foiling 18

Discussion in 'Sailboats' started by John ilett, Aug 31, 2006.

  1. casavecchia
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    casavecchia Senior Member

    What was the speed at takeoff?
  2. jpz
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    jpz Junior Member

  3. Doug Lord

    Doug Lord Guest

    Great work jpz! When you get a chance,what are the main, jib and gennaker sail areas and the total all up weight MINUS crew?
    EDIT: jpz, I answered the questions by going to the website. While searching, I found that hydrofoils are specifically banned by the UK 18 footer Class Rules but don't appear to be banned in the European class-is that right? And is the boat on foils using rig one or two?
    For those interested in a more technical analysis
    here is some interesting info:
    Euro 18 Sail Area:
    _____ Rig One | Rig Two
    Main 257.59 sq.ft. | 208.09 sq. ft.
    Jib 98.02 | 75.32
    Gen 794 | 664
    Total Sail Area
    upwind 355.6 | 283.41
    all up 1149 | 947
    "wing" Loading(In the Moth class a wing loading under 2.58 appears necessary to foil competitively upwind.)
    Moth with Rohan aboard 2.37 lb.per sq.ft.SA
    18 Rig One Rig Two
    upwind 2.4 | 3.01
    downwind .74(!) | .9(!)
    A)--FOIL AREA/FOIL LOADING:Mainfoil loading calculated at 80% of all up weight.
    1) Moth with Rohan aboard(very light): 156.9lb per sq.ft
    2) 18 weight(854) X .8 = 683 Divided by the Moth foil loading = 4.35 sq.ft.=approx. mainfoil area of 18 at same foil loading as a Moth.
    B)-SA per sq.ft. Foil Area(mainfoil) :
    Moth: approx. 82.6
    18 Rig One Rig Two
    upwind 81.7 | 65.15
    downwind 264(!!) | 217(!!)
    Well, thats very interesting. From this comparison the 18 should be able to take off in the same conditions a Moth does with it's #1 upwind rig. And more than that it should be able to sail upwind in fairly light air. The only possible negative might be a less efficient upwind rig than a Moth has. Off the wind in light air this thing should set records(esp. in boat speed multiples of wind speed)-- it will be real interesting whether or not the boat is faster than a conventional 18 in a strong breeze and also whether it sails faster than the effectiveness of the gennaker.
    Congratulations to everyone invovled -this is surely an exciting development! Good Luck-and when you can release actual foil areas some of us would be real interested!
    Last edited by a moderator: Sep 8, 2006
  4. pchanez
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    pchanez New Member

    Hello Doug,

    The European Class rules allow them for sure. The current version of the australian rules as well. There are limitations in both of them but it was to avoid foils under the wings. The UK is sailing under the aussie rules, so at the moment there is no restriction about using foils on center board and rudder

    I know that the Aussie are in the way to change the rules and they will probably ban this ... but at the end, they will follow the day they willl come in Europe and see the other flying, I'm sure. This is what happened with many things in the past

    One thing is now sure, I will foil my boat during the winter and I know already 2 other teams who are ready to do it

    Secretary of the European 18' Class
  5. frosh
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    frosh Senior Member

    I hpoe that the originator country, Australia, has the sense to ban this new development as something that adds considerable complexity, cost, and will lead to more disastrous wipeouts than before. The 18's are challenging, fast enough, and a great spectacle the way they were.
  6. Baronvonrort
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    Baronvonrort Junior Member

    I would have to say John Ilet appears to be a doer rather than a typer and well done in getting the 18 on foils.

    When did hydrofoils become legal in 18ft skiffs as my memory recalls they have been banned for quite some time?

    The photo also suggests the wings may be a little wider than legal and i always believed 14ft was too narrow and 17-18ft span is closer to optimal and i have sailed with 22ft span back in the 1980's.The Grand Prix sailing 18's were about 20 minutes quicker around the course with their 17 ft span compared to the current one design 18's.

    There has always been a rebel spirit with the 18ft skiff sailors so good luck with what you are doing and can we have some more photos.

    Flipper has had his 18ft skiff foiling so it has been done before.
  7. RHough
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    RHough Retro Dude

    Why would anyone want to ban foils on 18's?

    Did I miss the news flash that a foiling 18 was faster than a non-foiling 18?

    Has anyone done any towing tests to see if a foiler has lower drag than a planing skiff at the same speeds?

    It doesn't look like this boat has much extra wetted surface to slow it down ...

  8. pchanez
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    pchanez New Member

    You're nearly right Baronvonrort. When the rules were written, the class decided to ban hydrofoils under wings, that was tried by Emett Lazisch if I'm not wrong. But at this stage nobody thought that having T-Foil on rudder and centerboard would be possible. It is why it is in the rule at the moment. The rules said :

    "There should be no hydrofoils except centerboard, rudder and hull"

    For Thomas wing, you are also right. Thomas has some "rack extension" to extend the wings to a GP size. He's using this when he's sailing with a special Lake rig (wing mast of 11m heigh) and on the video/pictures they are cliped on.
  9. Doug Lord

    Doug Lord Guest

    The "Baron" is dead wrong when he says this has been done before-complete BS! Thomas' boat with the two foil system is an historic development in sailing-NEVER before has an 18 or any other three person boat sailed on just two foils.
  10. John ilett
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    John ilett Senior Member

    And then two seconds later the planning 18 will have 5-6m or more area in the water. This slows the boat down a bit.

