Another little conundrum for the hive mind..
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Category: Dinghy classes
Forum Name: Dinghy development
Forum Discription: The latest moves in the dinghy market
URL: http://www.yachtsandyachting.com/forum/forum_posts.asp?TID=10348
Printed Date: 19 Jul 25 at 3:02am
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Topic: Another little conundrum for the hive mind..
Posted By: iGRF
Subject: Another little conundrum for the hive mind..
Date Posted: 06 Jan 13 at 6:42pm
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Well, I've switched my little EPS to rear sheeting, and done away with all that silly rope in the middle of the boat nonsense back to the way life was in my first ever single hander the Blaze, with a neat little auto block from Ronstan right up the front near the mast and everything is now cool, except I shall have to learn another tacking technique which doesn't involve teeth, but that's not my problem.
My problem is as follows, one fundamental in windsurfing is that you sheet into the centreline and slam the foot of the sail as far back down on the boards as possible to go upwind, which was my secondary goal with this sheeting method. I've even fitted an adjustable forestay to further emulate it. But... It doesn't work, the boat goes slower, why is this? Is my question for speculation, why is it Laser style boats don't work centre sheeted? |
Replies:
Posted By: Dougal
Date Posted: 06 Jan 13 at 6:59pm
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Camber induced windsurf rigs have quite a large angle of attack so when the rig is sheeted right in, the angle of the sail to the wind at the luff is still quite wide when compared to a dinghy rig. There may also be an apparent wind effect because of the higher speed of a board compared to a dinghy. Sheeting to the centre line works on a 2 person boat because you have the jib that is changing the wind angle over the bulk of the main. This is how I have always thought it, but happy to be corrected if needed! ------------- What could possibly go wrong? |
Posted By: JP233
Date Posted: 06 Jan 13 at 7:23pm
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You have switched it TO rear sheeting? ------------- Thanks Jamie |
Posted By: iGRF
Date Posted: 06 Jan 13 at 7:34pm
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Hmm, time was we used to use soft sails and it still followed, in fact we used to actually over sheet at times in certain conditions on certain types of board, and this EPS rig isn't that unlike a full battened sailboard rig.
It was a bit of a funny day today, misty, light wind, which the EPS and that rig don't really like when the wind drops below about 3-4 knots. My expectations were more speed and better upwind, but the further toward the centre the more it slowed, I had to try it over a bit of a period to check it wasn't just the wind dropping or a lift that allowed both a Laser and a Supernova (my normal wednesday afternoon opponents) to overhaul me. It just doesn't seem logical to sheet out to go faster, but today that was what was going on so I shall have to adjust my rear sheeting thing which at the moment has a fixed block dead centre, to more of a traveller arrangement like those fitted to the back of a Laser. In fact I noticed on the Guy with the Rooster, he had a natty rudder arm bit the wiggle thing attaches to with a roller on the top to allow the traveller to go over it, and carbon, very natty, where do they come from I wonder, I should have asked but when I saw that i hadn't realised I'd be going slower not faster at that point. |
Posted By: iGRF
Date Posted: 06 Jan 13 at 7:36pm
Yes it was centre sheeted. |
Posted By: Rupert
Date Posted: 06 Jan 13 at 8:23pm
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JP, rear sheeted then up the boom and off a block on there, rather than my old fashioned favorite Firefly style aft sheeting. GRF, if you sheet in too much the sail simply stalls. In the Europe, I used to have to sheet with the boom actually outside the boat at the stern in a real blow to get it to go fast. Oddly, the only exception I've found to that was with the wishbone boomed 1980's windsurfer style rigged Tonic, which would sheet to the centre with no trouble at all. Never understood why, but maybe it is a function of the sail design needed for a wishbone rig? ------------- Firefly 2324, Puffin 229, Minisail 3446 Mirror 70686 |
Posted By: craiggo
Date Posted: 06 Jan 13 at 8:27pm
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Graeme, if you can sheet out and keep the sail filling it will always be quicker than oversheeting. Its basic physics. If you look at the force vectors from the mainsail if it is over sheeting you will have virtually no forward component, only sideways and therefore slow.
