Hinged centerboard

[Jimbo41]

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!)

[JohnMurrell]

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!

[Jimbo41]

[rick perkins]

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?

[Antony]

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

[Phil Brown]

[rick perkins]

[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.

[Phil Brown]

Obviously transomless sailing is OK  (huh2)

[John Meadowcroft]

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.

[Jimbo41]

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.

[THG]

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

[Jimbo41]

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.  

Jim.

[THG]

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

[Jimbo41]

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.

[THG]

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