    I imagine that the 18 foiler is likely faster in the lower wind range. 14 knots boat speed in 7 knots of wind must be pretty good??
  11. RHough
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    RHough Retro Dude

    I don't think foils should be banned at all. The 18's (In my mind) have always been about few rules and going fast. If foils make them faster, I'm all for it! Adding foils will most certainly add less cost than the hydraulics etc. that the boats had before they changed the rules.

    2xwind speed in 7 knots of breeze is damn impressive number!

    Well done.
  12. Baronvonrort
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    Baronvonrort Junior Member

    Your interpretation of the rule banning hydrofoils is going to be challenged if you try to race with those lifting hydrofoils.The spirit of the rule was to prevent those with budgets exceeding $250,000 pa from going down that path.The 12ft skiffs recently had some youngster interpret the rule the same way as you have and they added the word "lifting" as a prefix to hydrofoils and that removed any confusion to whether they are legal.

    The NSW 18ft skiff club was behind the push for the one design 18ft skiff and from my experience with them they are unlikely to allow your hydrofoils to compete.

    I have never liked the current rules so i like what you are doing and i am letting you know it will cause some controversy.I cant recall Emmet Lazich trying foils and Flipper is Michael Carter and he has foiled with his 18ft skiff.

    I hope you are playing this game with sponsorship dollars and not your own money.

    How much do you think that 18 in the photo will slow down in 2 seconds as you put it when another 5-6m of the boat is in the water?

    My experience from a couple of decades sailing 18's is they do not suddenly accelerate because they become airborne and they do not slow noticably when coming down unless you nosedive.Upwind they are pretty impressive in choppy water.

    Frank Bethwaite published a few articles in early 1983 and they are on his website along with polars of 18' ft skiffs in various conditions.23 years ago 18ft skiffs could do 16mph in 8-10 mph wind.

    Do you back Dougs claims that your moths could do an 18ft skiff as he claims the moth can do anything under 20ft?
  13. Doug Lord

    Doug Lord Guest


    Baron, I've almost never said that a Moth foiler is faster than anything under 20'. I almost always say"probably", "nearly" or "almost" the fastest dinghy under 20'. If , at any time, I did say that the foiler Moth was faster than any boat under 20' I was surely, and probably temporarily, wrong. It is faster than an A class cat, an F18, a IC, a 49er and many other boats. As far as I know an Aussie 18 skiff has not yet been a victim.
  14. pchanez
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    pchanez New Member

    Baronvonrort, if you read my first post, you will see that I'm telling that the Australian League is going to ban explicitly any T-Foils in the next release of the rules.

    The European rules are more open. We are not one design but we have way to control the cost (we license a boat at a certain price, each license is voted by the whole class, ...). My view on these foils is that this will end the war between B18 and Murray, give a new life to older hull ... At the end of the day, foiling an 18' is not much expensive than all the latest changes imposted by the league (carbon rack, mast, ...).

    But I'm agree that the current rules could be subject to discussion.

    Some numbers I got from Thomas about the trial on the picture

    wind speed : 6-7 knots
    avg speed : 13 knots
    max speed : 14.5 knots
    TWA : 130 degree

    take off at 8-9 knots

  15. Jundt
    Joined: Sep 2006
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    Jundt Owner foiling 18 AET

    Doug Lord
    Your text is interesting and I would like to answer to it.

    May I introduce myself : Thomas Jundt from Geneva, owner of the flying 18 AET

    Rome wasn't build in one day, we need time and practice to discover our machine, but :
    Today I am very optimist about performance (fabulous job of John), I believe on the basis of our 3 sails with foils, that our boat in the hands of an trained team will beat all existing 18s around the track if :
    - Wind more than 2 Bf, say more than 7 kns.
    - No spinakker but a flat unstayed headsail (in cuben fiber) as the one you can see on the photos (apparent wind ) 30 sqm instead 60 as the are the JJ assymetrics now.

    Foiling upwind :
    I think to foil upwind we need 4 Bf of wind in order to achieve the 8 to 9 kn of boatspeed to take off, once out of the water + 2 kn so no question who is faster.
    But even in 3 Bf I believe that the lift of the foils reduces the hull drag sufficiently enough to compensate for foil drag, at he worst the same as none foiling.
    And rudder lift allows to push the bow down, what a traditional 18 tries by moving all weight ahead as far as possible.

    Foiling downwind :
    No question as soon as airborn faster than non foiler
    And I believe no pitchpoling any more (as GP -covers in the pictures of seahorse) when you bear off at the weather mark

    Conclusions :
    - A conversion 18 will be faster than a non foiler 18 (in more than 2 Bf)
    - A 18 foiler build from scrach even more of corse (in all conditions)
    - In any case the lighter the better the faster
    - 18 s are spectacular boats, foling18 s even more
    - The league is fine but it 's become a one design class racing, with low devellopement
    - All the major devellopement jumps (assymetrics, wings, fiber mast tops, carbone masts, etc) weren't made by the league.
    - The price of devellopement is that things become obsolete over night (as typing machines f.i., can you rember the time before PC s ?)

    Classs rules or not, in a couple of years we will see completely different hulls apear (more skiff type, narrow, non planing hulls, (you don't plane you fly) so performance gain will be in light wind and in havy wind.

    .. once you have foiled you cannot go back !!
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