The roller on laser tillers does indeed allow the traveller to be tightened right down but this is not to prevent the boom moving out to the quarter, it is to allow the leech tension to be maintained against the rather bendy mast. Even with the super tight traveller the boom on a laser is over the rear quarter when fully sheeted in. In most single sail classes this tends to be a good approximation for the best upwind position. As has been said on two sail boats you can drag the main up to the centreline but only because the flow angle onto the mainsail is altered, and most of the forward drive is developed by the jib. The other thing to remember is that in light airs you need to sail free to maintain attached flow. Dinghy sails tend to collapse and therefore struggle to re-attach whereas more rigid windsurfing sails can quickly re-attach the flow. The other thing is that with light winds there tends to be a very thin boundary layer therefore there is a large pressure and directional gradient acting on the rig, so you want to allow a fair amount of twist in the rig. As the wind speed picks up to 7-8kts the boundary layer gradient over the height of the rig will be less and therefore you want a tighter leech. There are other reasons such as rotational centre of effort of boards vs dinghies, and position of foils which will also dictate rig set up. From what you have said, I would say you were oversheeted and pointing too high. If you compared your actual track across the ground I would imagine that even though you outpointed other boats on the lake they probably sailed a higher course??? |
Posted By: Telltale
Date Posted: 06 Jan 13 at 8:53pm
Yep, I think you will find that quite a few RS300 sailors ex and otherwise will confirm that as well, boom out to the quarter to get it to go.
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Posted By: blaze720
Date Posted: 06 Jan 13 at 9:24pm
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yes yea ...single sail set-up .... about 30-35cm from centreline works best for the Blaze in terms of VMG and I suspect the EPS is not that much different. Tighter can work in a tactical sh*t-fight with a real pain in 'the whatsit' in his or her 'pinch and fight' traditional box but long term all around the course a bit lower works best for boat speed ... and handicap. But you might have known this already .... Mike L. |
Posted By: winging it
Date Posted: 06 Jan 13 at 9:26pm
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yes, the megabyte has an ultra flexi rig. To make it go I have to pull the traveller up to windward but not sheet the boom inside the transom or it all stalls.
------------- the same, but different... |
Posted By: Jack Sparrow
Date Posted: 06 Jan 13 at 9:34pm
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Try a split tail main sheet it will allow you to center the main without over sheeting. ------------- http://www.uk3-7class.org/index.html" rel="nofollow - Farr 3.7 Class Website https://www.facebook.com/groups/1092602470772759/" rel="nofollow - Farr 3.7 Building - Facebook Group |
Posted By: iGRF
Date Posted: 06 Jan 13 at 9:45pm
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Well (in answer to Rupert) sail design of windsurfer rigs has changed a lot, but the sheeting position hasn't really, but one thing we always had was sails that twist off at the top more than any dinghy sail i have ever witnessed to date.
We also never had the luxury of the kicker (one thing I didn't try which might work better was sailing with no kicker then centre sheeting). As for craiggo as excellent an explanation as I could wish for, it still doesn't get to the point, a sail can only really sheet against the wind to the point of luffing, so surely all the actually sheeting angle does is align the boat closer to that sailing angle, hence the logic it should sail higher. OK higher is not necessarily faster, but in light weather usually the best and optimum tactic. So yes I was over sheeted and pointing to high, yet not pointing as high as the Laser and the Supernova (who I normally out point and did once I resumed a sheeting angle close to that which the boat normally had with it's centre sheeting. I've spent all day today trying to work out the logic of it, obviously the sail is a backward design as all dinghy sails are to my mind, without the ability to twist the head by cunningham and mast bend. The second point I'm probably missing is that with a board the rig has to constantly be at the optimum point just aft of the centre of lateral resistance which of course a boat doesn't because the aft foil players a part by steering the boat. I need to think it through some more as I have a new sail on the way I might want to alter a bit, anyway it's an interesting problem I need to solve, to make this boat work better in light wind. |
Posted By: BBSCFaithfull
Date Posted: 06 Jan 13 at 9:53pm
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You are wasting your time Graeme. ------------- Greatfully Sponsored By www.allgoodfun.com Int 14 GBR 1503!! |
Posted By: tick
Date Posted: 06 Jan 13 at 9:59pm
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This is where I extol the virtues of the Byte c2 and presumably Megabyte. Centre sheeting with a traveler. Little kicker and haul the traveler to windward to put the boom near the centre. To open the leach put on Cunningham which is about 12 to 1. The progresivley flexible mast does the rest. If it had transom sheeting it would close the leech. Up wind Byte sails look very flat but they are open in all the right places. I think if you centre sheeted a Laser the boom would break in half. PS. I told you to buy a Byte......it would have pressed all your buttons!
