Topic : The cut of your jib...

Hi all, what are the benefits of a Fat head jib over a standard cut jib? Tackled behind the chute. Does it make a difference? Look forward to your response.  Cheers.

Posted: 26/01/2020 07:58:57

I bought a North fat head jib and really like the way it twists off in gusts and with a crack of the sheet. 

Really happy with it and have bought two since

Posted: 28/01/2020 09:16:22
By: Gareth Griffiths
The idea of the fat head jibs is that there is greater reistance on the leach so that when a wind increase hits the head of the jib, it twists open slightly and the closes back when pressure eqaulised so maximising constant flow (Bernoulli's Theorem of fluid dynamics). They first appeared on the P&B jib in I believe 2007 when we used a development one for the Merlin Nationals in Liquid Dreams. They are now on most jibs and would not consider a jib without one if allowed. We are now running the latest North Sails fat head option as launched late 2019 on Dancing Brave.

Posted: 28/01/2020 11:21:23
By: Barnsie
And a cracking sail they are too mate

Posted: 28/01/2020 21:42:52
By: Gareth Griffiths NHRC
It's not Bernoulli's theorem (it has some context but not this).
Fat head were bought in as a way to reduce luff  length but keep sail wars as calculated in IRC and other fleets including Merlin's. (LL xLP )/2
thereby allowing more area on mainsails etc.
The by product of them is that too a certain extent they are aerodynamically better this is more due to leech position though.
A common problem with them when first made (and a reason for the now illegal jib bar  head fitting) was that it was hard to stop the leech falling away was the sheet control runs pretty much in a straight line from clew to head point.

Posted: 28/01/2020 22:33:12
By: Dave
Interesting points Dave. 

Guess that points to why athwartship jib cars are becoming a topic for change..

Increase Slot ?

Posted: 30/01/2020 08:18:45
By: Gareth Griffiths NHRC


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