Foil lift / tracking
Printed From: Yachts and Yachting Online
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=10710
Printed Date: 13 Dec 25 at 2:58am
Software Version: Web Wiz Forums 9.665y - http://www.webwizforums.com
Topic: Foil lift / tracking
Posted By: pondmonkey
Subject: Foil lift / tracking
Date Posted: 14 Feb 13 at 6:16pm
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I've done it before with other boats, notably the RS100 when the stars aligned once and against all odds I nuked a 300 to the windward mark once, but I found last Sunday that upwind when the boat just 'felt right', I seemed to go through a phase of pointing lower than others, but then started tracking to windward despite the angle I was pointing.
It was devastingly effectively at clawing back a 20 boat length gap after missing the start, I'd just like to know how to do that on demand, rather than rely on some celestial passing. Any ideas? |
Replies:
Posted By: tgruitt
Date Posted: 14 Feb 13 at 6:18pm
I thought that is how you are supposed to point well? That's what I've always done, drive off hard and get the boat up to speed and will keep nice and high. ------------- Needs to sail more... |
Posted By: getafix
Date Posted: 15 Feb 13 at 6:45am
| A long time sailing friend and nemesis used to talk about 'making the foils work' ... it took me some time to work out what the heck was being referred to, but yes, if you focus you can do it and what really struck me was the wind range it works across, it's not just for when it's breezy |
Posted By: Oatsandbeans
Date Posted: 15 Feb 13 at 7:26am
| I am a little bit suspiciuos of some wonderful effect where the foils all of a sudden start to generate extra lift and dramatically improve the Vmg. I suspect that when incidences occur where the boat suddenly goes into warp speed and sails up and around the competition the effect probably lies in the sail setting. Sometimes sailors can get end up " parked-up" on the race course with their sails stalled and little forward speed, and sometimes as one does this the boats close by endup in the same state as they try to copy the angles and sheeting of the first boat. If you then come along with all your sails set correctly and good flow on the foils you can sail up to and around the poor bunch and off into the distance. |
Posted By: rb_stretch
Date Posted: 15 Feb 13 at 7:43am
| The foil effect was even more exaggerated in windsurfers particularly in the period late 80s to mid 90s when fins were rarely above 35cm long. I reckon you probably needed well over 10knots of boat speed before you could even consider going upwind. |
Posted By: maxibuddah
Date Posted: 15 Feb 13 at 7:47am
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According the Cockerell bloke its to so with heeling slightly to windward while pointing about right and at a certain boat speed with a certain foil and Hull shape then the boat will track to windward. I did it once in a laser. Unfortunately I didn't realise that was what did it so didn't try again.
I believe the theory is more to do with the shape of the hull through the water but the foil is still important. When heeling to windward the centreline of the boat is the leeward edge baking contact with the water and is straight. The windward side is curved. This produces a flow similar to an aeroplane wing causing lift to the windward side. However it only seems to work with certain foil/Hull shape combinations. ------------- Everything I say is my opinion, honest |
Posted By: pondmonkey
Date Posted: 15 Feb 13 at 9:02am
I'm not sure this is the same, I've certainly carved upwind on the fin of windsurf boards many a time, but this felt totally different. It was as if there was a tractor beam (albeit a very lame, but noticeable one) slowly drawing me to windward.... I'd love to know how to do it again. It was relatively windy, no tide, slight reservoir chop but nothing to unsettle the boat. I was relatively powered up and thought I had the boat flattish and nicely trimed fore/aft... upwind speed, in a Solo... hmm, no GPS, but guessing maybe 6 knots through the water??? ------------- |
Posted By: Daniel Holman
Date Posted: 15 Feb 13 at 9:21am
Ha ha ha ha ha 6 knots upwind in a solo!!! Thats the best laugh I've had in a long time! You'll win every race at the worlds by 3 minutes! |
Posted By: pondmonkey
Date Posted: 15 Feb 13 at 10:02am
right... I'm off the Bristol channel on a spring ebb armed with my heinously out of class GPS device.... I will spike 6 knots and prove you wrong one day Holman! ------------- |
Posted By: G.R.F.
Date Posted: 15 Feb 13 at 10:19am
I bet it did more than 6 knots upwind on that back of that low loader, where you should have left it... ------------- https://www.ease-distribution.com/" rel="nofollow - https://www.ease-distribution.com/ |
Posted By: Steve411
Date Posted: 15 Feb 13 at 10:31am
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I think 6 knots may be a bit on the high side, perhaps 5? Fully powered up and hiked I get 6 to 6.5 knots upwind in the 300 (according to the GPS). However, this speed doesn't increase much as the wind increases, though possibly does a bit in a Solo??