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Posted By: Daniel Holman
Date Posted: 06 Jan 13 at 10:00pm
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It's a degree of freedom problem Graeme.
Optimum sheeting angle is a big subject and a function of speed, efficiency etc. On most sh boats of roughly eps speed, you want the boom at 9 degrees to the centreline unless you're starting to overpower, when you sheet out to 14 ish in extremis. Go inside 9 deg for anything longer than to shoot a mark and you'll go sideways. Quicker more efficient single sail boats like cats or in extremis iceboats sheet closer than that but if have to go into tedious theory to explain. Remember that on your board, the rig has 3 degrees of freedom about the UJ. If you have the foot running on the cl and the rig is totally upright, the Aoa will be zero (assuming no twist) all up the rig. Assuming the foot is not at 90 to the luff, which on a board sail it never is, then as the rig is rotated (about the foot ) to weather, the Aoa of the rig increases as you go up the rig. Job headed mainsails generally get sheeted to cl or even above sometimes, but think of them as trim tabs behind a jib - jibs generally do most of the work upwind, and get sheeted at similar angles to una rig mainsails. |
Posted By: tick
Date Posted: 06 Jan 13 at 10:03pm
But can you not open the leech with the cunningham? When it is blowing athletic Byte sailors sheet hard and hike hard. Is the Megabyte mast carbon?
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Posted By: ex laser
Date Posted: 06 Jan 13 at 10:05pm
since when did g.r.f listen to any of us. we all know nothing!!!!!!!!!!!!!!   ------------- |
Posted By: JP233
Date Posted: 06 Jan 13 at 10:25pm
ohhh, gottcha, i was going to say, he really has gone mad! ------------- Thanks Jamie |
Posted By: iGRF
Date Posted: 06 Jan 13 at 10:35pm
Yes and no tik, yes about the rig, not so sure about the length of that boat and anyway I could never have found one for seven hundred quid, so it's just a question of trying to make a rig as good.
I wouldn't go as far as to say nothing, hence my frequent enquiries as to the perceived wisdom which I always take on board, before deciding yes of course it's wrong and or there might be a better way.. That's how things progress.. |
Posted By: iGRF
Date Posted: 06 Jan 13 at 10:41pm
He we go again, none child friendly expression enough to test the patience of Job(e) So c'mon keep coming on here dropping expressions the natives don't get yet wouldn't dare ask for fear of being exposed as ignoramuses like me.. 'Job headed?' Pay attention now ladies we're all going to learn something again.
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Posted By: ex laser
Date Posted: 06 Jan 13 at 10:45pm
very true, but we have seen no evidence of this better way............. ------------- |
Posted By: Daniel Holman
Date Posted: 06 Jan 13 at 10:45pm
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No you're not its only me and my sh*tty eyesight.
"Jib headed" as in a mainsail of a sloop rig, rather than a una like the eps. Not a fan of the byte c2 rig. |
Posted By: iGRF
Date Posted: 06 Jan 13 at 10:53pm
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That rig of yours on the Punk, where do you sheet that, I didn't take a note of it, I was to taken up by the methodology although it did appear to be alterable.
