I read an article in an old Ratchet on the website about a centerboard that had a hinge in it ...
Are hinges allowed in the centerboard still?
Rick
Rick,
Do you have a set of Class Rules? If so Rule no 7 explains all.
Thing to remember with a Twelve Class Rule is that it tells you perameters to work within and what isn't allowed, not what is allowed - also download a copy of the measurers guide from the homepage and that will explain what is measured and how.
If in doubt a call to your nearest or friendly class measurer will also help (pages 4 & 5 in the Class yearbook. I am amazed by the number of calls I get - even from the classes outpost in Bavaria!
However not to be obtuse, the answer to your question is yes - if you can get one to work!
Thanks John ....
Can the hinge be in any plane/angle?
Rick
Rick, basically providing you can get it back into the c/board case go with what you want. Simon Hinks was playing with allsorts of ideas a couple of years ago on 3396, all of which can to nought because the engineering he was coming up with was too complicated and very heavy.................................
Rick,
Does this have the same effect as a hatchet centreboard - improving the angle made by the foil relative to the water plane, so that when it's up it stays near enough the same angle/position to when it's fully down?
Sorry to be so obtuse - feeling a little unhinged at the mo :-/
Oh and in which Ratchet? I spent 2 hours the other day trying to find it...
Cheers!
Jim.
http://www.national12.org/private/Newsletter/Annual%20Newsletter/2002/newsletter.pdf
See page 31.
Thanks Rick!
Jim
Jim unhinged.......... well, perish the thought..... ;D By the way Jim, how come you couldn't find time to write your article for me in Ratchet but could for Mr Wilkins in his offering!!!!
Jim,
Interesting, over the weekend I was trying to find some history of 2632 looking through some of the classes old newsletters, and in No38 of summer 1980 a chap by the name of Dave Peacock (!) wrote an article outlining how a c/board can be made to work like a d/board. The then rules allowed it, however the loophole was closed rather quickly if I remember correctly with the words ' the pivot point shall be in one fixed position related to both the hull and the centreboard' added at the next AGM!
Lots of other juicy bits from the past too including the Dave Eberlin pic of John Royce and Barbara Whyte sailing Tiger Lil at Trent Valley with a big rig, spinnaker, trapeze .................................
[quote by=John_Murrell link=Blah.cgi?b=Cool1,m=1169854006,s=9 date=1170182170]looking through some of the classes old newsletters, and in No38 of summer 1980 a chap by the name of Dave Peacock (!) wrote an article outlining how a c/board can be made to work like a d/board. The then rules allowed it, however the loophole was closed rather quickly if I remember correctly with the words ' the pivot point shall be in one fixed position related to both the hull and the centreboard' added at the next AGM!
[/quote]
When the rules are changed to remove a "loophole" is it applied retrospectivly or can those who innovated the item keep it?
Depends on the rule thats been revised - if its something fundamental to the construction of the boats you get a dispensation which is added to the certificate - I have one on 3003 in relation to the daggerboard. Also if its something like the new sail rules, obviously keep using the old ones with those measurements and its only when the motor needs a rebuild you change to the new rules.
Same works when we have reduced weight in the past, you can keep your boat at the old weight if you want, but if you remove any weight you have to get it reweighed. Thinking about it, Measurers should be in favour of a graduated plan of weight reduction, say half a kilo a year, that way they will always kept in beer tokens for the season for at least the next 20 years ...............................
And I thought it was just the Jammy Dodger who was out to get me! I'll be getting a complex soon!
Cheers
Steve,
My Newbyness might have casued me to have missed something here, but I thought that the pivot point related only to the movement of the centreboard into and out of the case, not to other parts of the centreboard moving relative to themselves. In principle the pivot point remains stationary, relative to the hull and the top of the centreboard. If that's not the case, then surely gybing centreboards would also have to be banned - clearly they are not. In this case, the whole board moves laterally relative to the pivot point.
Cheers!
Jim. (It's ok. Mr. Wilkins - we only want to burn you off good and proper at BW!)
Jim, I stand to be corrected, but I believe a gybing board is allowed because the pin is fixed in one place in the boat and the board moves in its different planes around that fixed point, the concept that Dave P had still kept the pin in one place but had a track fitted to the case that the board was fixed to and moved abouthence in reality there were two pivot points if you get my drift.
The whole ideas of the c/board vs d/board from the '70 showed how people like Jo Richards, Nigel Waller, Rob Peebles Dave Peacock et al were looking at the rules and seeing how they could be circumvented to gain that little extra advantage, in the same way as F1 cars do today with their flexiwings etc.
From what I understand the Friday night pub sessions in Nottingham were a hotbed of beer swilling, totty chasing and Twelve designing!
Could you have a centerboard that had a pivot/hinge that changed it's profile and the whole lot being raised & lowered around a single pivot point in the boat as required by rule 7?
Rick,
Something like that has been done before. Pretty tough to make it work and weigh a sensible amount, as the last pioneer found.
