Stability

[Old Forum]

Ben Fraser
Username: Ben_fraser

Registered: 10-2008
   
Posted on Saturday, October 25, 2008 - 10:08 am:      
Does anyone have any information on the stability and heeling angles of a winklebrig, particularly what the angle of vanishing stability is? Either officially or through personal experience!?

[Old Forum]

David Cawston
Username: David_cawston

Registered: 03-2007
   
Posted on Saturday, October 25, 2008 - 08:11 pm:      
Vanishing stability, what is that? Is it something to do with heeling over beyond the point of no return? All I can say is that on the odd occasion we have been 'caught out' by a very strong gust, the bulwark next to the companionway has gone fully under water. But apart from stuff in the cabin moving about, Markie has always rounded up nice and safe with only a little water coming inboard. I am convinced the gaff rig is inherently safe and so much wind is spilt when heeling right over. Whilst on Windermere last weekend and battling against a good southerly gale, I was wondering if you could capsize a WB but with 21 years of ownership behind me I think I would prefer to be in a WB rather than anything else of a similar size.

[Old Forum]

Ben Fraser
Username: Ben_fraser

Registered: 10-2008
   
Posted on Sunday, October 26, 2008 - 08:52 pm:      
Yes, i'm told thats the technical term. But I think "the piont of no return" is much clearer! Many thanks David, thats very reassuring.

[Old Forum]

David_owens
Username: David_owens

Registered: 04-2010
   
Posted on Thursday, August 12, 2010 - 06:06 pm:      
I have just read an interesting article in a recent PBO magazine about a wood epoxy 17' cutter boat called a Shilling, whose hull looks very much like a Winklebrig, though it has a centreboard as opposed to bilge boards. Its ballast ratio is also pretty similar (145/600 as compared with the Winklebrigs 150/650). The above discussion shows how stable the Winklebrig is - though having sailed up the Cleddau with David in a real blow, I suspect the WB is a lot more stable with him at the helm than most - but can anyone add to the discussion what the point of no return actually is, and, if the boat does go over, whether the WB is self-righting - as the Shilling claims to be?

[Old Forum]

David_owens
Username: David_owens

Registered: 04-2010
   
Posted on Saturday, August 14, 2010 - 08:46 pm:      
As a postscript to the above I found a formula to calculate the point of vanishing stability in a boat in the following URL of the US Sailnet forums - 09-07-2998 (presumably 7th September in US money:

http://www.sailnet.com/forums/sailboat-design-construction/46840-limit-positive- stability.html

Using this formula, according to my calculations from published data, the pvs of a Winklebrig is 118 degrees, Admittedly, the formula is littered with caveats but it is the only attempt to quantify the pvs of a Winklebrig I've come across, and the Winklebrig does seem to compare rather better with inshore boats than I had expected. It is also consistent with the claims for the Shilling. On another topic - great new pics on the homepage slide show Julian!