Edit. I've checked my pics, yours is centrelined, so you can do it on yours, is that because the rig has more twist tendencies at the head? 
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Posted By: Bootscooter
Date Posted: 06 Jan 13 at 11:10pm
I absolutely *heart* that mainsheet routing system - spent ages drewling over it that year at the dinghy show. I also dont understand why no major manufacturer hasn't done similar on their newer designs!
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Posted By: iGRF
Date Posted: 06 Jan 13 at 11:18pm
| I still haven't worked out why it's not already in production, the whole boat, it carved through every other 'recent' boat design like a knife through butter at the FOM, I mean it wasn't even close at times, nor will he sell it to me. |
Posted By: Bootscooter
Date Posted: 06 Jan 13 at 11:20pm
Let's be honest.... You'd only bugger it up trying to make "improvements".
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Posted By: ex laser
Date Posted: 06 Jan 13 at 11:21pm
proper evidence of a better way. ------------- |
Posted By: Daniel Holman
Date Posted: 06 Jan 13 at 11:27pm
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Sheeted down to deck exclusively. Whole rig and deck geometry was designed around getting all the way out to 14 deg on main ad traveller alone - a necessity with the wishbone, hence mast position, bmax all the way aft etc. Up to 30 kg of leech tension upwind.
9 deg is half way between deck edge and centreline. |
Posted By: Daniel Holman
Date Posted: 06 Jan 13 at 11:31pm
| It never comes in from halfway between centre and the edge (9 deg), all that happens else is you go slow, the foils stop working and make more leeway. The pics were just on the beach before sailing and people may have been messing about with it. |
Posted By: Daniel Holman
Date Posted: 06 Jan 13 at 11:33pm
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It never comes in from halfway between centre and the edge (9 deg), all that happens else is you go slow, the foils stop working and make more leeway. The pics were just on the beach before sailing and people may have been messing about with it.
I won't ever sell that boat, it'd be like you selling your daughter. Bad example perhaps! |
Posted By: tick
Date Posted: 07 Jan 13 at 7:16am
| Swaps?? |
Posted By: GybeFunny
Date Posted: 07 Jan 13 at 7:23am
Does the punk carry much water in the bottom when sailing in light winds, if so doesnt this mean that the mainsheet run is through the water in the bottom of the boat so that the mainsheet will always be wet when you sheet it in as it has just run through water?
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Posted By: Daniel Holman
Date Posted: 07 Jan 13 at 8:29am
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Cockpit never holds water in it. It's not baled so I did my homework thoroughly on that.
That said I've never sailed a boat that had kept a dry mainsheet in anything but a total drift. |
Posted By: Do Different
Date Posted: 07 Jan 13 at 8:42am
| Pointing high is not the same as sailing high. In light air a boat that is "pointing" high will most likely be going very slowly with the foils stalled and actually sailing a much lower course than the direction it is pointing suggests. What is happening under the water is just as important as above. |
Posted By: winging it
Date Posted: 07 Jan 13 at 8:52am
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yes Tick, I use loads of downhaul because I'm overpowered nearly all the time. I just watched a short video clip of me in my last race. The rig is pretty much Finn sized. Graeme, get someone to film you sailing so you can have a really good look at your sail shape, make notes of the changes you make while sailing so you can then compare them with what you see on screen. This is an amazingly useful way of getting to know what your rig is doing and how your controls are affecting your sail shape. Even better, it's exactly suited to your weight because you're the one sailing. ------------- the same, but different... |
Posted By: iGRF
Date Posted: 07 Jan 13 at 9:00am