Windward heel can be devastating upwind in a 300 as maxi says. ------------- Steve B RS300 411 https://www.facebook.com/groups/55859303803" rel="nofollow - RS300 page |
Posted By: sargesail
Date Posted: 15 Feb 13 at 10:38am
| Steve - remember that winters at BCYC when it was just you and me doing it? Good days! |
Posted By: pondmonkey
Date Posted: 15 Feb 13 at 10:42am
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oi oi... no 300 love-in thanks Matt... salt into the wounds n' all that. OKay so six knots optimistic... I'll have to take a GPS out a recalibrate my perceptions. Of course I will retire from any club results I achieve as I will be technically out of class by carrying it ;-) ------------- |
Posted By: SoggyBadger
Date Posted: 15 Feb 13 at 11:21am
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A Solo for all its charms cannot plane upwind. To achieve a displacement sailing speed of 6 knots it would need to have a waterline length of at least 20 feet. In reality its maximum displacement speed is going to be in the region of 4.5 knots.
------------- Best wishes from deep in the woods SB |
Posted By: pondmonkey
Date Posted: 15 Feb 13 at 11:34am
thanks... as I said it was guess, what I'm interested in doing is replicating the feeling of being sucked to windward.... there's a friday afternoon gag for Mr Holman there too, oops, and another one. ------------- |
Posted By: Daniel Holman
Date Posted: 15 Feb 13 at 12:12pm
Just bear off to 85 deg TWA and you might coax 6 knots out whilsts still technically achieving some upwind progress. I would bet that you like to "reach around" |
Posted By: Daniel Holman
Date Posted: 15 Feb 13 at 12:15pm
Steve is a good orator but questionable physicist/engineer. By definition a boat without a gybing board or trim tab must make leeway in order to generate sideforce to counter righting moment. There are a lot of boats for which ww heel is good in the right circumstances, in a few ways enhancing the efficiency of the foils. This means that the boat may achieve the same sideforce (countering the same righting moment) at a slightly lower leeway angle, meaning less induced drag and seeming to climb up on other boats. |
Posted By: pondmonkey
Date Posted: 15 Feb 13 at 12:16pm
in a pink solo, it would be rude not to... 'god damn common courtesy' according to my drill sergeant. ------------- |
Posted By: Daniel Holman
Date Posted: 15 Feb 13 at 12:18pm
?????? Cue lilting guitar music... Summer turned to autumn, ah thought ah'd never see him agin. Then one day I was stroking the steer in the yard an there he was, sunlight glinting on his mus - tache. Ah grabbed him by the waistcoat an we musta rolled around in the mud for good 2 hours. Ah gripped him tight to me an said to him: "Don't you ever leave me boy!" |
Posted By: Steve411
Date Posted: 15 Feb 13 at 3:06pm
You were there?  ------------- Steve B RS300 411 https://www.facebook.com/groups/55859303803" rel="nofollow - RS300 page |
Posted By: pondmonkey
Date Posted: 15 Feb 13 at 3:45pm
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the serial brokeback dogger ol' Holman is.... ------------- |
Posted By: tgruitt
Date Posted: 15 Feb 13 at 3:57pm
You attract a mate with interior light on and passenger window a few inches down isn't it? ------------- Needs to sail more... |
Posted By: pondmonkey
Date Posted: 15 Feb 13 at 4:44pm
I dunno, I could chat with Severn Trent... they had a spate of chasing doggers off site after hours a while ago. Well that was the official line, I've also heard it was kite surfers breaking inland use rules (doggers being more socially acceptable trespassers softened the story and kept the Rugby Chapter of the Daily Wail Readers Association from investigating) ------------- |
Posted By: pondmonkey
Date Posted: 15 Feb 13 at 4:46pm
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Anyway it appears that it wasn't so much I was making ground to windward, but just not losing to leeward... hence the perception of windward climb. Interesting... mind playing tricks I guess... either that, or it was a tidal lee bow ------------- |
Posted By: maxibuddah
Date Posted: 15 Feb 13 at 5:23pm
No it was a miracle, I mean getting a solo to go fast enough to overtake someone???  ------------- Everything I say is my opinion, honest |
Posted By: pondmonkey
Date Posted: 15 Feb 13 at 5:45pm
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It was another Solo Maxi... really, why would I choose a solo if it weren't for the other folks sailing them? ------------- |
Posted By: G.R.F.
Date Posted: 15 Feb 13 at 8:07pm
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Why am I not surprised that some folk on here know how to initiate a 'dogging' session. ------------- https://www.ease-distribution.com/" rel="nofollow - https://www.ease-distribution.com/ |
Posted By: maxibuddah
Date Posted: 15 Feb 13 at 9:43pm
Insanity? ------------- Everything I say is my opinion, honest |
Posted By: tick
Date Posted: 15 Feb 13 at 11:26pm
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I wish you would leave the poor old Solo alone, How else would we deliver coal? |
Posted By: maxibuddah
Date Posted: 16 Feb 13 at 10:55am
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Very good boat for what it's intended use is. Lots of people spent a lot of hours enjoying their sailing in them, which is what it's all about ------------- Everything I say is my opinion, honest |
Posted By: tgruitt
Date Posted: 16 Feb 13 at 12:11pm
As if you don't? I see you've just sold your doggingmobile! ------------- Needs to sail more... |