Antony
[quote by=Phil_Brown link=Blah.cgi?b=Cool1,m=1169854006,s=20 date=1175769497]
I am not pro daggerboard at all and don't want to reopen that debate. The reasons for banning them are sound and I understand, and agree with, the principle objection in the past around general damage from going aground and that moment in shallow water, [/quote]
... but you can rip your transom off with a fixed rudder :-/
I was more thinking of a hinged section of the centerboard that would displace water from the case .... giving one of the other benefits of the daggerboard.
Obviously transomless sailing is OK (huh2)
There is no substantial advantage in a fixed rudder over a lifting rudder. It is a matter of preference, but the physics are that the rudder is in the same place. People will no doubt have a preference but it is not a critical choice provided that you get the rudder at the angle that you want.
There is an advantage in a daggerboard over a centreboard as explained below. The disadvantage relates to the nightmare when it all goes wrong. The transom is easier to fix than the daggerboard case.
I am told that daggerboards are easier and cheaper to build than centreboards.
As per another thread the consensus is that the first national 12 had a centreboard and a fixed rudder. We were not sure where the first lifting rudder came from.
After having seen John Murrell gloating over his (now DB) bouncer a couple of weekends ago I am somewhat at a loss to understand why so many of the one-design boats specify daggerboards and yet we are not permitted to use them in our new designs. Even my Mirror 14114 from 197_ (gulp!) has one and it is very easy to pull up and down. If the daggerboard had a safety release system (eg. strong laggy band) then perhaps the force tending to destroy daggerboard casing (mainly horizontal) might be translatable to a vertical one, (reinforced casing) causing destruction of laggy band or whatever, but saving hull. Just a thought and not wanting to put salt on old wounds, but I thought I'd put that "to the electrons" anyway.
Cheers!
Jim.
For those that may not know the Bouncer John M has is one of the few built with a daggerboard before they woz banned.
We have been through this before - check the thread 'Old Chestnut - Rotating DBs'.
Kean
Oi Kean,
you've not read the bit about the elastic band..... I prefer that to a rotation of my DB hull. We're not yet come full circle. Plus the fact that since you and I were probably still just learning to add up whilst the debate woz raging around the ol' boiz an' gurlz ears, I find your last remark just a tad trite. :D
Jim.
Sorry Jimbo - poor choice of words - I meant there was another discussion in the past and the threads are linked.
Is it worth somemone summarising the various options on boards and imapct on new build costs and any rework to existing boats (typical costs/ time) - is this what the technical committee do??
Kean
No probs Kean - we were probably talking at cross-purposes.
The thought of daggerboards still makes me itch though.... What about you Yoda Murrell?
Jim.
Now that there's various types of foam densities around - could we not allow owners to convert their CB slot to a DB slot by filling inthe gap behind with a suitable piece of foam - would this be strong enough to normally allow a DB type function (up and down) but in the event of a heavy enough crash it would deform back and protect the casing too?
Is this too simple a solution? Could the existing CBs be re-worked to be a DB so the the costs are reduced? Not sure what you do for new build though as they could have an advantage with a pure DB type slot.
Kean
But have you actually seen the damage that can happen when a Twelve bears off mark rounding in a bit of a blow, the crew can't get the board up due to the pressue ,the helm loses it and the boat hits the beach flat out? I hava and the result is the board 6 inches back through solid mahagony and Linton spending 3 months scratching his head working out how to mend it; sure foam might slow the destruction process down a bit but I think the boat bodgers would be kept in beer and crisps for quite a while...............
Possibly we need to talk to Bernie Ecclestone and borrow the FIA crash test rig and do some trials - anyone fance lending their boat for a couple of months? Can't promise its condition on return though!!!!!!!!!!!!!!!!!!!!!
I did not know anyone had ever made a plate with a hinge IN IT.
The rules say a plate must pivot about a single fixed point.
This is because during the dagger-board "debate" a structure was put together that allowed a centre-board to be fitted to a pair of vertical tracks either side of the plate case, thus still complying with the pivoting requirement, but behaving like a daggerboard.
As has already been posted there is also a precedent off an offset pivot or hatchet arrangement where the pivot is as low and as far forward as possible in the boat in order to minimise the required length of the plate case and the carried water. In extreme cases this involved a pair of fabricated arms that passed either side of the mast.
Dave Peacock was at the origin of most of these bits of whacky engineering.
I do not think there is anything to stop you putting trim tabs or foils on you plate if you can get them stowed to allow the plate to house.
Mr Fatman 3135 was an experimental boat that I bought from Rob Peebles originally designed to be fitted with a pivoted dagger board box.
Essentially, this was a "signal arm" that I had made of a stainless steel box for the dagger board to move through up and down and this box was attached to a lever which connected to a pin. Visually, think of an axe with the head being the dagger box and the bottom of the wooden handle being the pivot point. The board would move up and down through the axe head. The pivot point was low down.
The board could act as a traditional centreboard rotating up and down, or when the box mechanism was left down the wooden board could be retracted up and down when down wind moving the board point forward.
Main issues were the board was a loose fit in the box and you still had the water in the centreboard slot. The mechanism also cut the crew and helm to bits!
Unfortunately, I moved abroad before I could perfect the mechanism. The centreboard was subsequently replaced by a traditional board by the new owner.
I am not sure if it would be legal now.