Very true, but some craft do have the ability to point higher and sail faster than others, but there is of course an optimum, which you'll just have to accept I am aware of after the years of the various types of craft I've campaigned and with varying degrees of success and failure, so I do know some of the reasons for what we're discussing here. But what I still cannot fathom is the absolute reason for this sheeting angle issue on dinghies versus sailboards and so far although there have been lots of very intelligent and helpful answers, I still am not convinced it's anything other than sail design and lack of mast bend and sail twist that's aggravating the situation. Our foils are not really different to your foils (other than the skeg over the rudder which could also be a contributory factor) our foils stall just as your do as do our sails, but we still manage to run them in the same plane, i.e. the attack angle of the sail is similarly aligned with the attack angle of the centreboard foil, that is not the case with my dinghy, so the only difference is, the trailing edge of the top part of our sails is obviously not aligned since it is twisted off, whereas the top part of a dinghy sail is closed and still remains aligned so it therefore must contribute to the stall and that is my best guess as to the reason so far... So it therefore follows if a sail could be built to twist the same way a sailboard sail twists then it should be possible to sheet to the centreline at boom level (where all the power is) and get the progressive twist and exhaust effect up the leech which will continue to provide optimum drive whilst pointing as high as possible. There that about sums it up. Good, glad I've got that cleared up before I start the days work. I'll now have to think of a way to do it with a mast that doesn't bend so much because of the bloody bolt rope.. |
Posted By: iGRF
Date Posted: 07 Jan 13 at 9:03am
Good idea Wing Wang, but easier said than done and I only ever sail to race so pretty much anyone spare is concerning themselves with race organisation and it's a bit embarassing asking someone to film you.. |
Posted By: maxibuddah
Date Posted: 07 Jan 13 at 9:05am
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Back to your point about the kicker grf. On a dinghy it controls the leach tension. Too much and it chokes the flow over the sail, too little and the leach opens destroying your pointing. Very important to get it right. As a general rule of thumb have a tailtale on the leach end of the top batten and when the kicker is at the right tension it needs to be fluttering about 50% of the time. Not flying then loosen the kicker, and flying all the time then tighten it. This is important to retain the pointing on a single hander especially if the sail has a large roach and it's difficult to control the leach. That's why phantoms use more kicker than most.
As for the sheeting its been pretty well said, especially by Dan. But sheeting ain't everything. Also according to that Cockerell bloke some boats will sail to windward by heeling them to windward as you go upwind, but I'm not sure the eps is one of them. ------------- Everything I say is my opinion, honest |
Posted By: Oatsandbeans
Date Posted: 07 Jan 13 at 9:18am
| GRF, if you cant get anybody to photo you from outside your boat get shots from inside your boat. I have rigged up a Gopro on the boom, but it could also be at the foot of the mast. This is directed up to the mast head and will take rig shots for you. At first the shots look a bit weird but they can tell you a lot about your rig, as you change the various controls and importantly how it responds to gusts. Images from the footage can be analysed using freely available software ( best one I have tried is from UK Sails Accumeasure I think its called). This digitises the sail profile at various heights and puts real numbers to those meaningless word of " a bit full", or "flat". Once you have all this data you just have to work out what you want as camber, and camber distrubution and you are away! |
Posted By: RS400atC
Date Posted: 07 Jan 13 at 9:19am
Isn't there an awful lot of friction in this mainsheet? 2 extra 90 degree bends and a near 180. Does it not matter because there is always a fair bit of leech tension? Must admit I'm old enough to have started out with old-tech transom sheeting in things like Ents with wooden booms. We managed OK in them days! |
Posted By: iGRF
Date Posted: 07 Jan 13 at 10:18am
Yes I'm very much of the school of heeling them to leeward in light air, it helps for a couple of reasons, with a flat bottom boat you get to reduce wetted area by engaging all the round bits, the curve helps point you in the right direction and gravity assists the sail to adopt the right shape if there aint really enough wind, it's the same on boards (If pumping isn't permitted). The kicker thing it is true I've never really gotten to grips with it, I get it and get what it does or is supposed to do, but never really had it proved to me and with a rear sheeted boat isn't the sheeting from the rear pulling the boom down doing much the same thing? Bear in mind for the most part I've only ever experienced those gnav things that bend the mast all wrong and flatten the sail where you don't want it flattened. On an old fashioned soft sail rig, yes I can see the kicker needs to function, but with higher aspect full batten sails and rear sheeted? But you could be right I might not have had the kicker working since my focus was on the sheeting angle/or because there was too much kicker the over sheeted nature of centrelining would have accentuated the top of the sail being closed by the kicker. |
