing to windward at all. At this ratio, planing is marginal and very sea state dependent in such a short boat. This is what the single wire Cherub is like. Add the second wire, and it just can't help planing to windward.
Q Why, if we're adding 25% more leverage don't we need 25% more wind to utilize it?
A There are two reasons. The first is that wind force is proportional to wind speed squared. So a 25% increase in wind force is, for example, an increase in windspeed from say 12 kts to 13.4 kts. The second reason is that downwind and particularly upwind, we don't sail on true wind, but apparent wind. Say at 12 kts of true breeze we make 4.5kts at 45 degrees to the true wind. This produces an apparent wind of about 15.5 kts at an angle of about 30 degrees. Now if we twin wire and push the boat over its displacement resistance hump and get it to plane, let's say we are now making 6 kts. The apparent wind is now at around 17 kts, and thus has a force of 20% more, and you're using most of the leverage of the twin trapezes. As the true wind increases, the affect is even more profound. At say 14 kts of breeze, single wired you'd be marginal planing at around 6 kts. The apparent wind would be about 19.5 kts. If you twin wire, your speed will increase by at least 2 kts (and that's conservative). The apparent wind increases to 21 kts, which means the wind force has increased by over 25% and you're flat stick wiring. This theory is entirely borne out by practice.*
Q Doesn't twin wiring put more strain on the mast and boat?
A No, the compression loads on the mast are if anything less twin wiring than single wiring. This is because Cherubs tend to use high rig tensions and the tension in the windward shroud is reduced by twin wiring. The load in the hull is also reduced because it is not having to transfer the helm's leverage as torque through the hull. The peak dynamic loads on masts occur during a nose dive. If you stay in the boat you put a big force on the rig. Twin wiring, and you've already gone round the front and into the water so there's no load on the mast! Twin wiring will benefit lightweights The Cherub is only 12 ft long and has a very high DLR (displacement length ratio). At 19.5 stone crew weight it's around 125 compared to less than 70 for many of the smods. This makes it 'push water' in displacement sailing and gives it a big resistance hump nearing planing speed (5.5 kts). As you put more weight in it, the size of this hump gets very big. The Cherub never has been, and never will be, a heavyweights' boat. Sure, if you're heavy you can win races in force 4 plus. Why? Because most of the time you're planing. (My brother and I have won several handicap events at the new PY in the slug laden with 24.5 stone.) If you're heavy and you choose to sail a Cherub, you do so because it's fun, not because it's the ideal size of boat for your crew weight for competitive racing. There are plenty of other classes for that, but precious few for crews under 21 stone. Twin wiring will not affect your relative competitiveness. But you will have far more fun.
This section is a combined effort!
Adding the actual trapeze wires is reasonably trivial. If your trapeze wires end in T terminals the easiest option is probably to buy a ring ended T terminal like the Holt Allen HA6180 and buy some rope trapeze wires. We suggest 3mm spectra/dyneema rope, although there are more sophisticated alternatives if your wallet can stand it. Now fix a bulleseye or turning block to he floor, about midway down the cockpit floor, and about 20cm off the centreline each side seems to be about right. Too far forward and the crew will curse you for being eternally wrapped up in them, to far aft and you'll be too far back when tacking and gibing. Too far off the centreline and they'll hinder you in lighter airs when trying to slide along the tanks to the front. If you have a tunnel then at the back is good or use the toestrap fixing points if you don't.
Thread a piece of shockcord from one trap line, through the relevant bullseye in the floor, to a suitable turning point fwd or aft (centre brace of the gantry perhaps?), back to the bullseye the other side and attach to the other trapeze wire. Make sure you have enough shockcord so that you can trapeze right at the back of the boat and up by the shroud plate without the shockcord being overstretched whilst still being able to pull the trapeze lines taut when not in use.