Posted By: rb_stretch
Date Posted: 07 Jan 13 at 10:22am
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I think there are several reasons when a windsurfing sail appears to be sheeted on the centreline. I think twist is part of the issue, but the reason windsurfers need so much twist is because their rigs are much closer to the water. The bottom metre of air will be very disturbed wind so for a fast travelling windsurfer you want the rig on the centre line to minimise drag more than you do for power (if you look at most dinghies, the boom will not be less than a metre off the water). The twist needs to happen to ensure that the part of the sail that is actually doing the pulling/pushing does have a sensible angle of attack. Windsurfing rigs are nearly always canted to windward (even if a small amount), but the clew is never on the windward side of the centreline. Although the whole rig appears on the centreline it is actually rotated so the angle of attack is never zero, except for the bottom of the skirt which isn't do much other than giving you the end-plate effect. Finally windsurfers get away with a much smaller angle of attack, because they are so low drag (the planing/foil wetted surface area is tiny in comparison to a dinghy) that they don't need anyway near the power than a dinghy does. Add those together and I think you may have your answer. ------------- |
Posted By: maxibuddah
Date Posted: 07 Jan 13 at 10:56am
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Agree with you about heeling to leeward in light airs grf but I was talking about to windward, so back on top of you. Steve's theory is that the normal Hull shape when upright is symmetrical and fairly neutral. When you heel to windward the hull becomes more wing shaped with the straight edge being the centreline of the Hull and on the leeward side. The curved windward side acts as the top of the wing. This means that at a certain speed it will lift the hull to windward. Apparently it only happens with certain boats with certain foils too. Now not sure if it has been scientifically proven but it sounds possible.
As for the kicker again, yes the main will control leech tension but normally that means it will being the main into the centre which slows the boat. Methods to get over this are a traveller like the finn or to use the kicker and not sheet too far in. Your boat will be the latter. ------------- Everything I say is my opinion, honest |
Posted By: pondmonkey
Date Posted: 07 Jan 13 at 10:57am
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slightly controversial, argumentative post warning... If windsurf rigs are so efficient at sheeting over the centreline, how comes they suck upwind so badly? The angles sailed are atrocious, even the most pointy board (an old Div 2) will still get stuffed by something as pedestrian as a Laser upwind- unless it's blowing its tits off of course, then they sail off the fin which is totally different from displacement sailing being discussed here. Most intermediate windsurfers still suffer from the walk of shame every now and again. You get blown downwind and have to beach somewhere down the coast and walk back pulling your board through the shallows/kite surf central; or worse, walk back, get the car and drive downwind to pack your sh*t up before heading home red faced as the kities laugh at you. The only way you can get any half decent windsurfer upwind is by either: a) get planing, get on the fin and carve it up- not displacement sailing b) practice something Guy Cribb calls 'Look Depressed'... here's the article: http://www.guycribb.com/userfiles/documents/Look%20Depressed.pdf - http://www.guycribb.com/userfiles/documents/Look%20Depressed.pdf Why oh why, would anyone want to take anything from windsurfing and apply it to upwind dinghy sailing? Let's be frank, in the my toy is better than yours p1ssing contest, a dinghy soaks all over the windsurfer and still has enough left to flush away the pubes from standing at the back of the toilet block.
------------- |
Posted By: Daniel Holman
Date Posted: 07 Jan 13 at 11:09am
| Raceboards ie with daggers are rapid upwind in anything. Like seriously rapid. not bad pointing either. When well sailed. Formula kit goes like a stabbed rat upwind once planing, but will rip your face off if you try reaching on it. The recreational shortboard on the whole is specialised to being fun to reach around on. (Sniggers) to get upwind you need a big fin, which in turn needs a big board which then is a ballache in all but flat water and obv is off the cards for wave or freestyle tricks. Hence modest fin sizes which mean that modest upwind progress can be made if sailed well on the plane with plenty of power. |
Posted By: Daniel Holman
Date Posted: 07 Jan 13 at 11:19am
There is a fair bit of friction, which along with the act there are 6 singles and a ratchet on there are te only shortcomings. The friction isn't a major as the correct way to get an unstayed una upwind is to sheet it down and leave it, steer to the telltales and let the rig do the rest of the work. It is still far cheaper and more beach/recreationally friendly than having either a traveller, or the lowers and powerful vang approach, with all the utility of either. |
Posted By: Oatsandbeans
Date Posted: 07 Jan 13 at 11:19am
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Re sheeting angles of singlehanded dinghies compared to boards. The important thing to compare is the angle that the rear section of the sail makes with the course through the water, as this to a large extent defines the angle of the aerodynamic force on the sail. A sailboard will, probably, have a flatter camber, so the sail can be sheeted closer without incurring excessive drag, it will also have a different angle of leeway than a dinghy, just watch your wake when sailing a board and comparing it to the course made good. Often when sailing a board you load up your back foot and really drive off it which increase the angle of attack of the fin dramatically. This will mean that the sail can be sheeted even harder without incurring drag, and it will appear to be on the centreline of the board. A final point to note is that with a board you become very aware of the point that the sail stalls. As you sheet in the load goes up in your back hand, and if you overdo it, the load will drop off dramatically, as the sail stalls, here you will intuitively, ease the sail out to reattach the flow. This means that you will be continually driving the sail to its max. In a dinghy, for most of us, this is not the case, we have no direct and immediate, feedback from the rig to tell us that we have stalled it out by oversheeting, and we can sail along quite happily with a stalled out sail, and only realise when someone sails up and round us that all is not well.
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Posted By: iGRF
Date Posted: 07 Jan 13 at 11:48am
This says it all. As to sailboards, what you ues Jimbo, no disrespect intended here but they are the toy end of the sport, serious race stuff, a guy at our club I race regularly and beat on a sailboard, I've never touched him in a dinghy and nor has anyone else not our Best Laser sailor, he gives our Best Lowind Contender sailor Mental Breakdowns when he covers him (inadvertently he doesn't realise he's doing it he's just overtaking to weather) and that really good Laser Guy also an MPS jockey of some standing, can't take him, so at their state of the art best a Raceboard could only really be matched by a foiling Moth nothing else sat down would be in the same leg of the course for long. So anyway what I'm taking from all this is either start reading telltales better and pay more attention to kicker, but, I still think there is room to mess with the sail. |
Posted By: winging it
Date Posted: 07 Jan 13 at 12:00pm
I'm sorry but that's just not so. Any decent sailor will only have to look at the sail to see it's not working. Once you've got to know your boat you can and do feel how it's going and you notice the subtle changes that occur when you tweak the controls. ------------- the same, but different... |
Posted By: pondmonkey
Date Posted: 07 Jan 13 at 12:05pm
none taken- I totally agree they are beach toys, not racing media. Having seen the Starboard Phantom 380 in Cannock the other week, you'd be forgiven for thinking it was a single hull of a racing cat.... a different beast altogether from the part ex dross from Club Vass in the racks. http://vimeo.com/28839702 - http://vimeo.com/28839702 ------------- |
Posted By: Daniel Holman
Date Posted: 07 Jan 13 at 12:47pm
 Another thing about board sails is that they generally operate at a much lower lift coefficient, which is equivalent to saying that the sail will be working in a state of much more overpower.(lift coefficient is proportional to side force / (apparent wind strength squared x area) I.e. a guy hiking out in a dinghy will be putting significantly more righting moment and hence side force on a 8m2 sail than a guy holding onto a an 8m2 rig on a board, even if wide. The board will be going at least twice the speed, hence the speed squared term will be much higher. This means that the board sail will need to be flkatter, more twisted, and with much more skin tension. Direct sheeting means that the quick response necessary with such flatness is possible. Until its really windy, an unstayed dinghy will go upwind best with reasonable fullness all the way up the rig and minimal twist, with the aforementioned sheeting angles. |
Posted By: iGRF
Date Posted: 07 Jan 13 at 5:26pm
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That is such a nice sail particularly for those conditions. Not sure I entirely agree with your calculations, sure when breezy boards move quite fast but in sub 8 knots they're (Raceboards) moving at displacement Speeds and we're hanging onto 9.5 sq mtr rags not unlike that one, although in my case a little lighter weight perhaps but with just as much stand out at the head if I'm not running much downhaul.