As far as the rig goes the popular belief that compression loads increase is not in fact true for most rigs. Because the trapeze "shroud base" is so much wider than that of the shrouds the compressive load if anything can reduce. The main problem is with spreaders and the support of the rig. A modern masthead spinnaker rig with cap shrouds, check/D2 stays and plenty of rig tension will be fine and needs no changes. If you have rather less rig tension and a single spreader rig then its another story. The problem is that when you both get out on the trapezes then the windward shroud tends to get less loaded and the leeward shroud more loaded. Consequently instead of holding the mid mast stiff down to leeward the spreaders actually make the mid mast flop up to windward and dump all the rig power. The lateral support on the mast also generally reduces with more risk of S bend effects and possibly failure. Consequently the rig is both less powerful and more prone to break. The cure for this is to lock the mid mast in position with Check stays/D2s. These are wires (or vectran/dyneema) led to the base of the spreaders. The spreaders are raked back so that they are pushing the mast forward and in, and the check stays pull the mast out and back. Thus the mast is locked in position with moderate mast bend. The downside of this is that if your rig depends on the mid mast bend for gust response it will become less responsive, but you'll just have to live with that!
The sideways load on the daggerboard goes up at least 20 percent. There are daggerboards around that will not survive this (mine for instance I fear). Be careful - or get the carbon out!
If you have centre main then just buy/make a longer tiller extension, if you have stern horse with sheeting off the boom/floor near the centre of the cockpit then you'll twin tiller extensions. Don't use telescopic tiller extensions. If you unjam it out there you really have very few options unless you get it to grip again very quickly! One minor niggle with having 2 extensions is that the unused leeward extension is always flapping about in the water and spray pulling and pushing to what seems the opposite of what the helm is trying to do. Make sure the tiller extension you're using isn't too long. You need to be able to pass it in front of your trapeze wire when fully out because it makes playing the mainsheet much easier.
Patrick has discovered a really good option for tiller extensions. these days anglers use long and very light carbon fibre rods. if you go to your local tackle shop you will find that they sell fishing rod bottom sections at suprsingly low prices that make excellent tiller extensions.
Oh yes, and beware twin tiller extensions on other people's boats. Its extremely irritating to duck a starboard boat's transom and then realise you've just clipped their tiller extension and you've got to do a 720. Trust me on this!
There may well be some mileage in looking again at mainsheets. Davro, always a fan (in fact I believe the inventor) of using a post in the middle, thinks that a transom bridle and sheet off the boom works better because there's less clutter when running across the boat and either crew can take the sheet. This makes twin tiller extensions compulsory of course. If the crew talkes main and jib through the tacks the helm can concentrate on standing up and getting on wire and staying vaguely on course. With self tacking jibs the main and jib sheets spliced together to aid this. And apparently the cunning use of shock cord stops the whole lot f**king off out the back of the boat or down to leeward when you drop it.
Depending on what arrangement you have within the boat you may want to alter the position of your control lines to make it easier to use from the wire. Gavin previously had the jib sheet, kicker and Cunningham all coming off one flip-flip type thingy below the mast just below foredeck level. However this meant the kicker attachment point was above this so pulled at a very shallow angle. Sailing twin wire they found they needed more kicker so decided to move the kicker attachment point down as low as possible. This meant moving the control lines and jib sheet. The control lines were moved to the centre of the cockpit floor and lead to either side, where hopefully they'll be easier to reach in some breeze.
You may also want to add some kickbars to the cockpit floor and/or sidetanks, this depends on the geometry of your cockpit and how you actually get out on the wire. With a deep floor and wide tanks it can be a big step/jump from the cockpit floor to the gunwhale with only an expanse of shiny sidedeck between, making it almost impossible for the helm to get out if he's clipped on and the boat is heeled to leeward.
An extra footloop right at the back of the gunwhale for the helm is essential, just to keep you in place when it starts getting breezy and lumpy. You can also extend the gunwhales aft behind the transom. Gavin will tell you he never properly pitchpoled my boat until they'd fitted the extra string, and with a proportion of the helms weight acting through the base of the mast instead of solely wherever his backside is you do end up with a slightly less bow high trim compared to single wiring. If you do extend the gunwhales then Gavin strongly suggests following a tip from the 12ft skiffs and angling the extension in towards the centreline by 10 degrees, as this drastically reduces the tendency for elvis leg when at the back.
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