And I note how close to the centreline that rig is hence it sailing higher and faster than mine imv. |
Posted By: Daniel Holman
Date Posted: 07 Jan 13 at 5:37pm
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It's still not quite there, but good enough. May not look it but that is set at 9deg off centreline there - halfway between centre and edge.
Obv in 15kts the down haul starts coming on which flattens a fair bit esp at head and puts a lot of twist in. What you up to Saturday Graeme? |
Posted By: Daniel Holman
Date Posted: 07 Jan 13 at 5:39pm
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The point re lift coefficient is that there is only so much force / leverage that a little fella can derive from a sail when his feet are near the centre line.
Race board sails are halfway between rec free ride sails and dinghy sails I'd say. Can be firmed up for the light air work. It's still a very different ball game though. |
Posted By: iGRF
Date Posted: 07 Jan 13 at 6:16pm
Depends, if the cloth arrives and my new sail gets cobbled together and the weather looks do able then I might do a last minute dot com Bloody Mary.. |
Posted By: iGRF
Date Posted: 07 Jan 13 at 6:26pm
| Raceboard sails, depends who makes them and there are only two or three folk left who know how to do it. |
Posted By: Chris 249
Date Posted: 07 Jan 13 at 11:45pm
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Some interesting posts, chaps.
Re "even the most pointy board (an old Div 2) will still get stuffed by something as pedestrian as a Laser upwind". Sorry, no way do all boards suck upwind. I did a fair few races or trials between Canoes, lowrider Moths (Hungry Tigers), Lechner Div 2 and Mistral and other Raceboards, plus raced in or shared a course with the Raceboard fleet for years.
The Canoe and Moth were out-performed upwind from about 6 to 8 knots by the boards. The boards may have been a degree or two lower, but their VMG advantage was such that they could have been pinched to the same height and still probably have been at least as quick.
All of those involved in each class (apart from when there were actual fleets) had finished at least top 3 in that class nationally and the Mothies were 1 and 2 in the world at the time, so the standard of sailing was reasonable.
Some times the boats will kill the boards but in my experience that's when sailing in light and shifty stuff (where the boards lose in tacking) or in light winds funnelling out of a bay, where the boat's slight pointing advantage will allow it to hook into the lifts and the board's footing will just put it out of the shifts. The boards can normally stuff it to hang as high as a Laser etc but they don't because they get better VMG lower and faster.
FWIW I don't believe that windsurfer rigs are actually "better"; as others have mentioned, they just benefit from being able to be optimised to drive a very low drag hull, and the ones designed mainly for reaching are terrible upwind. A few years back the biggest UK windsurfing event saw 2nd out of about 300 in the "Sport" class go to an original Windsurfer with dacron "pinhead" sail and down here we have seen similar destruction of modern "funboard" fleets by original Windsurfers in some races - for all the furore the modern non-racing boards and rigs are incredibly slow at times.
Modern board rigs also suffer from being very heavy - they claim to be light and efficient but the original Windsurfer sail (6m and around 2.1 kg) is half the weight of a current sail, or less. Fine if you are thrashing through waves or freestyle (when strength is vital) or blasting in steady winds, but a pain around the light and fluky winds of many dinghy courses.
It's not one being more advanced than the other, just different approaches created by different requirements and driven by different dimensions.
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